. 9
( 21)


systematized and developed by the Arab physicians childbirth further during the 18th-c.
Ibn Sina (Avicenna) (980“1037) and Ibn Rushd Paris played an important role in the great trans-
(Averro«s) (1126“98), and the Jewish physician formation of medicine at the end of the 18th-c. The
Moses Maimonides (1135“1204). Galen™s works field of ˜clinical™ medicine was defined, based on the
were also adopted in the medieval Western Enlightenment desire to base all knowledge on
universities as the basis of the medical curriculum. sense-experience alone, following the work of the
The vernacular and anti-authoritarian medicine of Abb© de Condillac (1715“80). Here, in the course of
PARACELSUS, which was based on a mystical reading the French Revolution, the great public hospitals
of nature and disease and on chemical cures, proved were used in a systematic attempt to correlate signs
very popular in the 16th-c, and was developed later and symptoms during life with post-mortem dissec-
by HELMONT. But in general, Renaissance medicine tions, thus enabling the physician to know what
was concerned with attempts to recover the full internal changes were happening during disease.
Greek texts of Galen and Hippocrates, and the prac- Among the leaders of this development were Philippe
tices of these ancients were held up as models to Pinel (1745“1826) and Jean Nicholas Corvisart
copy. In this tradition, FRACASTORO analysed the new (1755“1821). Many new disease syndromes were

Heisenberg, Werner Karl

identified, and investigation of lesions was taken including the transmission of yellow fever by
to the level of tissue examination by BICHAT. mosquitoes, discovered by REED and his collabora-
This ˜clinical™ revolution was epitomized by the tors, and sleeping sickness by the tsetse fly,
invention of the stethoscope (˜chest-examiner™) by discovered jointly by Aldo Castellani (1877“1971),
LAENNEC, which has come to be the emblem of the
¨ BRUCE, and David Nabarro (1874“1958). RONALD ROSS
physician. received the second Nobel Prize for physiology or
During the 19th-c, nursing was transformed from medicine for identifying the life-cycle of the causative
a religious to a secular vocation, and it was especially agent of malaria. After the triumph of germ-theory, a
the exploits of Florence Nightingale (1820“1910) in number of earlier workers acquired posthumous
the Crimean War that raised public consciousness fame, being credited with having been early bacteri-
about the desirability of trained nurses for patient ologists, such as Fracastoro from the 16th-c and
care in hospital. Women became engaged in a SEMMELWEIS who, in the early 19th-c, urged the
parallel struggle to become doctors, and among the washing of the doctor™s hands to prevent the spread
pioneers were ELIZABETH BLACKWELL in the USA and of childbed fever in labour wards. Laboratory medi-
ELIZABETH GARRETT ANDERSON and SOPHIA JEX-BLAKE in cine came to dominate the public health movement
Britain. which, under the leadership of people such as Edwin
Laboratory medicine was built on techniques to Chadwick (1801“90) and John Simon (1816“1904) in
cultivate and control micro-organisms, and was Britain and Max von Pettenkofer (1818“1901) in
developed from the mid 19th-c, led by PASTEUR and Bavaria, had been seeking to improve the sanitary
KOCH, who worked in rivalry to develop techniques to conditions of the towns.
identify, culture, and control disease-causing bacteria During the 20th-c an increasing degree of special-
and other pathogenic micro-organisms. In the last ization in medical research and the advent of the
three decades of the century these two investigators high-tech hospital have meant less opportunity for
and their followers identified the causal agents of individuals to play a decisive role in medical advance.
many infectious diseases, such as malaria (Alphonse But the work of ALEXANDER FLEMING in discovering the
Laveran, 1845“1922), tuberculosis, cholera (both antibiotic properties of the penicillin mould, and the
Koch), and plague (Alexandre Yersin, 1863“1943, and efforts of FLOREY and CHAIN in developing it for
KITASATO). Pasteur™s school was particularly concerned medical use, was a further great turning point in
to develop preventive vaccines and Pasteur™s own modern medicine. All three shared the Nobel Prize in
vaccine against rabies in 1885 was an achievement of 1945. The more dramatic nature of laboratory medi-
great importance. Serums were developed that cine and surgery has tended to overshadow develop-
destroy the toxins produced by certain micro-organ- ments in clinical and social medicine, pharmacy, and
isms and produce immunity, and BEHRING received the epidemiology “ though all contribute to the high
first Nobel Prize for physiology or medicine in 1901 for state of medicine today. However, although life
developing serum therapy against diphtheria. EHRLICH expectancy has greatly increased in the last two
and MECHNIKOV later received Nobel Prizes for their centuries, it is a matter of debate quite how much
work on immunity and LISTER applied the insights of of this can be attributed to improvements in the
Pasteur to produce aseptic conditions that would scientific understanding of physiology and the
permit safe surgery. greater availability of medical care. Better nutrition,
Laboratory medicine was spurred on by the desire clean water, and effective sewers have probably been
of industrialized Western countries to develop just as important.
colonies and make them safe. Before the end of the
Andrew Cunningham, Wellcome Unit for the
century the causal agents and modes of transmission
History of Medicine, Cambridge
of many tropical diseases had been discovered,

burglars a few days after his death, but is known to earthquake to demonstrate that a sediment
have described a unified field theory combining ˜slump™, or turbidity current, travelling at up to
electromagnetism and gravitation. 85 km per hour had taken place. Such turbidity cur-
Heezen, Bruce Charles (1924“1977) US ocean- rents transporting large amounts of sediment
ographer: demonstrated existence of turbidity down the continental slope had previously been
currents. proposed as the cause of submarine canyons, but
Educated at Iowa State University and Columbia not observed. In 1957 Heezen and Ewing demon-
University, New York, Heezen worked at the strated the existence of a central rift in mid-ocean
Lamont“Doherty Geological Observatory at ridges.
Heisenberg, Werner Karl [hiyznberg] (1901“76)
Columbia from 1948 until his death. In 1952 he
used records of the times of the breakage of under- German physicist: developed quantum mechanics
water communications cables off the Grand Banks, and discovered the uncertainty principle.
Newfoundland, during the 1929 Grand Banks Heisenberg, son of a professor of Greek at the
Helmholtz, Hermann von

others, but is now generally accepted. Laplace™s
claim that the future of the universe could in prin-
ciple be deduced from the position and velocity of
all particles if given at one instant was rejected. For
example: to try to locate the accurate position of an
electron, radiation of short wavelength (such as
gamma rays) might be bounced off it. However,
such energetic rays will radically alter the elec-
tron™s momentum on collision, so that certainty in
its position is attempted at the expense of that in
momentum. In 1932, after Chadwick had discov-
ered the neutron, Heisenberg proposed that a
nucleus of protons and neutrons was a more satis-
factory model than one of protons and electrons, as
had been assumed. The components of the nucleus
should be held together by quantum mechanical
exchange forces, which was later confirmed by
Yukawa™s theory of the strong nuclear interaction
by which pi-mesons were exchanged. Later
Heisenberg put forward a unified field theory of
elementary particles (1966) which received little
general support.
Werner Heisenberg in 1926, one year after he developed
During the Nazi period, Heisenberg chose to
quantum mechanics. In 1927 he introduced the uncer-
tainty principle. remain and preserve the German scientific tradi-
tion, though he was not a Nazi supporter. He was
University of Munich, was educated at Munich and attacked by the Nazis for refusing to reject in any
Göttingen. He worked with Born in Göttingen, and way Einstein™s physics. As a consequence he lost
Bohr in Copenhagen. In 1927 he returned to a pro- the chance of the professorship at Munich in 1935
fessorship in Germany at Leipzig. as Sommerfeld™s successor. During the war
Heisenberg was a major creative figure among Heisenberg was called to lead the atomic energy
those who revolutionized physics by quantum and weapons programme, becoming director of the
mechanics. At 24 he formulated a non-relativistic Kaiser Wilhelm Institute in Berlin in 1941. After the
form of the theory of quantum mechanics, produc- war he helped establish the Max Planck Institute at
ing the matrix mechanics version, and received the Göttingen and moved with it to Munich in 1955 as
1932 Nobel Prize for physics for this work. An equiv- its director.
alent theory called wave mechanics was produced Heisenberg™s wartime role is controversial. He
independently by Schrödinger in 1925 and they claimed to have had no intention of allowing an
were shown to be equivalent by von Neumann. atomic bomb to reach Hitler™s hands, and stated
Heisenberg broke away from the visual concept of that in such a key role he could have diverted the
the atom and avoided problems such as the appar- programme if it ever neared success. He claimed to
ent wave-particle duality by considering only have revealed this to Bohr in 1941, but Bohr said
observable quantities of the atom as ˜real™. He sepa- that he failed to understand Heisenberg™s guarded
rated in the theory the system of interest and oper- comments. The weapon was not produced by
ations on that system to produce an observable Germany probably because of a higher priority for
quantity. Respectively these were expressed as a planes and flying bombs.
Helmholtz, Hermann (Ludwig Ferdinand) von
matrix and a mathematical operation on the
matrix to give a value. He used the theory to predict (1821“94) German physicist and physiologist: a dis-
successfully the observed frequencies and intensi- coverer of the law of conservation of energy;
ties of atomic and molecular spectral lines. He con- achieved major results in theories of electricity and
cluded that two forms of molecular hydrogen, magnetism, and on the physiology of vision and
called ortho- and para-hydrogen, exist with their hearing.
nuclear spins aligned in the former and opposed in Helmholtz must be the most versatile scientist of
the latter. his century: he did first-class work in physics and
In 1927 Heisenberg discovered a further aspect of physiology, both theoretical and experimental, and
quantum mechanics, the principle of uncertainty; he was no mean mathematician. He has been
that it is impossible to determine exactly both the claimed to be the last scholar whose work ranged
position and momentum of a particle simultane- over the sciences, philosophy and the arts. He
ously. The uncertainty in position ∆x and in believed that his diversity of interests was helpful
momentum ∆p obey ∆x∆p ≥ h/4π where h is the to him in giving novel viewpoints in his researches.
Planck constant. This relation removed absolute As a child he was ˜delicate™ and often ill, but his
determinacy, or cause and effect, from physics for parents did their best to amuse him. At school he
the first time and replaced it with a statistical prob- found he did badly at memory work and rote-learn-
ability. This deeply troubled Einstein and some ing, but he enjoyed the logic of geometry and was
Henry, Joseph

delighted by physics. However, his father knew of
no way of studying physics except as a medical stu-
dent, for which he could get a university grant, pro-
vided he followed it by some service as an army
surgeon. He must have done well as a medical stu-
dent at Berlin, because after a short time as an army
surgeon he became professor of physiology at
Königsberg and later at Bonn and Heidelberg, and
of physics at Berlin.
He was 26 and working in medicine when he pub-
lished his pamphlet On the Conservation of Force in
1847; his ideas in it on the law of conservation of
energy were much more precise than the ideas on
the law given by J R Mayer (1814“78), and more
wide-ranging than those of Joule; Helmholtz gave
examples of the law in mechanics, heat, electricity
and chemistry, with numerical values.
By 1850 he had moved to physiological optics and
colour vision. An early success for him in this area
was his invention of the ophthalmoscope for view-
ing the human retina. (Babbage had invented a sim- J B van Helmont
ilar device 3 years earlier, but his medical friends
failed to use it.) Helmholtz was more successful,
and his device not only revolutionized the study of 5 years, when its weight increased from 5 to 169 lb
diseases of the eye but also was of value to physi- (2.27 to 76.66 kg); the earth it had grown in had
cians generally in giving the only direct view of the hardly lost weight, and he had given the tree only
circulatory system. His study of the sense organs rainwater. So in his view the tree (and presumably
was continued in work on the ear and the mecha- all vegetation) was made of water. He was half-cor-
nism of hearing, where he argued that the cochlea rect (willow is about 50% water); and he failed to
resonates for different frequencies and analyses realize that the plant had taken in CO2 from the air.
complex sounds; and he developed a theory on the He studied gases (he was the first to use the word
nature of harmony and musical sound (he was a ˜gas™, based on the Greek chaos) but he had no
skilful musician). method of collecting them; and better distinctions
Earlier he had worked on the speed of nerve between different gases had to wait for Priestley™s
impulses and showed that this was of the order of a work. He had rather confused ideas on animal
tenth of the speed of sound. He was a masterly digestion but, in directing thought to animal
experimenter, but in later life he gave up physiol- chemistry, his views were valuable.
Henderson, Thomas (1798“1844) British astrono-
ogy for physics and became more interested in
theoretical work, including Maxwell™s on electro- mer: first measured stellar parallax.
magnetic radiation. He encouraged his pupil and Henderson was a legal clerk and amateur
friend Hertz to work in this area, with important astronomer who became director of the Cape of
results: Hertz discovered radio waves in 1888. Other Good Hope Observatory in 1831. He was one of the
first to detect and measure the parallax of a star, ±
pupils included Boltzmann and Michelson; he
had a great many pupils, his fame as a physicist Centauri, in 1832 (± Centauri is actually three stars
compared with that of his friend Kelvin in and, at 4 light years distance, is still the closest star
England, and in Germany he was said to be ˜the system to us). Unfortunately, his hesitation in pub-
most illustrious man next to Bismarck and the old lishing his discovery before he had thoroughly
Emperor™. checked his result meant that Bessel, who in 1838
Helmont, Jan Baptista van (c.1579“1644) Flemish made similar measurements on 61 Cygni, received
alchemist, chemist and physiologist: made early most of the credit for the first determination of a
studies of conservation of matter. stellar distance.
Henry, Joseph (1797“1878) US physicist: pioneer of
A member of a noble and wealthy family,
Helmont studied the classics, theology and medi- electromagnetism.
cine before turning ˜for 7 years to chemistry and Strangely, no American after Franklin did much
the relief of the poor™. He believed in alchemy, but for the study of electricity for 75 years, when Henry
his own work represents a transition to chemistry did a great deal. In many ways Henry is the tradi-
proper. He used a chemical balance and understood tional American of folklore; tall, handsome and
clearly the law of indestructibility of matter (eg healthy, he was still a strenuous researcher at 80.
that metals, dissolved in acid, can be recovered). He Growing up in Albany in New York State with a wid-
knew a fair range of inorganic salts and the acids owed mother, he was not fond of schoolwork and at
H2SO4 and HNO3. He believed that all matter was 15 was apprenticed to a watchmaker, but the busi-
based on two elements or principles, air and water. ness soon failed. For a year he wrote plays and acted
In an experiment on this, he grew a willow tree for in them, and then by chance read a book on science
Henry, William

which reshaped his life. He attended the Albany The law holds well only for slightly soluble gases at
Academy, did well and spent a period as a road engi- low pressures.
neer before taking a job as teacher of mathematics Henry was a close friend of Dalton but, despite
at the Academy, researching on electricity in his superior skill and range as an experimenter, lacked
spare time. His research gave him enough reputa- his friend™s boldness as a theorist and never com-
tion to secure a post at the College of New Jersey mitted himself to the atomic theory whose birth he
(which became Princeton) in 1832, teaching a full had assisted.
Hermite, Charles [airmeet] (1822“1901) French
range of sciences.
In 1825 Sturgeon devised an electromagnet with mathematician: developed theory of hyperelliptic
a varnished soft iron core wrapped by separate functions and solved the general quintic equation.
strands of uninsulated wire. Henry in 1829 much Hermite had an inability to pass examinations, and
improved this by using many turns of thin, insu- congenital lameness, but he greatly influenced his
lated, wire. (He supervised the making of one at generation of mathematicians. Having entered and
Yale in 1831 that would lift a tonne.) Also in 1831 he then been dismissed from the École Polytechnique,
made the first reciprocating electric motor, as ˜a Hermite finally, but only just, graduated at 25; by
philosophic toy™. Like his magnets it was powered then he was clearly an innovative mathematician.
by batteries, his only source of current. He had wire He gained a teaching post at the Collège de France,
in plenty, from an unknown source, and used miles was elected to the Paris Acad©mie des Sciences
of it. In 1830 he discovered electromagnetic induc- (1856) and immediately caught smallpox. Reco-
tion, ˜the conversion of magnetism into electricity™. vering, he eventually received a professorship at the
Faraday also discovered it independently soon École Normale (1869) and the Sorbonne (1870).
after, and published first. However, Henry, in 1832, Hermite™s creative work included extending
was the first to discover and to publish on self- Abel™s theorem on elliptic functions to hyperellip-
induction, and the unit is named after him. A coil tic functions and using elliptic functions to give a
has a self-inductance of 1 henry (H) if the back emf solution of the general equation of the fifth degree,
in it is 1 volt when the current through it is chang- the quintic (1878). He proved that the number e is
ing at 1 ampere per second. In 1835 he introduced transcendental (that is, not a solution of any alge-
the relay, which made long-distance electric braic equation with rational coefficients) and used
telegraphy practical, an important step in North the techniques of analysis in number theory. He set
America. out the theory of Hermite polynomials (1873),
When he was 49, Henry became first director of which are polynomial functions now much used in
the Smithsonian Institution. This had a curious quantum mechanics, and of Hermitian forms,
history. James Smithson was an unrecognized which are a complex generalization of quadratic
bastard son of the Duke of Northumberland. forms.
Hero (of Alexandria) (lived c.ad 62) Greek physi-
Resentful of his position, he was determined that
˜my name shall live in the memory of man when cist: invented a steam-powered engine.
the Northumberlands ¦ are extinct and forgotten™ Apart from writings ascribed to him, nothing is
and he therefore left a large fortune to go to the known of Hero. Some have argued that he had little
USA (with which he had no links of any kind) to scientific knowledge and was simply a recorder of
found ˜an Establishment for the increase and diffu- ingenious devices, but recent study shows that he
sion of knowledge™. Henry shaped it well; it became grasped all the mathematics of his time. His books
˜the incubator of American science™ and he was the Pneumatics and Mechanics make it clear that he was a
model administrator. A strict Calvinist, he resisted teacher of physics, and these and other books
patents or wealth for himself and refused for 32 survey the knowledge and devices known in his
years to increase his salary of $3500. day, including pumps, siphons, a coin-operated
Henry, William (1774“1836) British chemist: discov- machine and surveying instruments. He devised
ered law of gas solubility. Hero™s engine, a primitive reaction turbine in
Henry was the third and most successful son of which steam emitted by two nozzles facing in oppo-
Thomas Henry, whose profitable ventures in chem- site directions caused rotation.
Herschel, Caroline (Lucretia) [hershl] (1750“
istry had included the early use of chlorine for
bleaching textiles, the preparation and use of 1848) German“British astronomical observer; dis-
bleaching powder (Cl2 absorbed in lime) as a useful covered eight new comets.
alternative to the gas, and the making of ˜calcined Caroline Herschel™s introduction to astronomy
magnesia™ (ie Mg(OH)2) for medicinal use. Young was entirely due to her devoted affection for her
William was injured by a falling beam at the age of elder brother William Herschel but she became
10; the injuries gave him ill health and pain the most famous woman astronomer of her time. In
throughout his life, and he finally killed himself. 1835 she was one of the first two women elected to
He qualified in medicine in 1807 but his research honorary fellowship of the Royal Astronomical
was mainly in chemistry. He is now best known for Society.
Henry™s Law, which states that the mass of a gas dis- Caroline, born in Hanover, was brought up to be
solved by a given volume of a solvent, at a constant the household servant, with minimal education;
temperature, is directly proportional to the pres- her mother believed that it was her daughter™s duty
sure of gas with which the solvent is in equilibrium. to look after her brothers. Her father included
Herschel, Sir John

John Herschel™s work and for his use she compiled
a new catalogue of nebulae arranged in zones, from
William™s work, but it was not published. In 1828
she was awarded the Gold Medal of the Royal
Astronomical Society and in 1846 the Gold Medal
for Science by the King of Prussia. She held a record
for comet discoveries by a woman until 1987 when
it was broken by Carolyn Shoemaker.
Caroline Herschel™s contributions to astronomy
were made for the love of her brother, but she
brought perseverance, a sharp eye and notable
accuracy to the work.
Herschel, Sir John (Frederick William) [hershl]
(1792“1871) British astronomer and physicist: sur-
veyor of the southern sky.
Although his father William Herschel, the
˜gauger of the heavens™, did notable scientific work,
John did more and ranged outside his father™s
astronomical interests. For an only child his
famous father was rather overwhelming, but his
close friendship with his aunt Caroline Herschel
ended only with her death at 98.
He graduated from Cambridge in mathematics in
Caroline Herschel: the only portrait of her as a young
woman, by an unknown artist. 1813 with the highest distinction, then began to
study law, but physics attracted him. His home
Caroline in the musical instruction he gave his sons experiments with polarized light gave some valu-
but warned her ˜against all thoughts of marrying, able results; he also deduced that polarized light
saying I was neither hansom (sic) nor rich, it was not should be rotated by an electric field, as was later
likely that anyone would make me an offer™. After confirmed experimentally by Faraday. For a time,
her father™s death Caroline continued to practise following two failed love affairs, he was uncertain
her singing and longed for independence. William of what career to follow. From 1816 he assisted his
Herschel proposed to his mother and elder brother father in the study of double stars and nebulae, and
that she should join him in Bath and take singing thereafter he fixed on a scientific career, which was
lessons, but this was only agreed to in 1772 after he surprisingly wide-ranging. Astronomy continued
had paid for a servant to replace Caroline. to attract him and in the 1830s he decided to
Caroline™s brief career as an oratorio singer faded extend their survey of the sky to the southern
as she became indispensable to William in his hemisphere. He arrived at the Cape in 1834, accom-
increasing interest in astronomy. Lessons in math- panied by his young wife, two large telescopes, a
ematics and astronomy were given at the breakfast mechanic and a children™s nurse, and in 4 years of
table and Caroline became a valuable assistant. She energetic work he mapped most of the southern
was involved in every aspect of his work: in pound- sky.
ing and sieving horse manure to make material for He worked in meteorology and geophysics and
moulds and in the grinding and polishing of the planned Sir J Ross™s geomagnetic survey of the
metal mirrors for telescopes. They observed as a Antarctic. He was an expert chemist, and major
team: she assisted in the recording, prepared cata- contributions to early work on photography are
logues and assisted in writing papers for publication. due to him: he devised the cyanotype process. This
In 1783 she began to ˜sweep for comets™ with a used paper impregnated with an iron compound
small refracting telescope and discovered three (ammonium ferricitrate), which on exposure to
new nebulae. Her opportunities for independent light formed Prussian blue. The process was simple
observation occurred only when William was away and cheap and gave a permanent print, but the
and not needing her assistance. However, between response to light was too slow for camera exposures
1786 and 1797 she discovered eight comets and and prints were made by placing the subject in con-
gained a reputation as an astronomer in her own tact with the sensitized paper and exposing to
right. As a result of her increasing fame, she was strong light (the process became much used in the
awarded £50 a year by George III in recognition of 20th-c to make the ˜blueprint™ copies of engineer™s
her work as William™s assistant, the first official drawings and was also used at Mafeking during the
female assistant to the Court Astronomer. William Boer War, when Baden-Powell directed that bank-
found Flamsteed™s star catalogue very difficult to notes and postage stamps be reproduced during
use; Caroline™s revision of this, Index to Flamsteed™s the siege).
Observations of the Fixed Stars, was published by the For conventional silver-based photography he
Royal Society in 1798. introduced ˜hypo™ as a fixing agent and was a pio-
On William™s death in 1822 Caroline returned to neer in astronomical photography. In 1839 he made
Hanover. She took a keen interest in her nephew the first photograph on a glass plate (previously
Herschel, Sir William

sensitized paper had been used), prepared the first
coloured photographs of the Sun™s spectrum and
introduced the words ˜negative™ and ˜positive™ into
˜photography™ (also his word), and the word ˜snap-
shot™. In 1850 he became Master of the Mint, a move
which he was persuaded to make only by forceful
appeals to his patriotism; he did the job well but
without enjoyment for 5 years. At his death he was
˜mourned by the whole nation, as a great scientist
and one of the last of the universalists™.
Herschel, Sir (Frederick) William [hershl] (1738“
1822) German“British astronomer: discovered
Uranus, the Sun™s intrinsic motion through space
and the true nature of the Milky Way.
Herschel followed his father in becoming a musi-
cian in the Hanoverian Guards, entering as an
oboist at 14. At 19 he came to England, working as a
freelance musician before appointment as an
organist in Bath. He was a keen amateur telescope
maker and observer. His sister Caroline Herschel
joined him in Bath in 1772.
Herschel™s first important discovery was the Sir William Herschel, aged 46: engraving based on a por-
planet Uranus in 1781. This achievement, helped by trait by L T Abbott.
his desire to name it after George III, resulted in
his appointment the following year as Court showing them to converge towards a point. He had
Astronomer. This enabled him to finance the con- a special interest in double stars, cataloguing 800 of
struction of a reflecting telescope 20 feet in length them and discovering in 1793 that many were in
and with an aperture of 20 inches, with which he relative orbital motion. In 1820 he published a cat-
was to make many further discoveries. In 1787 he alogue of over 5000 nebulae (a task that his son,
found two satellites of Uranus, Titania and Oberon, John, was to continue in the southern hemisphere).
and soon afterwards two of Saturn, Mimas and He was the first to recognize the true nature of the
Enceladus. In 1783 he discovered the intrinsic Milky Way as a galaxy by counting the number of
motion of the Sun through space by careful analy- stars visible in different directions, finding that the
sis of the proper motions of seven bright stars, greatest number lie in the galactic plane, and the

William Herschel in his garden at Datchet with the 20-foot (focus) reflecting telescope made by him and his sister
Caroline. He thought it the most satisfactory of all their telescopes, using it to record over 2000 nebulae, star clusters
and comets. It was awkward to handle, and Caroline (who positioned it and recorded observations) noted ˜I could give
a pretty long list of accidents, which were near proving fatal to my brother as well as myself.™
Herzberg, Gerhard

least toward the celestial poles. Investigating the Influenced by Helmholtz and by Maxwell™s elec-
effect of parts of the Sun™s spectrum on a ther- tromagnetic theory, he was the first to demon-
mometer, he discovered infrared radiation, outside strate the existence of radio waves, generated by an
the visible range. electric spark. In 1888 he showed that electromag-
Hershey, Alfred (Day) (1908“97) US biologist: netic waves were emitted by the spark and could be
demonstrated information-carrying capability of detected by a tuned electric circuit up to 20 m
bacteriophage DNA. away. Further experiments demonstrated that the
A graduate of Michigan State College, Hershey waves, which had a wavelength of about a foot,
taught at Washington University, St Louis, until could be reflected (from the laboratory walls),
1950 and then worked at the Carnegie Institution of refracted (through a huge prism of pitch), polarized
Washington. His best-known work was done in the (by a wire mesh) and diffracted (by a screen with a
early 1950s with Martha Chase (1927“ ), when they hole in it) in the same way as light, and travelled at
proved that DNA is the genetic material of bacterio- the same speed. This was an important verification
phage (the virus that infects bacteria). They used of Maxwell™s ideas. Hertz also discovered in 1887
phage in which the DNA core had been labelled with that an electric spark occurs more readily when the
radioactive phosphorus and the protein coat of the electrodes are irradiated with ultraviolet light (the
phage with radioactive sulphur. The work showed Hertz effect), a consequence of the photoelectric
that when phage attacks a bacterial cell it injects effect. Hertz died at 36 (from blood poisoning) and
the DNA into it, leaving the protein coat on the out- did not live long enough to see Marconi turn radio
side; but the injected DNA causes production of new transmission into a means of worldwide communi-
phage, complete with protein. The DNA must carry cation. The SI unit of frequency, the hertz (Hz, one
the information leading to the formation of the cycle per second), is named in his honour.
Hertzsprung, Ejnar [hertsprung] (1873“1967)
entire phage particle. Avery had been cautious on
the status of DNA as an information-carrier; Danish astronomer: discovered stellar spectral
Hershey proved it. Hershey was a phage expert type/luminosity relationship.
already, having shown that spontaneous mutations Trained as a chemical engineer, Hertzsprung did
occurred in it in 1945. research in photochemistry before appointment as
Delbrück™s early impression of Hershey was that an astronomer at the Potsdam Observatory in 1909.
he preferred whisky to tea, liked living on his boat His work on photography led to his success in clas-
for months at a time and was very independent. sifying stars. Hertzsprung was the first to realize
Delbrück, S E Luria (1912“91) and Hershey were the that there was a relationship between the spectral
nucleus of the ˜phage group™ who contributed so colour of stars (as defined and classified by Antonia
much to molecular biology. The trio shared a Nobel Maury) and their luminosity; for most stars the
Prize in 1969. more blue the colour, the brighter the star. He also
Hertz, Heinrich Rudolph (1857“94) German physi- found that a small proportion of stars did not fit
cist: discovered radio waves. this pattern, being far brighter than might be
Hertz studied at the universities of Munich and expected for their colour. These two groups are
Berlin, at the latter under Helmholtz, whom he now called main sequence stars (the numerous
served as an assistant. In 1885 he was appointed pro- faint dwarfs) and red giants (fewer, more luminous)
fessor of physics at Karlsruhe Technical College and respectively. His results were published in 1905 and
later held a professorship at the University of Bonn. 1907 in obscure journals. Independently, in 1913,
Russell came to the same conclusions, the usual
representation of their results being known as the
Hertzsprung“Russell diagram (see p. 311). This
discovery had a great effect on ideas about stellar
His second important achievement was to utilize
the period“luminosity relationship of Cepheid
variable stars, discovered by Henrietta Leavitt in
1912, as a means of calculating stellar distances. In
1913 Hertzsprung was able to determine the dis-
tance of some nearby Cepheids from their proper
motion (the only method available for measuring
stellar distance up to that time), and using Leavitt™s
results he began to calibrate the Cepheid variable
technique. These first measurements of distances
outside our Galaxy were developed by Shapley.
Hertzsprung was an active researcher until he was
over 90.
Herzberg, Gerhard [hertsberg] (1904“99) German“
Canadian physical chemist: devised methods of
analysing electronic spectra to detect new mole-
cules and to find molecular dimensions.
Heinrich Hertz
Hess, Germain Henri

Born and educated in Germany, Herzberg taught initial states of the system and is independent of all
at Darmstadt from 1930 until 1935 when he emi- intermediate states. The law enables the heat of
grated to Canada. For 20 years until 1969 he was reaction to be calculated in a case where direct
head of the physics division for the National measurement is impractical. Hess™s Law follows
Research Council in Ottawa, which he made into a from the law of conservation of energy, but the
centre of international renown in spectroscopy. He latter was not clearly understood in 1840.
developed and used spectroscopic methods for a Hess researched in other areas, and did much for
variety of purposes, including the measurement of the development of chemistry in Russia, where he
energy levels in simple atoms and molecules for taught in St Petersburg.
Hess, Harry Hammond (1906“69) US geologist and
use in testing theories of their structure and for the
detection of unusual molecules and radicals, some geophysicist: proposed sea-floor spreading hypoth-
of which could be detected by flash photolysis in esis.
the laboratory and others by astrophysical methods Hess spent most of his academic life at Princeton
(for example CH and CH+ in interstellar space and University, moving there in 1934. During the
the flexible C3 in comets). For his work on the elec- Second World War he distinguished himself in the
tronic structure and geometry of molecules, partic- US Navy by conducting echo-sounding work in the
ularly free radicals, he was awarded the Nobel Prize Pacific, during which he discovered a large number
for chemistry in 1971. of strikingly flat-topped seamounts, which he inter-
Hess, Germain Henri (1802“50) Swiss“Russian preted as sunken islands, naming them guyots
chemist; pioneer of thermochemistry. (after Arnold Guyot (1807“84), an earlier Princeton
When Hess was 3 years old his father, a Swiss geologist).
artist, became tutor to a rich Moscow family and Following the war there was a great increase in
the boy moved from his birthplace (Geneva) to knowledge about the sea bed, and it became appar-
Russia. He was there for the rest of his life, taking a ent that parts of the ocean floor were anomalously
medical degree at Tartu in 1825 and then visiting young. In 1962, following the discovery of the
Berzelius in Stockholm. The visit was only for a global extent of the mid-ocean ridges and their cen-
month, but its influence was permanent. From tral rift valleys by Ewing, Hess proposed his sea-
1830 he studied the heat evolved in chemical reac- floor spreading hypothesis to account for these
tions, as a route to the understanding of ˜chemical facts. He suggested that material was continuously
affinity™. Rather little had been done in thermo- rising from the Earth™s mantle to create the mid-
chemistry since the work by Lavoisier and Laplace. ocean ridges, which then spread out horizontally to
Hess™s Law (the law of constant heat summation) of form new oceanic crust; the further from the mid-
1840 states that the heat change accompanying a ocean ridge, therefore, the older the crust would
chemical reaction depends only on the final and be. He envisaged that this process would continue

Four Nobel laureates in physics: V F Hess, W K Heisenberg, C D Anderson and A H Compton (with moustache) holding
his cosmic ray detector.
Hevesy, György

as far as the continental margin, where the oceanic ophthalmologist, but gave up this career to work in
crust would sink beneath the lighter continental physiology and from 1917“51 headed physiology in
crust into a subduction zone, the whole process the university of Zürich. The precision surgery he
thus forming a kind of giant conveyor belt (see dia- had learned as an ophthalmologist was to prove
gram below). Palaeomagnetic and oceanographic useful; in the 1920s he began his study of the auto-
work, notably by Matthews and Vine, confirmed nomic nervous system, which controls involuntary
the hypothesis. Later, as chairman of the Space functions such as breathing, blood pressure, tem-
Science Board of the National Academy of Sciences, perature and digestion.
Hess also had an influential effect on the American It was already known roughly which parts of the
space programme. brain are involved in this control; but Hess made
Hess, Victor Francis (1883“1964) Austrian“US this knowledge much more precise. He used cats
physicist: discovered cosmic rays. into which, under anaesthetic, a fine insulated
Son of a forester, Hess was educated at Graz, wire with a bare end was inserted so that the end
receiving his doctorate in 1906. He worked on was located at a defined point in the midbrain.
radioactivity at Vienna until 1920, and afterwards When the animal was again conscious, a very small
at Graz, New Jersey and Innsbruck. In 1931 he set up current was passed into the wire. Hess found that
a cosmic ray observatory on the Hafelekar moun- by this stimulation of small groups of cells in the
tain. When the Nazis occupied Austria in 1938 Hess midbrain he could induce a variety of reactions,
was dismissed, as his wife was Jewish, and he including sleep, rage, evacuation and changes in
became professor of physics at Fordham University, blood pressure and respiration. Similarly, in the
New York City. hypothalamus he located centres that appeared
In 1910 T Wulf measured the background to control other parts of the sympathetic and
radioactivity of the atmosphere at the top of the parasympathetic components of the autonomic
300 m Eiffel Tower with a simple electroscope and system. This influential work led to detailed map-
showed that it was greater than at ground level, ping of the brain and began to relate physiology to
indicating that it came from an extraterrestrial psychiatry. He shared a Nobel Prize in 1949.
Hevesy, György [heveshee] (1885“1966) Hunga-
source; but the results were not conclusive. A
Gockel in 1912 also used the rate of discharge of a rian“Swedish radiochemist: introduced use of
gold-leaf electroscope to measure the radioactive radioactive ˜tracers™ in analysis.
ionization of the air, this time from a balloon; Hevesy was a highly mobile chemist; he worked
again the results were inconclusive. However in in at least nine research centres in seven countries.
1911“12 Hess made 10 balloon flights and showed His visit to work with Rutherford in Manchester
that the ionization is four times greater at 5000 m (1911“13) established his interest in radiochem-
than at ground level. Night ascents and an ascent istry. While there he found that ordinary lead and
during an eclipse of the Sun in 1912 showed that radioactive ˜radium-D™ are chemically inseparable;
the radiation could not be from the Sun. Millikan later it was realized that radium-D is an isotope of
in 1925 named these high-energy particles ˜cosmic lead, with relative atomic mass 210, that happens
rays™. Their study led to C D Anderson™s discoveries to be radioactive. Consequently, very small amounts
of the positron and muon and Powell™s discovery of lead can be ˜traced™ by mixing into the lead some
of the pi-meson. Hess shared the 1936 Nobel Prize radium-D and then taking advantage of the fact
for physics with Anderson. that minute levels of radioactive material are easily
Hess, Walter Rudolf (1881“1973) Swiss neurophys- located by using a counter, or by photography. In
iologist: showed that localized areas in the brain this way Hevesy and F A Paneth (1887“1958), in
control specific functions. 1913, were able to find the solubility in water of
Hess studied medicine at five universities in lead sulphide and lead chromate; both are insuffi-
Switzerland and Germany and became a specialist ciently soluble for traditional methods to measure
their solubility accurately. In 1934 he used a stable
but trackable isotope (deuterium) in heavy water,
sea level
D2O, to measure the water exchange between gold-
ocean ocean
fish and their surroundings. In 1934 also he used
radiophosphorus to locate phosphate absorption in
continental crust
human tissue. The technique has since been much
Moho oceanic
used and suitable ˜marker™ isotopes for use as trac-
Moho base of plate
ers are now widely available. In 1935 he devised a
base of variant of this, activation analysis.
plate In 1922 Bohr predicted the existence of a new ele-
ment and suggested that Hevesy should look for it
asthenosphere asthenosphere in zirconium ore. Working with D Coster (1889“
(upper mantle) 1950), who had experience of Moseley™s X-ray
method, Hevesy found the new element (atomic
number 72) and it was named hafnium (Hf). He
was awarded a Nobel Prize in 1943 for his work on
Subduction zone
Hewish, Antony

Later, in 1945, Hey used radar to track the paths
of V2 rockets approaching London at about 100
miles high. A problem here arose from spasmodic
transient radar echoes at heights of about 60 miles,
arriving at a rate of five to 10 per hour. When the V2
attacks ceased, the echoes did not; Hey concluded
that meteor trails were responsible and that radar
could be used to track meteor streams, and could of
course do so by day as well as by night.
He went on to locate in 1946 a radio source iden-
tifiable with Cygnus A, a powerful discrete stellar
radio source. Jansky, in 1933, had shown that a
radio source exists in our Galaxy (the Milky Way)
and Reber, using his homemade equipment, had
made the first contour maps of cosmic radio noise
Antony Hewish (standing, left) with (Sir) Martin Ryle.
distribution in 1944 and had shown that the Sun
was a radio emitter, unaware of Hey™s results of
Hewish, Antony (1924“ ) British radio astrono- 1942, which could not be published until after the
mer: identified first pulsar. war. Jansky and Reber moved on to other work after
Hewish studied physics at Cambridge and worked their initial discoveries and Hey became Head of
with Ryle on radio telescopes. He became particu- the AORG in 1949. From 1950 radio astronomy
larly interested in the scintillation of quasars, the expanded enormously, in the hands of Lovell,
radio equivalent of twinkling stars, and used this Hewish, Ryle and others.
Heyrovsky, Jaroslav [hiyrofskee] (1890“1967)
to examine the solar wind and clouds in inter-
planetary space. Czech physical chemist: inventor of polarography.
In 1967 he completed a radio telescope of Heyrovsky studied physical science at Prague and
unusual design for further work on scintillation. in 1910 came to London as a research student in
Together with his student Jocelyn Bell (Burnell), physical chemistry. It was then that he began work
he discovered remarkably regular pulsed signals on polarography, but this was interrupted by the
coming from a tiny star within our Galaxy; they First World War and the method was perfected by
had found the first pulsar. Many other pulsars have him in Prague in the 1920s. It is an electrochemical
since been found and are believed to be rapidly method of analysis, applicable to ions or molecules
rotating neutron stars, typically only 10 miles in that can be electrolytically oxidized or reduced in
diameter, which emit beamed radiation like a solution using mercury electrodes. By plotting the
lighthouse. Hewish was awarded the Nobel Prize voltage versus current curve (a polarogram) as the
for physics for this discovery in 1974. voltage between the electrodes is increased, differ-
Hey, James Stanley (1909“2000) British physicist: ent species are revealed as steps in the curve.
pioneer radio astronomer. The method is able to analyse several substances in
Hey studied physics at Manchester, graduating in one solution and is capable of high sensitivity.
1930, and obtained his master™s degree in X-ray Heyrovsky won a Nobel Prize in 1959.
Higgs, Peter (Ware) (1929“ ) British cosmologist
crystallography the next year. He was then a
teacher of physics in a northern grammar school and particle physicist: devised the ˜Higgs field™
for some years. The Second World War began in theory.
1939, and in 1942 Hey joined the Army Operational Educated at Bristol, London and Edinburgh,
Research Group (AORG) after a 6-week course at the Higgs taught and researched in Edinburgh from
Army Radio School. His task was to work on radar 1960 and became professor of theoretical physics
anti-jamming methods; for a year German jam- there in 1980.
ming of Allied radar had been a problem and the The concept of mass is complex. In classical
escape of two German warships (Scharnhorst and physics, the mass of a body is a measure of its iner-
Gneisenau) through the English Channel, aided by tia, its reluctance to undergo a change of velocity.
enemy radar jamming from the French Coast, had In this sense, mass can be defined operationally as
highlighted the problem. In February 1942 Hey had the ratio of the magnitudes of the force F and the
reports of severe noise jamming of anti-aircraft acceleration a it produces in a body of mass m; so
radars in the 4“8 m range. Realizing that the direc- m = F/a. This definition, due to Euler, was later used
tion of maximum interference seemed to follow by Newton, who recognized also that this ˜inertial™
the Sun, he checked with the Royal Observatory mass is apparently universally proportional both to
and found that a very active sunspot was traversing the active gravitational mass of the body (the mea-
the solar disc. He concluded that a sunspot region, sure of the gravitational field it produces) and to its
which was believed to emit streams of energetic passive gravitational mass (the measure of the grav-
ions and electrons in magnetic fields of around 100 itational pull exerted on it by other bodies).
G (gauss), could emit metre-wave radiation. In 1942, Einstein™s work embraced mass in his theory of rel-
G C Southworth in the USA also linked the Sun with ativity, which assumed the identity of inertial and
radio noise, this time in the centimetre-wave region. gravitational mass and also showed that a mass m is

related to the energy E involved in its destruction or sum of squares of co-ordinates a convergent series.
generation by E = mc2. This is now called Hilbert space, and is much used
The elementary particles from which matter is in pure mathematics and in classical and quantum
made have masses over a large range, from the light field theory. His ideas on operators in Hilbert
electron to the heavier W and Z particles and the space prepared the way for Weyl, Schrödinger,
top quark. It is not obvious why particles, and there- Heisenberg and Dirac.
fore matter, should possess mass at all. In this con- Hilbert™s work also gave rise to the ˜Hilbert pro-
text, a theory due to Higgs provides a possible gramme™ of building mathematics axiomatically
explanation. The theory proposes that all space is and using algebraic models rather than intuition.
permeated by a field (the Higgs field) which has While a productive controversy arose, greatly influ-
some similarity to an electromagnetic field. A par- encing mathematical philosophy and logic, this
ticle moving through this field, and interacting formalistic approach was later displaced by
with it, will appear to have mass; and the greater Gödel™s work. Hilbert™s views on proof theory were
the interaction the larger the mass. later developed by G Gentzen. In 1900 Hilbert pro-
In general a field has a particle associated with it; posed 23 unsolved problems to the International
the electromagnetic field is associated with the Congress of Mathematicians in Paris. The mathe-
photon (which has no mass). Analogously, the matics created in the solution of many of these
Higgs field may be linked with a particle (the Higgs problems has shown Hilbert™s profound insight
boson, believed to be heavy) or possibly with more into the subject.
Hinshelwood, Sir Cyril (Norman) (1897“1967)
than one particle. Proof or disproof of the existence
of such a particle and other aspects of the theory British physical chemist: applied kinetic studies to
would be of the highest value in theoretical a variety of problems.
physics. It would illuminate the nature of mass and Hinshelwood™s career, except for war service
gravitational attraction and perhaps link the latter from 1916 working on explosives in an ordnance
with the other known physical forces (electromag- factory, was spent almost entirely in Oxford. His
netic force, and the strong and weak nuclear early research, developed from his war work, was
forces). on the explosion of solids, but he soon turned his
Hilbert, David (1862“1943) German mathema- interest to explosive gas reactions. In the 1920s he
tician: originated the concept of Hilbert space. made a close study of the reaction of hydrogen with
Hilbert was educated at the universities of oxygen, which was a model for such research and
Königsberg and Heidelberg, spending short periods led to a shared Nobel Prize in 1956. He also studied
also in Paris and Leipzig. After 6 years as a the rates and catalytic effects in other gas reactions
Privatdozent (unsalaried lecturer) at Königsberg he and reactions in the liquid phase. His later work
became a professor there in 1892. In 1895 he was applied the ideas of chemical kinetics to the growth
given the prestigious chair in mathematics at of bacterial cells. In 1950 he made the suggestion,
Göttingen, which he retained until 1930. He was a little noticed at the time, that in the synthesis of
talented, lucid teacher and the university became a protein in living cells it is nucleic acid that guides
major focus of mathematical research. Hilbert con- the order in which amino acids are linked to form
tributed to analysis, topology, geometry, philoso- protein. The suggestion was correct.
phy and mathematical physics and became Hinshelwood was an expert linguist and classical
recognized as one of the greatest mathematicians scholar, and was simultaneously president of both
in history. the Royal Society and the Classical Association “ the
His earliest research was on algebraic invariants, only man, to date, to hold both offices. His own
and he both created a general theory and com- paintings were given a London exhibition a year
pleted it by solving the central problems. This work after his death and he was an expert collector of
led to a new and fruitful approach to algebraic Chinese ceramics.
number theory which was the subject of his mas- Hinshelwood shared the Nobel Prize with N N
terly book Der Zahlbericht (trans The Theory of Semenov (1896“1986) who in Moscow carried out
Algebraic Number Fields, 1897). He gathered and comparable, but complementary, studies on chain
reorganized number theory and included many reactions, with emphasis on combustion and
new and fundamental results; this became the explosive processes.
Hipparchus (of Rhodes) [hipah(r)kuhs] (c.170“
basis for the later development of class-field theory.
Abandoning number theory while many prob- c.125 bc) Greek astronomer and geographer: dis-
lems remained, Hilbert wrote another classic, covered the precession of the equinoxes, con-
Grundlagen der Geometrie (Foundations of Geometry), structed the first star catalogue and invented
in 1899. It contains fewer innovations but describes trigonometry.
the geometry of the 19th-c, using algebra to build a Stimulated by the observation of a new star in 134
system of abstract but rigorous axiomatic princi- bc, Hipparchus constructed a catalogue of about
ples. Later, Hilbert developed work on logic and 850 stars and was the first to assign a scale of ˜mag-
consistency proofs from this. Most important of all, nitudes™ to indicate their apparent luminosity, the
he developed within topology (using his theory of brightest being first magnitude and the faintest vis-
invariants) the concept of an infinite-dimensional ible to the naked eye being sixth magnitude. His
space where distance is preserved by making the scale, much refined, is still used. Comparison with

earlier records of star positions led him to the real- place of the purines in cell metabolism could lead
ization that the equinoxes grew progressively ear- to their use in the control of disease, and his
lier in relation to the sidereal year. (The equinoxes approach was well rewarded. In 1951 he and
are the twice-yearly times when day and night are Gertrude Elion made and tested 6-mercapto-
of equal length; they are the points when the eclip- purine (6MP) and found it to inhibit DNA synthesis
tic, the Sun™s path, crosses the celestial equator.) He and therefore cell division; it proved useful in the
evaluated the amount of precession as 45” of arc treatment of some types of cancer, especially leu-
per year and determined the length of the sidereal kaemia. Further work on it showed in 1959 that it
and tropical years, the latter accurate to within 6 inhibited production of antibodies in the rabbit;
minutes. Hipparchus suggested improved methods and a related compound was used from 1960 to con-
of determining latitude and longitude on the trol rejection in kidney transplantation, where the
Earth™s surface, following the work of Eratosthenes. normal body processes would treat the transplant
He constructed a table of chords, a precursor of the as a foreign protein and form antibodies against it.
sine, and is therefore credited with the invention of The work on 6MP also led Hitchings and Elion to
trigonometry. All his major writing is lost, but his the discovery of allopurinol, which blocks uric acid
work was preserved and developed by Ptolemy. production in the body and which therefore forms
Hippocrates (of Cos) [hipokrateez] (c.460“370 bc) an effective treatment for gout (which is due to uric
Greek physician: traditional founder of clinical acid deposition in the joints). Other drugs intro-
medicine. duced by the group include the antimalarial
Little is known of Hippocrates™ life with any cer- pyrimethamine and the antibacterial trimetho-
tainty, except that he taught at Cos, travelled prim, acyclovir, the first drug to be effective against
widely and had exceptional fame in his lifetime. viruses, and zidovudine, used against AIDS.
The many writings under his name must include Hitchings shared a Nobel Prize in 1988 with
work by others, since over 100 years separate the Gertrude Elion, his principal associate from the
earliest and the latest items in the ˜collection™. The 1940s onwards, and with James Black.
Hitzig, Eduard [hitsik] (1838“1907) German psychi-
best of them represent a stage where medicine was
emerging from a magical and religious basis and atrist and physiologist.
was seeking to become rational and scientific in its Although Flourens had shown in 1824 that
approach to diagnosis, prognosis and treatment. removal of parts of the brain in animals led to loss
Success in this attempt was limited, but for nearly of functions such as sight, he did not experiment
2000 years no better work was done; like on the effect of electrical stimulation of the brain
Aristotle™s work, Hippocratic ideas were to domi- and it was not seen as a source of muscular action.
nate their field and become sanctified by time. Hitzig, working as a psychiatrist in Zürich, reported
Many diseases listed in the Hippocratic Collection in 1870 that electrical stimulation of points in the
were ascribed to imbalance of the four ˜humours™ cerebral cortex of a dog produced specific move-
of the body and treatment was largely restricted to ments in the opposite side of its body. With G T
rest, diet and exercise rather than drugs. His case Fritsch (1838“97) he identified five such centres in
histories are admirably concise, and many of his the region now called the motor area, and such
descriptions and comments are still valid. studies to relate movement to a map of the brain
His, Wilhelm (1831“1904) Swiss anatomist and phys- were continued by him and others into the 20th-c.
iologist: introduced the microtome. Hitzig was less successful in his attempts to iden-
His qualified in medicine in 1855, and taught tify the site of abstract intelligence in the frontal
anatomy at Basle and later at Leipzig. His great lobes of the brain.
Hodgkin, Sir Alan Lloyd (1914“98) British neuro-
practical innovation was the microtome for cutting
very thin serial sections for microscopy (1866). He physiologist: major contributor to understanding
used it especially in his study of embryos; he gave of nerve impulses.
the first accurate description of the human As a student of biology and chemistry in Cam-
embryo. His son, also Wilhelm (1863“1934), first bridge, Hodgkin became interested in the basis of
described the specialized bundles of fibres in the nervous conduction, and he found by accident that
heart, ˜the bundles of His™, which are part of its elec- it was easy to obtain single nerve fibres from a
trical conducting mechanism. shore crab and that these could be used in experi-
Hitchings, George Herbert (1905“98) US pharma- ments despite their small size (diameter about
cologist: deviser of new drugs. 35 µm). In the USA in 1938 he was impressed by the
After graduating in chemistry at Washington and possibility of using larger nerve fibres from the
Harvard, Hitchings worked in universities for 9 squid. Some squids (the genus Loligo) are half a
years before he joined the Wellcome company in metre long and highly active, and have giant nerve
1942 and spent his main career there. He was fibres up to 1 mm in diameter.
notably successful in devising new drugs; in 1942 It had long been known that a nerve impulse is
he began a programme of pharmacological study of electrical and that a major nerve fibre (axon) acts
the long-known group of purine compounds, as a cable, but detailed knowledge was much
which had first been made from uric acid and advanced by the work of Hodgkin and his col-
whose chemistry had been intensively examined by leagues, especially A F Huxley (1917“97). Their
Baeyer and E Fischer. Hitchings argued that the study of the squid axon began in 1939, was inter-
Hoff, Jacobus Henrikus van ™t

rupted by their war service, and continued after and remained there. She married the historian
1945. They were able to insert a fine microelectrode Thomas Hodgkin in 1937.
into an axon and place a second electrode on the Dorothy Hodgkin developed the X-ray diffraction
outer surface of its surrounding membrane. Even method of finding the exact structure of a molecule
in a resting state there is a potential difference (originally devised by the Braggs) and applied it to
between the electrodes: the negative ˜inside™ has a complex organic molecules. Among her most strik-
resting potential compared with the positive exte- ing successes were the antibiotic penicillin, whose
rior surface. When an impulse passes, this is structure she deduced in 1956 (before it had been
reversed by the action potential for about a mil- deduced by purely chemical methods), and vitamin
lisecond; the nerve impulse is a wave of depolariza- B12, lack of which leads to pernicious anaemia. This
tion passing along the axon. Hodgkin developed a vitamin has over 90 atoms in a complex structure,
detailed theory of the origin of this membrane and her analysis in 1956 (after 8 years work) was a
potential, relating it to the presence of sodium and high point for X-ray methods. Until then, comput-
potassium ions and their distribution across the ing aid for X-ray crystallographers was primitive
membrane. This knowledge of the biophysics of and Hodgkin used remarkable chemical intuition
nervous conduction is basic to further understand- combined with massive computation. When
ing of the nervous system, and Hodgkin and Huxley modern computers became available, she was able
shared a Nobel Prize in 1963 with J C Eccles to complete a study of insulin (with over 800 atoms)
(1903“97), who also worked on nerve transmission. that she had begun in the 1930s, and in 1972
Hodgkin became president of the Royal Society in described its detailed structure. She won the Nobel
1970, and Master of Trinity College, Cambridge, Prize for chemistry in 1964.
Hoff, Jacobus Henrikus van ™t (1852“1911) Dutch
Hodgkin, Dorothy, n©e Crowfoot (1910“94) British physical chemist: a founder of stereochemistry.
X-ray crystallographer: applied X-ray crystal analy- At the age of 17 van ™t Hoff informed his mother
sis to complex biochemical molecules. and father, a physician, that he wished to become a
Dorothy Crowfoot was born in Cairo, where her chemist; their reaction was very unfavourable.
father worked in the Education Service. Soon he Despite this, he entered Delft Polytechnic, and
moved to the Sudan, to become director of both received his diploma in 2 years rather than the
Education and Antiquities; she visited her parents usual 3. He went on to study chemistry in Leiden,
in Khartoum and always retained an interest in the Bonn and Paris. He also became intensely inter-
region and in archaeology. From an early age her ested in the philosophical ideas of Comte and
interest in chemistry (especially in crystals and Taine, in Byron™s poetry and in the biographies of
identifying minerals) competed with archaeology scientists.
and after school in England she went to Oxford and Back in the Netherlands, aged 22 and ready to
studied both subjects. She was advised to specialize begin his doctoral work, he published a paper
in X-ray crystallography, did so and then went to which founded stereochemistry. It had been known
Cambridge to work with J D Bernal (1901“71): after since Biot™s work that many organic compounds
2 years there she returned to an Oxford post in 1934 are optically active (ie rotate the plane of polarized
light). Pasteur had been able to relate this prop-
erty, for crystalline solids, to the dissymmetry of
the crystals; but interest in the organic compounds
was in their optical activity in solution. Van ™t Hoff
took up an idea of Kekul©™s (1867) that the four
groups usually linked to a carbon atom can be
expected to be equally distributed in the space
around it (a ˜tetrahedral™ distribution; see dia-
gram). Van ™t Hoff saw that, if the four groups are all
different from each other, they can be arranged
about the carbon atom in two ways; and these two
variants of a molecule are non-superimposable
mirror images of each other (stereoisomers). He
proposed that one form would rotate polarized
light to the left and the other form to the right. On
this basis a general theory of molecular shapes
could be developed and, despite some initial
doubts, his ideas of stereoisomerism were soon
shown to be both correct and fruitful. The same
ideas were offered independently by J A Le Bel
(1847“1930) soon after, but he did not develop
them. They had known one another slightly, in
Wurtz™s laboratory in Paris.
At 23 van ™t Hoff tried for a job as a schoolteacher,
but was turned down because he appeared to be a
Dorothy Hodgkin
Hofmann, August Wilhelm von

architect, was overseeing the building of the new
chemical laboratory. Young Hofmann™s first
research was on coal tar aniline (C6H5NH2) and
began the interest in organic amines which was to
prove so important. He won prizes, became
engaged to Liebig™s wife™s niece and came to
London as the first head of the new Royal College of
Chemistry in Oxford Street in 1845. He stayed for 20
years, and he and his students created organic
chemistry in England. One of these students,
Perkin, made the first synthetic dye produced on
any scale (mauve, from aniline) and founded the
British organic chemical industry. Other students,
and Hofmann himself, made a variety of new
organic dyes. From them, in turn, medicinal chem-
icals were developed.
In 1850 Hofmann showed that ammonia can be
progressively alkylated by a reactive alkyl halide to
give a mixture of amines. Thus ethyl iodide with
ammonia in a sealed container (he was a large-scale
user of champagne bottles from Windsor) gives the
ethylamines, which he represented as follows,
J H van 't Hoff
basing them on the ˜ammonia type™ in a way which
˜daydreamer™. He got a junior post in a veterinary advanced the ˜Type Theory™:
college in 1876 but 2 years later took a professor- H C2H5 C2H5 C2H5
ship in Amsterdam until 1896, when he moved to HN HN C2H5N C2H5N
Berlin. In the 1880s and later, his work on physical H H H C2H5
chemistry was as valuable as his stereochemistry. He made similar compounds from phosphine
He studied reaction rates, mass action, transition (PH3) in 1855. He moved to a professorship in chem-
points, the phase rule and especially the chemistry istry in Berlin in 1865. Hofmann was not a theorist,
of dilute solutions and the application of thermo- but he had excellent instincts as an ex-
dynamic theory to chemistry. He was awarded the perimentalist and this, combined with his use of
first Nobel Prize in chemistry, in 1901. the theory available to him, led to his high output
Hofmann, August Wilhelm von (1818“92) German of new results. The Hofmann rearrangement (1881)
organic chemist: major discoverer of new organic gives a primary amine as the organic product (via
compounds of nitrogen. an isosyanate) when an amide is heated with
Hofmann began his studies in Giessen as a law bromine (or chlorine) and alkali:
student, but attendance at some of Liebig™s chem-
istry lectures changed his interests and Liebig wel- Also named after him is the Hofmann exhaustive
comed this, perhaps because Hofmann™s father, an methylation reaction, which allows a complex





Four different atoms or groups (A, B, D, E) attached to a central carbon atom can be arranged in two different ways,
which are non-superposable mirror images. The tetrahedra are imaginary: the double lines represent bonds with the
carbon atom.
Hollerith, Herman

lation counter using sodium iodide, activated by
thallium. At Stanford he used linearly accelerated
electrons scattered by nuclei to study nuclear struc-
ture. The charge density in the nucleus was
revealed to be constant, but falling sharply at the
nuclear surface, with a radial distribution related
to the nuclear mass. Neutrons and protons were
shown to have size and shape (ie were not ˜points™)
and could be regarded as made up of charged shells
of mesons, with the total charge cancelling out in a
neutron. Hofstadter was led to predict the rho-
meson and omega-meson, both of which were later
observed experimentally. He shared a Nobel Prize
in 1961.
Hollerith, Herman [holerith] (1860“1929) US com-
puter scientist: introduced the modern punched
card for data processing.
A graduate of the Columbia University School of
Mines in New York City, Hollerith did some teach-
ing at MIT and worked on air brakes and for the US
Patent Office before joining one of his former
teachers to assist with the processing of the US
Census of 1880. By 1887 he had developed his
machine-readable cards and a ˜census machine™
that could handle up to 80 cards per minute,
enabling the 1890 census to be processed in 3 years.
A W von Hofmann
Punched cards had been used by Jacquard before
1800 to mechanically control looms, but Hollerith
nitrogen-containing organic compound to be introduced electromechanical handling and used
degraded to simpler, identifiable, products; its the cards for computation: the Hollerith code
early use was to determine structures but later it relates alphanumeric characters to the positions of
became a subject for the study of reaction mecha- holes in the punched card. After the 1890 census,
nism. Hofmann produced hundreds of research Hollerith adapted his device for commercial use
papers; he had many assistants and a large number and set up freight statistics systems for two rail-
of friends; he was married four times and had 11 roads, founding the Tabulating Machine Company
children. in 1896 to make and sell his equipment; by later
Hofmeister, Wilhelm (Friedrich Benedict) mergers this became the International Business
[hohfmiyster] (1824“77) German botanist. Machines Corporation (IBM). Hollerith™s ideas were
Hofmeister followed his father into his prosper- initially more used in Europe than in the USA, but
ous music and bookselling business in Leipzig and from the 1930s punched card methods became
in his interest in plants, and by age 27 became well widespread.
known as a botanist through his work on mosses
and ferns (cryptogams). He went on to show that
this group is related to the higher seed-bearing
plants (phanerogams), and that the gymnosperms
(conifers) lie between the cryptogams and the
angiosperms (flowering plants); this prepared the
way for a unified view of the plant kingdom. This
work was linked with his discovery of the alterna-
tion of generations between sporophyte and game-
tophyte in lower plants. He was appointed
professor at Heidelberg in 1863 and at Tübingen in
Hofstadter, Robert [hofstater] (1915“90) US physi-
cist: used electron scattering by nuclei to give
details of nuclear structure.
Graduating from New York and Princeton,
Hofstadter afterwards worked at the Norden
Laboratory Corporation (1943“6), Princeton and
Stanford (1950) with a full professorship at 39; he
was director of the Stanford high-energy physics
laboratory from 1967“74.
In 1948 Hofstadter invented an improved scintil- Robert Hofstadter
Holmes, Arthur

Holmes, Arthur (1890“1965) British geologist and physicists; the prediction of the Higgs particle
geophysicist: devised modern geological time- awaits confirmation. Veltman and t™Hooft shared
scales. the Nobel Prize for physics in 1999.
Hooke, Robert (1635“1703) English physicist: inge-
While a student in London, Holmes spent a vaca-
tion on field work in Mozambique. He contracted nious inventor of devices and of ideas then devel-
malaria which prevented him joining the army in oped by others.
1914 with his friends, who largely died in the first Born in the Isle of Wight, Hooke was intended for
year of the First World War. From 1924 he headed the church and went to Oxford as a chorister.
geology at Durham and from 1943 at Edinburgh. However, his poor health was thought to make him
Holmes pioneered the use of radioactive decay unsuited to the church and he turned to science,
methods for dating rocks, whereby careful analysis becoming assistant to Boyle in Oxford and making
of the proportions of elements formed by radioac- an improved air pump for him. From childhood on,
tive decay, combined with a knowledge of the rates Hooke was an ingenious and expert mechanic. In
of decay of their parent elements, yields an 1660 he moved to London, and was one of the
absolute age. He was the first to use the technique, founders of the Royal Society in 1662. He was made
in 1913, to systematically date fossils whose strati- curator; one of his tasks was to demonstrate ˜three
graphic (ie relative) ages were established, and was or four considerable experiments™ for each weekly
thus able to put absolute dates to the geological meeting. He later added other posts (one of these, as
time scale for the first time. A modern scale is on a Surveyor of London after the great fire, made him
p. 148. rich), but the Royal Society work helped to shape
In 1928 he suggested that convection currents Hooke™s life as a prolific experimenter whose ideas
within the Earth™s mantle, driven by radiogenic were usually fully explored by others. As he was
heat, might provide the driving mechanism for the combative, this led to many disputes on priority,
theory of continental drift, which had been notably with Newton.
advanced by Wegener some years earlier. He also In the 1660s he found Hooke™s Law: this is now
proposed that new oceanic rocks were forming often given in the form that, provided the elastic
throughout the ocean basins, although predomi- limit is not exceeded, the deformation of a material
nantly at ocean ridges. Little attention was given to is proportional to the force applied to it. He did not
his ideas until the 1950s, when palaeomagnetic publish this until 1676 (as a Latin anagram) and in
studies established continental drift as a fact. intelligible form not until 1678. Also in the 1660s,
In successive and revised editions, his Principles of he realized that a spiral spring can be used to con-
Geology (1944) has been an influential and much- trol the balance-wheel of a timepiece, but Huygens
used text book. made the first working model in 1674. Hooke
t™Hooft, Gerardus (1946“ ) Dutch theoretical was fascinated by microscopy and in his book
physicist. Micrographia (1665) he describes the use of the com-
Born and educated in the Netherlands, t™Hooft pound microscope, which he had devised. He used
studied, taught and researched in the University of the word ˜cell™ to describe the angular spaces he
Utrecht, becoming a full professor there in 1977; he saw in a thin section of cork, and since then the
has held visiting appointments in several other
countries. His work has brought many honours and
awards, including having an asteroid (9491 t™Hooft)
named after him.
As a young man of 24, t™Hooft together with his
professor Martinus Veltman (1931“ ) solved the
central problem of the time in the most fundamen-
tal area of physics “ the stuff of dreams. In the 1940s
Feynman had found a mathematical quantum
theory of electrons (quantum electrodynamics,
QED) which perfectly described their behaviour. It
works because the electron is always viewed from a
distance (known as renormalization) so that its sur-
rounding virtual particles clothe it as a cloud. In
the 1960s Glashow, Salam and Weinberg devel-
oped a quantum theory of electromagnetism and
the weak nuclear interaction; similarly this needed
a method of renormalization before it could be
used in practice. Within a year t™Hooft provided
his supervisor Veltman with a suitable method.
Together they developed theoretical techniques for
making quantitative predictions concerning elec- The first illustration of plant cells: Hooke's drawing of a
troweak interactions, borne out perfectly by exper- section of cork seen through a microscope. He named the
iment. The W and Z particles were predicted and small compartments ˜cells™. A: transverse section: B: lon-
their expected properties observed by particle gitudinal section. From his Micrographia of 1665.
Hopkins, Harold Horace

word has come to be used for the membrane-bounded lowed his Himalayan Journals (1854), Rhododendrons of
units of plant and animal life. The book includes also the Sikkim Himalaya (1849) and his seven-volume
the idea that light might consist of waves; but further Flora of British India (1872“97). He undertook further
work on this was mainly by Huygens. Also in the book expeditions to Syria and Palestine, and to the Atlas
is Hooke™s theory of combustion, which is good Mountains in Morocco. He became director of Kew
enough to make it very likely that he would have dis- Gardens, succeeding his father, Sir William J
covered oxygen if he had continued with chemistry. Hooker (1785“1865), who had created the gardens.
In the 1660s Hooke had ideas on gravity, as did many His friendship with Darwin led to his being
others, and he even suggested (in 1679) that its force instrumental, with Lyell, in presenting the joint
obeys an inverse square law. These ideas may have communication of Darwin and Wallace on the
been useful to Newton; what is certain is that origin of species to the Linnean Society and in per-
Newton™s toil and his mathematical genius suc- suading Darwin to publish The Origin of Species. He
ceeded in developing the idea brilliantly and that joined with Bentham in producing the magisterial
Newton forcefully resisted Hooke™s claims of priority. Genera plantarum (7 vols, 1862“83), giving their
Hooke had no rival as a deviser of instruments; important system of classification; and was an
the microscope, telescope and barometer were all authority on Antarctic flora. He became president of
much improved by him and his other inventions the Royal Society in 1873.
Hopkins, Sir Frederick Gowland (1861“1947)
include a revolving drum recorder for pressure and
temperature, and a universal joint. His contribu- British biochemist: made first general scientific
tion to science is unusual; he did much, but his study of vitamins.
devices and ideas were largely developed by others. Hopkins believed firmly that chemical reactions in
He certainly did more than anyone else to change living cells, although complex, are understandable
the Royal Society from a club of virtuosi to a profes- in normal chemical and physical terms. This faith,
sional body. The frequent comment that he was and his amiable forcefulness, made him ˜the father
much disliked seems to have arisen because he of British biochemistry™. His beginnings were not
quarrelled with Newton. He certainly had many indicative of his future fame. His widowed mother
friends and his large library attests to his wide chose a career for him at 17, in an insurance office.
interests. No portrait of him is known to exist. Later he worked as an analyst, especially on forensic
Hooker, Sir Joseph Dalton (1817“1911) British cases. When he was 27 he inherited some money and
botanist: plant taxonomist, phytogeographer and entered the medical school at Guy™s Hospital and
explorer. after qualifying worked with Garrod, founder of
As a young boy, Hooker™s mother described him as biochemical genetics. At 37 he went to Cambridge,
˜not very clever™ and as ˜croaky Joe™ (he suffered from but his teaching load was so great that his health
a persistent cough). Predictions based on her views broke down in 1910. He recovered fully, and his col-
would have been wrong on both counts: as an adult lege (Trinity) then gave him a research post.
he was both clever and physically tough, surviving Recovered in health, and almost 50, he began the
expeditions at extremes of both latitude and altitude. work for which he is famous, on ˜accessory food fac-
Educated at Glasgow in medicine, Hooker became tors™ (vitamins), and in 1914 became the first profes-
assistant surgeon and naturalist on Ross™s Antarctic sor of biochemistry in Cambridge. His classic studies
expedition of 1839“43 on board HMSS Erebus and on nutrition showed that young rats failed to grow
Terror. His books Flora Antarctica, Flora Novae-Zelandiae on a diet of pure protein, carbohydrate, fat, salts and
and Flora Tasmaniae were a result. He travelled water; but the addition of small amounts of milk (2“
widely in India, Palestine and the United States, 3 ml per rat per day) caused them to thrive. The ˜vit-
where he spent 3 years collecting plants. There fol- amin hypothesis™ followed, as did much work on vit-
amins in Cambridge and elsewhere. Hopkins
worked also on the biochemistry of muscle, on en-
zymes, on -SH groups and on glutathione. He shared
a Nobel Prize with Eijkmann in 1929.
Hopkins, Harold Horace (1918“94) British optical
Hopkins was educated at Leicester and London
and was professor of applied optics at Reading from
1967“84. After N S Kapary™s early proposals in 1955,


light path
source of lightray

Section through an optical fibre; the cladding has a lower
refractive index than the core
Joseph Hooker, aged 34
Panel: Scientific societies

SCIENTIFIC SOCIETIES demonstration at each meeting; they acquired some
apparatus (such as Boyle™s ¬rst air-pump and
Scienti¬c societies have played a major part in Newton™s reflecting telescope), bent their minds to
science. The exchange of ideas within and between anything new or strange (excluding religion and
societies encourages experiment and the testing of politics), such as blood transfusion or the habits of
theory; an isolated researcher can too easily become ¬sh; exchanged research results with societies
complacent. Some societies were also engaged from abroad and published their own in their Philosophical
their beginning in the organization and funding of Transactions. To this day the Royal Society retains its
science and in the selection of research projects, seniority in British science, providing the highest-
such as those directed to improving ship design and level advice to government, and electing to its fellow-
navigation at sea in the 17th-c. ship only the most distinguished professional and a
Usually classed as the ¬rst scienti¬c society, few amateur scientists (under 1000 Fellows in all,
the Accademia dei Lincei (Academy of the Lynxes) including about 3% women) in Britain, and a handful
was founded in 1609 by the 18-year-old Count working abroad.
Federico Cesi in Rome; so devoted to scienti¬c study The Parisian Acad©mie Royale des Sciences,
that they swore to remain unmarried, the ˜lynxes™ founded by King Louis XIV in 1666 (after 1816 the
were named for their claimed clear-sightedness. Acad©mie des Sciences) was funded by the state for
Their membership rose to 32 and included GALILEO, state purposes. Its very select and active
but the society failed to survive Cesi™s death in membership included LAVOISIER. The talented young
1630. artillery of¬cer Napoleon Bonaparte, elected in 1797,
The Royal Society of London for the Improve- was an active member and later its patron until his
ment of Natural Knowledge was of¬cially founded in power ended in 1814. Academies on the Paris model
1660, but its key ¬gures had met in London, and later followed in Berlin (1700), St Petersburg (1725) and
in Oxford, from about 1645. It was encouraged (but Stockholm (1739).
never funded) by the newly-restored King Charles II The American Philosophical Society, founded
and its membership included BOYLE, HOOKE, LOWER, in Philadelphia in 1743, also covered science and was
NEWTON and WALLIS. Independent of the state, it modelled on the Royal Society rather than the
elected its own Fellows, and soon included many European academies, encouraging the amateur
gentleman-amateurs, such as Samuel Pepys the enthusiast. It stemmed from BENJAMIN FRANKLIN™S
diarist. Its only resources were the Fellows™ shilling-a- Junto, a secret literary and scienti¬c club active from
week subscriptions, often in arrears. The Society 1727. (It was not the oldest in the USA: that was
appointed a Curator (Hooke), who had to provide a probably the Boston Philosophical Society, founded

Hopper, Grace (Murray) (1906“92) US computer
work by many groups greatly advanced fibre-optics,
with contributions by A C S Van Heel and by programming pioneer.
Hopkins of high value. Optical fibres of plastic or Grace Hopper graduated from Vassar College in
glass (pure silicon dioxide is suitable) are used; they mathematics and physics, received a PhD from Yale
guide light by trapping it through total internal and taught at Vassar before joining the US services
reflection. Their diameter is of the order 0.01 mm in the Second World War. In 1943 she joined the
and the light-carrying core has an outer cladding to Naval Reserve and remained a reservist for the rest
confine the light. A bundle of such fibres is used in of her career. Having worked for the wartime navy
flexible endoscopes, which can be inserted through using large-scale pre-electronic calculators, she
natural or surgical apertures to give direct viewing joined the Eckert-Mauchly Computer Corp. in 1949:
within the body, of great value in medical diagno- thereafter she completed the first compiler (A-O,
sis and in ˜keyhole™ surgery. the software for the Univac computer) in 1952,
Optical fibres also find application in communi- developed Flow-Matic (a language suitable for busi-
cation systems; undersea fibre-optic cables for tele- ness data processing) in 1958 and provided a major
phone services cross the Atlantic and Pacific input to the development of COBOL, a high-level
oceans. Light signals, like electrical signals, can be computer language. She was recalled to the navy in
transmitted and processed in either analogue or 1967 to help standardize its computer languages.
digital form. Optical fibres have advantages over She had some unusual distinctions; she was the
electrical wiring in their smaller size and lower first computer scientist to be named Man of the
weight and in their freedom from electrical inter- Year (in 1969), and she was the oldest officer on
ference. A variety of information-carrying uses will active US naval duty when she retired in 1986,
certainly continue to develop. having been promoted to rear admiral in 1985.
Hoppe-Seyler, Ernst Felix [hopuh ziyler] (1825“
As well as his major work on flexible endoscopes,
Hopkins did much to develop the variable zoom 95) German biochemist: first to isolate nucleic acid.
lens now widely used by photographers and in tele- Orphaned early, Hoppe-Seyler was brought up by
vision cameras. his brother-in-law and followed him by studying
Hounsfield, Sir Godfrey Newbold

by Increase Mather in 1683, but which soon expired.) Linnean Society (1788) for botany and the
An early project of the American Philosophical Geological Society of London (1807). The
Society was the ¬rst accurate measurement of the Astronomical and Chemical Societies began in
Earth“Sun distance, by observing the transit of Venus London in the 19th-c, with very many other special-
in 1769. ized societies being formed in the USA. Through their
The American Civil War made evident a need for a publications and meetings they nurture expertise
National Academy of Sciences and this was duly and publicize new discoveries for information and
created in 1863. A later conflict, the ˜Cold War™ of the discussion.
1950s, generated the National Aeronautic and Space The lack of encouragement of women in scienti¬c
Agency (NASA) in 1957, which, although not a societies is noteworthy. Before the First World War
scienti¬c society, has been linked with increasingly the poor quality of the education in science available
dramatic explorations of the solar system and whose to women excluded all but a very few from senior
scienti¬c effort in support of government intentions positions and if they achieved original work in
recalls in scale the Manhattan Project of the Second science despite the dif¬culties, it tended to be
World War. eclipsed through their position as someone™s wife,
Local scienti¬c societies existed from the 18th-c in sister, daughter or assistant and subsumed into a
Europe and the USA. One such was the Lunar male™s publication. After the Second World War the
Society, which met in the English Midlands in the proportion of women graduating in science rose
1780s and was so called because its monthly meet- steadily, and membership of scienti¬c societies
ings were held on the night of the full moon so it could became more open to them, but a gender bias has
light members home. These included PRIESTLEY; Josiah remained. At senior levels in university, industry and
Wedgwood (1730“95) the industrialist potter; WATT; the learned societies the proportion of women
Matthew Boulton (1728“ 1809), his partner and ¬rst remains low; they have made up about 3% of the
manufacturer of steam engines; Erasmus Darwin Royal Society fellowship for over 25 years. More
(1731“1802), poet, engineer, medical man and encouragingly, the US National Academy of Sciences
grandfather of CHARLES DARWIN; and William Murdock has 4.7% women, and for the last 5 years 10.7% of
(1754“1839) the inventor of gas lighting. Local the newly elected members have been female. In
societies such as the Liverpool Astronomical Society 1991 the embryologist ANNE MCLAREN became
(1882), tapped the enthusiasm and expertise of Foreign Secretary of the Royal Society, the ¬rst
amateurs to good effect, as did the comparable local woman to hold an of¬ce in its 330-year history.
scienti¬c societies of the USA.
Specialized societies followed the model of the

medicine. He only practised briefly, however, and achieved a remarkable range of accurate measure-
after some research training with Virchow he ments, especially in the solar system.
Hounsfield, Sir Godfrey Newbold (1919“ )
worked in Tübingen and later Strasbourg, mainly
on the use of chemical and physical methods in British physicist: developed first X-ray tomographic
physiology. He isolated haemoglobin, the red pig- body scanner.
ment of blood, and studied its reaction with carbon Hounsfield received no formal university educa-
monoxide; he was also the first to obtain pure tion but studied at the City and Guilds College
lecithin, and he studied oxidation in animal tissues and at the Faraday House College for Electrical
and enzyme action. His Swiss pupil J F Miescher Engineering in London. In 1951 he joined Electrical
(1844“95) first isolated a nucleic acid, in 1869, and and Musical Industries (EMI), becoming head of the
later Hoppe-Seyler extended this work. He founded medical research division.
in 1877 a journal for physiological chemistry, edit-
ing it in a characteristically autocratic way, and
was a major figure in establishing classical bio-
chemistry as a separate branch of science.
Horrocks, Jeremiah (1618“41) English astronomer.
Educated at Cambridge University but self-taught
in astronomy, Horrocks became a curate at Hoole,
in Lancashire; a brilliant amateur astronomer, he
achieved a great deal in his short life. He is particu-
larly remembered as the first observer (1639) of a
transit of Venus across the face of the Sun, which he
had predicted using Kepler™s Rudolphine tables.
From the transit the value of planetary distances
can be calculated by Kepler™s laws; hence its impor-
tance. In the 2 years before his death, Horrocks Sir Geoffrey Hounsfield
Hoyle, Sir Fred

Independently of Cormack, Hounsfield devel- a short career in law he turned to astronomy, work-
oped the technique of X-ray computer-assisted ing for most of his life at Mount Wilson
tomography (CAT), whereby high-resolution Observatory. Using the 100 in telescope at Mount
images of the soft body tissues (which are normally Wilson, Hubble was able in 1923 to resolve the neb-
almost transparent to X-rays) are built up by com- ulous outer part of the Andromeda galaxy into indi-
puter from many measurements of the absorption vidual stars, obtaining a distance of 900 000 light
of X-ray beams in different directions through the years for several Cepheid variable stars he found
body. In the early 1970s he developed the first com- there. Together with further work this proved for
mercial CAT body scanner at EMI; such machines the first time that what were then thought of as
are now an invaluable medical tool. Hounsfield has ˜spiral nebulae™ were in fact spiral galaxies, and lay
continued to lead research into medical imaging, well beyond our own Galaxy. In 1929 he was able to
pursuing in particular the use of magnetic reso- measure the recessional velocities of 18 galaxies,
nance imaging (MRI) techniques. In 1979 and discovered that these velocities increased in
Hounsfield shared the Nobel Prize for physiology or proportion to their distance from Earth. This rela-
medicine with Cormack. tionship (v = Hd) is now known as Hubble™s Law, the
Hoyle, Sir Fred (1915“2001) British cosmologist and constant of proportionality being Hubble™s con-
astrophysicist: jointly proposed the steady-state stant (H). This work gave the first direct evidence
theory of the universe. supporting the idea of an expanding universe, a
Even as a small boy in a Yorkshire village, Hoyle concept that had been proposed a few years earlier
was ˜at war with the system™ and became a long-term by the cosmologists Friedmann and Lema®tre and
truant. Later he had problems in entering is now fundamental to our understanding of the
Cambridge. In 1973 he resigned his chair after dis- universe. Hubble™s observations meant that two
putes with the university authorities. fundamental quantities of the universe could be
Together with Gold and Bondi, Hoyle proposed calculated for the first time: its ˜knowable™ size, or
the steady-state theory for the origin of the uni- the distance at which the recession velocity reaches
verse in the 1950s. This theory assumes that the the speed of light, which is about 18 billion light
universe is not only homogeneous and isotropic in years; and the age of the universe, which Hubble
space, but also unchanging with time. The known himself estimated as 2 billion years, although
expansion of the universe is explained by the con- modern values range between 12 and 15 billion
tinuous and spontaneous creation of matter to years. Hubble also introduced a widely used system
maintain the mean mass density at a constant of classification for the shape of galaxies.
value. Newer evidence has left that theory with few It is interesting that Hubble was always cautious
supporters. Hoyle also suggested (in 1957, with W A in interpreting Hubble™s Law of 1929, which is
Fowler (1911“95) and Geoffrey and Margaret based on the spectroscopic redshift and Doppler™s
Burbidge) how elements heavier than helium and principle, as meaning that the universe is expand-
hydrogen might have been created by nuclear syn- ing. Hubble™s rather ambiguous writings on this
thesis in the interior of stars, eventually being imply that possibly the observed increase in red-
ejected into space and incorporated into new stars shift with distance had other causes; and bearing in
formed from clouds of interstellar matter. All this mind the many novel views advanced in cosmology
work has led to fruitful advances, directly or through since 1929, he was probably right to be prudent.
their effect on others: and the ˜B2FH paper™ is now Hubel, David Hunter (1926“ ) Canadian“US neu-
accepted as a major contribution to cosmology. rophysiologist: investigator of the basis of visual
More recently Hoyle, with Geoffrey Burbidge and perception.
J V Narlikar, developed a quasi-steady-state theory, Hubel qualified in medicine at McGill University,
in which the creation of matter is not continuous Montreal, and from 1959 worked at Harvard. With
but intermittent. These creation events, the theory T N Wiesel (1924“ ) he did much to aid under-
suggests, are linked with strong gravitational fields standing of the mechanism of visual perception at
and can occur on various scales, with our part of the cortical level, using microelectrodes and
the universe being created about 15 billion years modern electronics to detect the activity of indi-
ago. These ideas did not find wide support. vidual neurones, especially in area 17 of the visual
He was also a believer in an extraterrestrial origin cortex. The cells of this striate cortex lie in several
for life, suggesting that biological molecules such layers arranged in columns, which run through the
as amino acids are synthesized in space on dust par- thickness of the cortex (a few millimetres). Hubel
ticles. His view that infective agents such as viruses and Weisel found that stimulation of cells on the
can arrive from space found little support. He, how- retina by light causes excitation of particular cells
ever, was notably successful as a theorist and as in the striate cortex. The cell activation in the
a writer both of popular science and of science cortex by visual stimulation is very specific; some
fiction. cells respond to spots of light, others to a line whose
Hubble, Edwin Powell (1889“1953) US astronomer tilt is critical, so that a change of 10° in its angle
and cosmologist: discovered expansion of universe greatly alters the response. Still others respond
and measured its size and age. only to specific directions of movement or to spe-
Hubble was trained in Chicago and Oxford in law; cific colours. The visual cortex has become the best-
he was also a distinguished athlete and boxer. After known part of the brain through studies of this
Humboldt, Alexander, Freiherr von

kind. Hubel and Wiesel established in addition that trum. He correctly interpreted this as being due to
many of the connections responsible for these spe- the Doppler effect, obtaining a recessional velocity
of about 40 km s “1 (25 miles per second), and pro-
cific response patterns are present already at birth
but may be modified or even destroyed if the young ceeded to measure the red shifts of many other
animal is visually deprived. These results have had stars. With the advent of the gelatine dry plate he
an important influence on treatment of congenital pioneered the technique of spectroscopic photog-
cataracts and strabismus (squint). Hubel and Wiesel raphy, from 1875. (The particular advantage of pho-
shared a Nobel Prize in 1981. tography over the eye is that a faint image can be
Hückel, Erich (1896“1980) German physicist and ˜accumulated™.)
Hulst, Hendrik Christofell van de (1918“ )
theoretical chemist: developed molecular orbital
theory of bonding in organic molecules. Dutch astronomer: predicted interstellar 21 cm
Hückel™s study of physics at Göttingen was inter- hydrogen emission.
rupted by the First World War, when he spent 2 Educated in Utrecht and in the USA, van de Hulst
years on aerodynamics before returning to finish became director of the Leiden Observatory. In 1944
his course. He worked as assistant first to the math- he suggested that interstellar hydrogen might be
ematician Hilbert and then to Born, but he did not detectable at radio wavelengths, because of the
like the work and he also wished to travel. He 21 cm radiation emitted when the orbiting elec-
joined his former teacher Debye at Zürich and tron of a hydrogen atom flips between its two pos-
began working on what is now known as the sible spin states. Because of the war it was not until
Debye“Hückel theory of electrolyte solutions. This 1951 that such emissions were first detected, by
assumes that strong electrolytes are fully dissoci- Purcell and H I Ewen (1922“ ). The technique has
ated into ions in solution, and calculates properties since proved invaluable in detecting neutral hydro-
(such as electrical conductivity) for dilute solutions gen in both our own and other galaxies, as well as
on this basis. Then, after a major illness, he worked in interstellar space. Since the 21 cm wavelength is
on colloid chemistry, first with his father-in-law not absorbed by interstellar dust, it has also
Zsigmondy and later with F G Donnan (1879“1956) enabled a much better picture of the centre of our
in London, and then moved to Copenhagen to work Galaxy to be built up where optical methods have
on quantum theory with Bohr. The latter sug- failed.
Humboldt, (Friedrich Wilhelm Heinrich)
gested that Hückel should try to calculate proper-
Alexander, Freiherr (Baron) von (1769“1859)
ties of the CC double bond by wave mechanics.
Hückel classified the electrons making up such German explorer: pioneer of geophysics and mete-
bonds as σ (sigma) and π (pi) types on a symmetry orology.
basis and was able to make useful calculations of Humboldt had wide scientific interests and a pas-
bond properties. Hückel molecular orbital (HMO) sion for travel, and was wealthy enough to indulge
theory has been widely applied to organic mole- both his enthusiasms. His father, a Prussian soldier,
cules. One result is Hückel™s rule, which proposes wished him to enter politics, but the boy preferred
that aromatic stability will be shown by planar to study engineering; while doing so he was
monocyclic molecules in which all the cyclic atoms attracted to botany and moved to Göttingen to
are part of the π-system only if the number of such study science. He seems to have been happiest with
π-electrons is 4n + 2, where n is an integer. The rule geology, and spent 2 years at a school of mining
has provoked much fruitful study of molecules pre- before working as a mining engineer, when he
dicted by the rule to show ˜aromaticity™. Hückel™s devised and tested safety lamps and rescue appara-
work on such compounds probably began with a tus. Then in 1796 he inherited enough money to
suggestion from his elder brother Walter, an travel, but the Napoleonic Wars frustrated him
organic chemist. From 1937 Erich was professor of until 1799, when he began an epic exploration of
theoretical physics at Marburg. central and south America. He covered over 6000
Huggins, Sir William (1824“1910) British often dangerous miles with his friend, the botanist
astronomer and astrophysicist: pioneered stellar A Bonpland (1773“1858), before returning to Eu-
spectroscopy and discovered stellar red shifts. rope with a large collection of scientific specimens
Huggins was a wealthy amateur who used his pri- and observations after 5 years of absence. Analysis
vate observatory in South London to study a full of his results, along with some diplomatic mis-
range of celestial objects. Like Lockyer, he was sions, kept him busy for the next 20 years. His wide-
attracted by spectrum analysis and its possible use ranging interests were largely in geophysics,
in astronomy; aided by his wife Margaret meteorology and geography. He studied the Pacific
(1848“1915), Huggins pioneered the study of the coastal currents, and was the first to propose a
spectra of stars, finding them to contain elements Panama canal. He introduced isobars and isotherms
already known on Earth and in the Sun. He went on on weather maps, made a general study of global


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