. 5
( 21)


to become known as the Hertzsprung“Russell diagram.

Cornforth, Sir John

(CT), is the basis for the modern body scanners much of Coulomb™s early work was concerned with
which have become an invaluable medical tool. engineering problems in statics and mechanics. He
Cormack and Hounsfield shared the Nobel Prize for showed that friction is proportional to normal pres-
physiology or medicine in 1979. sure (Coulomb™s Law of Friction) and introduced
Cornforth, Sir John (Warcup) (1917“ ) Australian the concept of the thrust line. However, he is pri-
organic chemist. marily remembered for his work on electrical and
Trained in Sydney and Oxford, where he worked magnetic attraction and repulsion. From 1784
with Robinson, Cornforth had originally chosen to onwards he conducted a series of very delicate
work in chemistry partly because from age ten he experiments, using a torsion balance he had
became deaf, which excluded many other possible invented himself and capable of detecting forces
equivalent to 10“5 g. He discovered that the force
careers. Despite not hearing any lectures he had a
prize-winning student career, winning an 1851 between two charged poles is inversely propor-
Exhibition to Oxford: the only other such award tional to the square of the distance between them
was to Rita Harradence, another organic chemist and directly proportional to the product of their
from Sydney. They travelled to Oxford on the same magnitude (Coulomb™s Law of Force). This was a
ship, arriving in England just as war started. They major result, paralleling Newton™s law of gravita-
married in 1941, and she became his principal co- tional attraction. The SI unit of electric charge, the
worker for the next 30 years (and always his com- coulomb (C), is named in his honour. It is the charge
municator with the hearing world; his deafness, crossing any section of a conductor in which a
due to otosclerosis, was total). The pair were part of steady current of 1 ampere flows for 1 second.
Coulson, Charles Alfred (1910“74) British math-
the Oxford team, led by Robinson, who had worked
during the Second World War on penicillin. After ematician: a founder of modern theoretical chem-
the war they worked at the National Institute for istry.
Medical Research in London, and in 1951 achieved Coulson was unusual in holding professorships
(simultaneously with Woodward) the first total in theoretical physics (King™s College, London
synthesis of steroids. He was a leading member of 1947“52), applied mathematics (Oxford 1952“72)
the MRC group, which found by ingenious use of and theoretical chemistry (Oxford 1972“4). He also
isotopically labelled carbon and hydrogen atoms, played a major role in creating the third of these
how the molecule of cholesterol is synthesized in subject areas and wrote useful books on Waves and
the body. They showed that the C27 carbon skeleton on Electricity. He also published on meteorology,
(made up of three fused six-atom rings and one five- biology and theology.
atom ring) is built up in a complex series of enzyme- Coulson developed the application of quantum
regulated stages, entirely from two-carbon (acetyl) mechanics to the bonds between atoms in mole-
fragments. Cholesterol is a key compound in the cules. These bonds originate in the interaction
steroid group (which includes sterols, vitamins D, between the outer electrons of the bonded atoms.
bile acids, and hormones). It is essential in animal He showed how to calculate those molecular bond-
metabolism, although deposits of it in the arterial lengths and energies of interest to chemists. The
system are a major health hazard: only about 10% method he used is called molecular orbital (MO)
of body cholesterol is taken in with the diet, and theory (1933). He also showed how bonds interme-
90% is synthesized in the liver. diate between single and double bonds could arise
From 1962 to 1975 Cornforth was with Shell (1937). This then allowed him and H C Longuet-
Research, and thereafter he was Royal Society Higgins (1923“ ) to explain the delocalized (ie
research professor at the University of Sussex. multicentre) bonding in such aromatic molecules
During this time his main work was on enzyme reac- as benzene. In 1952 he wrote his classic textbook
tions. The idea of a lock-and-key relation between Valence, which proved valuable in the development
molecules in biochemical reactions goes back to of the subject. Later he studied bonding in mole-
Ehrlich, but its refinement to establish the details cules of biochemical importance.
of molecular shape involved in enzyme reactions Coulson influenced his generation not only as a
owes much to Cornforth. He shared the Nobel Prize theoretical chemist, where his methods have proved
for chemistry in 1975 with V Prelog (1906“98) who of great value, but also as a leading Methodist and
had worked in related areas of stereochemistry. writer on science and Christianity. He was chair-
Coulomb, Charles (Augustin de) [koolµb] (1736“ man of the charity Oxfam from 1965“71.
Couper, Archibald Scott [kooper] (1831“92) British
1806) French physicist: discovered inverse square
law of electric and magnetic attraction. organic chemist: pioneer of structural organic
Coulomb trained as a military engineer and chemistry and victim of misfortune.
served in Martinique for 9 years. He eventually After leaving school Couper studied a variety of
returned to France as an engineering consultant subjects; classics at Glasgow and philosophy at
but resigned from the Army altogether in 1791 and Edinburgh were separated by visits to Germany,
moved from engineering to physics. During the where he learned German speedily. As the son of a
French Revolution he was obliged to leave Paris, but wealthy manufacturer, he seems to have studied
returned under Napoleon and became an inspector- whatever interested him; he concentrated on
general of Public Instruction. chemistry somewhere between 1854 and 1856. By
Not surprisingly in view of his military service, 1858 he had spent 2 years in Paris, researching on
Crick, Francis

benzene compounds, and early in that year he com- computers are invaluable for complex scientific
pleted a paper ˜On a New Chemical Theory™ and and some governmental work.
asked Wurtz to present it at the French Academy. His circuit designs have very short electrical con-
However, Wurtz delayed and Kekul© published his nections between internal components to increase
theory of organic structure shortly before Couper™s their speed. After founding the Cray Computer
paper appeared. Couper™s views were similar, but Corporation in Colorado Springs he continued his
much more clearly expressed. He argued that dominance in the supercomputer field with his
carbon had a valence of 2 or 4; and that its atoms work on the gallium-arsenide-based Cray 3. His pas-
could self-link to form chains. He showed chemical sion for supercomputer design has been legendary.
structures with broken lines to connect bonded Brilliant and eccentric, he had built an automatic
atoms and he saw these structures as representing telegraph machine when he was 10 years old. Later
chemical reality; in these respects his ideas were in life, he built a new sailboat each winter, and
ahead of Kekul©™s. However, the latter had priority burned it inexplicably before the next winter.
Crick, Francis (Harry Compton) (1916“ ) British
of publication and forcefully pressed his superior-
ity. Couper quarrelled with Wurtz, returned to molecular biologist: co-discoverer with Watson of
Edinburgh and soon his depression led to illness. double-helix structure of DNA.
He never recovered, although he lived in mental The outstanding advance in the life sciences in
frailty for another 33 years, ignored as a chemist. this century has been the creation of a new branch
Credit for the idea of a ring structure for benzene of science: molecular biology. In this, Crick has
is rightly given to Kekul© (1865), but it is hardly been a central figure and its key concept, that the
known that the first ring structure for any com- self-replicating genetic material DNA has the form
pound was proposed 7 years earlier by Couper, for a of a double helix with complementary strands, is
heterocyclic reaction product from salicylic acid due to him and J D Watson.
and PCl5. Crick graduated in physics in London but his first
Modern structural formulae were first widely research was interrupted by war service, working on
used by A C Brown (1838“1922) of Edinburgh from naval mines. After the war he was attracted to
1861, who included double and triple bonds Cambridge and to biology and by 1949 was with the
between carbon atoms. Cambridge Medical Research Council Unit, then
Cousteau, Jacques (Yves) [koostoh] (1910“97) housed in the Cavendish physics laboratory. His field
French oceanographer: pioneer of underwater of expertise was the use of X-ray crystal diffraction
exploration. methods (originally devised by the Braggs) to exam-
Cousteau was in the French navy when the ine the structure of biopolymers. The overall head of
Second World War broke out, having graduated the Cavendish Laboratory was then Sir Lawrence
from the École Navale at Brest. Following distin- Bragg. In the 1950s and under his patronage, the
guished service in the Resistance (during which team led by Perutz and including J C Kendrew
time he designed and tested his first aqualung) he (1917“97), Watson, H E Huxley, Crick and later
was awarded the L©gion d™Honneur and the Croix Brenner were to have as dramatic an effect on mol-
de Guerre. After the war he became head of the ecular biology as Rutherford™s team had on particle
Underwater Research Group of the French navy and physics in the 1930s, and in the same building.
afterwards made many notable advances in the tech-
nology and techniques of underwater investigation,
constructing a diving saucer capable of descending
to 200m for long periods and working with Auguste
Piccard (1884“1962) on the design of the first bathy-
scaphes. He set a world record for free diving in 1947,
but is probably best known for pioneering underwa-
ter cinematography and for his studies of marine life.
Cray, Seymour R (1925“96) US computer engineer:
leading designer of supercomputers.
After leaving school in 1943, Cray joined the US
Army and fought in Europe and the Philippines
before studying electrical engineering at Minnesota,
followed by postgraduate mathematics. Cray worked
on UNIVAC I, the first commercially available elec-
tronic computer, and went on to design large-scale
computers for Control Data Corporation, which he
had helped to found. In 1972 he left them to found
Cray Research Inc., and to design the Cray-1 (1976),
price $8 million, the world™s fastest computer,
which could perform 240 million calculations per
second. Later models were even faster; the Cray-2
(1985), supercooled by liquid nitrogen, achieved
1200 million calculations per second. Such super- F H C Crick, in about 1954.
Crile, George Washington

Crick had devised a general theory that would
show whether a given X-ray pattern was due to
a helical structure; and his friendship with
AT M H F Wilkins (1916“ ) at London gave him lim-
ited access to the X-ray pictures made there by
Wilkins™s colleague, Rosalind Franklin. With all
this in mind, Crick and Watson built their models
TA and in 1953 focused on a model in the form of a
CG double helix, with two DNA chains. It could accom-
modate all known features of DNA, with acceptable
interatomic angles and distances, and would
accord with Franklin™s observed X-ray diffraction
TA pattern. The sequence of atoms in them give the
AT DNA chains a direction, and the pair of chains form-
ing the double helix run in opposed directions.
Also, the helices are right-handed. The model had
its sugar and phosphate chains on its outside and
CG the bases (linked in pairs, A with T, C with G) on the
CG inside (see diagram). The model explains how DNA
replicates, by the uncoiling of its double-helical
A strands, with these strands then acting as tem-
G plates. It also suggested how genetic information
C could be encoded, by the sequence of bases along the
chains. Crick proposed as a ˜central dogma™
the scheme DNA ’ RNA ’ protein, with the first
G arrow representing transcription and the second rep-
resenting translation. (The conversion DNA ’ DNA,
GC old TA
shown in the diagram, is known as replication.)
TA Crick and Watson had found the broad answer to
new the question ˜how do genes replicate and carry
GC information?™ and in the succeeding years most
work on molecular biology has been directed to
confirming, refining and extending these ideas.
Crick himself has done much in this area, for exam-
ple in work with Brenner demonstrating that the
code is read in triplets of bases (codons) each defin-
ing one specific amino acid used to make a protein,
and in showing that adjacent codons do not over-
DNA replication, following Watson and Crick. The two
lap. He also studied the structure of small viruses
strands of the double helix separate, and a daughter
and collagen, and the mechanism by which tran-
strand is laid down alongside each with a constitution
scription and translation occurs; and he has offered
determined by the base sequence of its parent strand.
novel ideas on the origin of life on Earth and on the
In 1951 Watson joined the group. He was 23, a nature of consciousness. He worked mainly in
zoologist with experience of bacterial viruses and Cambridge until 1977 when he moved to the Salk
an enthusiasm for genetics. He and Crick quickly Institute in San Diego, CA. He shared the Nobel
became friends; they shared an optimistic enthusi- Prize for physiology or medicine in 1962 with
asm that it should be possible to understand the Watson and Wilkins.
Crile, George Washington (1864“1943) US sur-
nature of genes in molecular terms, and in under 2
years they were to succeed. Important background geon: advanced knowledge of surgical shock and
material was available for them. There was good methods for reducing this.
evidence from Avery™s work that the DNA of genes A graduate of Ohio Northern University, Crile
formed the key genetic material. A R Todd had studied in Europe and afterwards practised in
shown that DNA consists of chains of sugar Cleveland, OH. He was an early user of blood trans-
residues (deoxyribose) linked by phosphate groups fusion in surgery, with his own method of direct
and carrying base molecules (mainly of four types) linkage for this. He was particularly interested in
attached to the sugar rings. Chargaff had shown surgical shock, in which bodily functions (cardiac
that the number of these bases had a curious ratio output, blood pressure, temperature, respiration)
relation. Helical structures had been met with; are depressed with possibly fatal results. His animal
Pauling had shown, as had Crick, that the protein experiments and studies on patients led him to
keratin consists of chains of protein arranged in emphasize shock prevention; he advocated greater
helical form; Pauling, like Crick, was an enthusiast care in anaesthesia, the use of an epidural anaes-
for making molecular models as an aid to deducing thetic where possible, the maintenance of blood
possible structures. volume (eg by transfusion) and the monitoring of
Curie, Marie

blood pressure during surgery. These techniques clue he was able to isolate a new element, thallium;
improved control in general surgery and became he studied its rather strange chemistry and mea-
routine; their effectiveness is not reduced by Crile™s sured its relative atomic mass. The accurate weigh-
incorrect belief that surgical shock originates in ings for this (done in a vacuum) led to his invention
the nervous system. of the Crookes radiometer, in which four light
Cronin, James Watson (1931“ ) US particle physi- vanes, each with one face blackened, are pivoted in
cist: demonstrated the non-conservation of parity a glass container with gas at a low pressure. In light,
and charge conjugation in particle reactions. the vanes rotate; the device helped to confirm the
Cronin was educated at the University of Chicago, kinetic theory of gases. He also studied electrical
later working at Brookhaven National Laboratory discharges in vacuum tubes, already studied by J
and Princeton University before returning to Plücker (1801“68) and J W Hittorf (1824“1914).
Chicago as professor of physics in 1971. Crookes found that the ˜cathode rays™ travelled in
Lee and Yang had shown in 1956 that parity was straight lines, could cast shadows, heat obstacles
not conserved in weak interactions between sub- and be deflected by a magnet; he concluded they
atomic particles. In 1964 Cronin, together with V L were negatively charged particles but this found
Fitch (1923“ ), J Christensen and R Turlay, made a little support until J J Thomson™s studies (20 years
study of neutral kaons and discovered the surpris- later) firmly identified them as electrons. Crookes
ing fact that a combination of parity and charge also invented the spinthariscope (1903; Greek for
conjugation was not conserved either. This was an ˜spark-viewer™) to detect the alpha-particles (helium
important result since it was known that a combi- nuclei) emitted by radioactive elements. This con-
nation of parity, charge conjugation and time is sists of a screen coated with ZnS and viewed by a
conserved, implying that the decay of kaons is not lens: each impacting particle causes a visible light
symmetrical with respect to time reversal. flash. Crookes also studied a variety of problems in
Crookes, Sir William (1832“1919) British chemist technical chemistry (sugar from beet; textile
and physicist: discovered thallium; studied ˜cathode dyeing; electrical lighting; antiseptics; sanitation;
rays™; predicted need for new nitrogenous fertilizers. diamond formation) and especially the need to
The eldest of 16 children of a London tailor, little produce fertilizer from atmospheric nitrogen if soil
is known of his childhood. Crookes was a student in fertility was to be maintained (1898). He had much
the Royal College of Chemistry from 1848, and scientific imagination, and he also experimented
became Hofmann™s assistant. After two modest in spiritualism, suggesting that telepathy resulted
teaching jobs he inherited some money, returned from wave communication between brains. His
to London and set up a personal chemical research long, active life covered a most interesting period
laboratory. He was also editor and proprietor of the in science.
Cross, Charles Frederick (1855“1935) British
influential Chemical News from 1859“1906.
In 1861 he examined the spectrum of crude sele- chemist: co-discoverer of viscose process.
nium and found a new bright green line. From this Cross studied chemistry at London, Zürich and
Manchester. With E J Bevan (1856“1921) as partner,
he worked on the chemistry of wood (which con-
sists largely of cellulose and lignin). Their viscose
process (1892) involves extracting cellulose from
wood pulp (or other cheap source) by treating it
with aqueous sodium hydroxide followed by
carbon disulphide. The cellulose solution can then
be squirted through holes into dilute acid to regen-
erate the cellulose as fibre (rayon) or as film
Curie, Marie, n©e Manya Sklodowska (1867“1934)
Polish“French physicist: discovered the radio-
elements polonium and radium.
Manya Sklodowska grew up in Russian-domi-
nated Poland; her family were intensely patriotic
and took part in activities furthering the Polish lan-
guage and culture. Manya™s father was a teacher of
mathematics and physics and her mother the prin-
cipal of a school for girls. She developed an interest
in science, but her parents were poor and there was
no provision for higher scientific education for
women in Poland. She and her sister Bronya, how-
ever, were determined to gain their education.
Manya took a post as a governess and helped Bronya
go to Paris to study medicine, after which she in
turn was to help Manya.
In 1891 Manya went to Paris to study physics. By
Sir William Crookes
Curie, Pierre

nature she was a perfectionist, tenacious and inde- time was spent in supervising the research of
pendent. She graduated in physics in 1893 from the others and raising funds, along with caring for her
Sorbonne, coming first in the order of merit. The two daughters.
following year, with a scholarship from Poland, she In 1910 Marie was proposed for the decoration of
studied mathematics and graduated in second the L©gion d™Honneur, but refused it, as her hus-
place. During this year she met Pierre Curie, then band had refused a previous offer of the honour. At
35 and working on piezoelectricity at the School of the same time she was a candidate for election to
Industrial Physics and Chemistry, and her plans to the Acad©mie des Sciences in Paris (she would have
return to teach in Poland changed; they married in been the first woman member), but was not elected.
July 1895. In 1911 she was awarded a second Nobel Prize for
In 1896 Becquerel had discovered radioactivity chemistry for her discovery of polonium and radium.
in a uranium salt. Marie Curie (as she was now The original unit of measurement of the activity of a
known), looking for a research topic for a doctoral radioactive substance was named the curie (Ci); it is
now defined as a decay rate of exactly 3.7 — 1010 dis-
thesis, decided to study the ˜new phenomena™ dis-
covered by Becquerel. Working in her husband™s integrations per second. Characteristically, she
laboratory, she showed that radioactivity is an insisted on defining the unit herself. In 1914 she orga-
atomic property of uranium and discovered that nized X-ray services for military hospitals; radiogra-
thorium emitted rays similar to uranium. In 1897 phy had hardly begun and there was as yet no
she gave birth to their daughter Irène (who also provision for it. She died at the age of 67 from
became a Nobel Prize winner in physics). When she leukaemia; her exposure to radioactivity is sugges-
examined the natural ores Marie discovered that tive in this.
the radioactivity of pitchblende and chalcolite was Marie Curie was no theoretician, but she was a
more intense than their uranium or thorium con- remarkably skilful radiochemist and her dis-
tent implied, and correctly concluded that they coveries did much to focus research on the new and
must contain new radioactive elements. To find the major field of radioactivity; she was the first
new elements she began to separate the com- woman scientist of international distinction.
Curie, Pierre (1859“1906) French physicist: discov-
ponents of pitchblende to determine where the
radioactivity lay, by a laborious process of frac- ered piezoelectric effect; pioneer in study of
tional crystallization. Pierre Curie left his own radioactivity.
research to join his wife in the work. No precau- The son of a physician, Pierre Curie was educated
tions against radioactivity were taken, as the harm- at the Sorbonne where he became an assistant
ful effects were not then known. Her notebooks teacher in 1878. He was appointed laboratory chief
were subsequently discovered to be highly radioac- at the School of Industrial Physics and Chemistry in
tive and are still too dangerous to handle. 1882 and in 1904 was appointed to a new chair of
In July 1898 they announced the discovery of the physics at the Sorbonne. He and his brother Jacques
existence of an element they named polonium, in (1855“1941) first observed the phenomenon they
honour of Marie™s native country, and in December named piezoelectricity; this occurs when certain
the even more radioactive radium. In order to iso- crystals (eg quartz) are mechanically deformed;
late pure radium they obtained waste ore rich in they develop opposite charges on opposite faces
uranium from mines in Bohemia and, working in and, conversely, when an electric charge is applied
an old shed, they purified and repurified the ore, to a crystal a deformation is produced. If a rapidly
work mostly undertaken by Marie. By 1902 they changing electric potential is applied, the faces of
had obtained one tenth of a gram of radium chlo- the crystal vibrate rapidly. This effect can be used to
ride from several tonnes of ore. It was intensely produce beams of ultrasound. Crystals with piezo-
radioactive, ionizing the surrounding air, decom- electric properties are used in microphones, pick-
posing water, evolving heat and glowing in the ups, pressure gauges and quartz oscillators for
dark. timepieces. Jacques and Pierre Curie used the effect
In 1903 Marie Curie presented her doctoral thesis to construct an electrometer to measure small elec-
(and became the first woman to be awarded such a tric charges; this was later used by his wife in her
degree in France). In 1903 she was awarded the investigation into radioactivity. For his doctorate
Nobel Prize for physics jointly with Pierre Curie (1895), Pierre Curie studied the effect of heat on fer-
and Henri Becquerel for their work on radioactiv- romagnetism and showed that at a certain temper-
ity. The following year their second daughter Eve ature, specific to a substance, it will lose its
was born and the Curies appear to have begun to ferromagnetic properties and become paramag-
suffer from radiation sickness. Pierre Curie was netic; this is now known as the Curie point (eg
named in 1904 as the new professor of physics at 1043 K for iron) He had already shown that mag-
the Sorbonne and Marie was appointed ˜chief of netic susceptibility for diamagnetic materials is
work™ in the laboratory that was to be built for him; generally independent of temperature, but for
it was opened in 1915. In 1906 Pierre was killed in a paramagnetic materials the susceptibility is
street accident and the professorship was offered to inversely proportional to absolute temperature
Marie; she became the first woman professor at the (Curie™s Law).
Sorbonne. She continued to work on radium and He married Manya Sklodowska and thereafter fol-
attempted to isolate polonium, but most of her lowed her into research on radioactivity. Together
Cuvier, Georges, baron

with Becquerel they were awarded the Nobel Prize type of pituitary tumour; it is now known that
for physics in 1903 for this work. Pierre Curie other disorders that increase the production of cor-
showed that 1 g of radium gave out about 500 J h“1, ticosteroid hormones by the adrenal glands also
the first indication of the energy available within lead to this syndrome.
Cuvier, Georges (L©opold Chr©tien Fr©d©ric
the atom and the dangers of radioactivity.
Curtius, Theodor [kurtyus] (1857“1928) German Dagobert), baron [küvyay] (1769“1832) French
organic chemist. zoologist and anatomist: pioneer of comparative
A pupil of Kolbe, he later held professorships at anatomy and vertebrate palaeontology.
Kiel, Bonn and Heidelberg. He first made hydrazine Son of a Swiss soldier, Cuvier was educated in
N2H4 (1887) and hydrogen azide HN3 (1890); and he Stuttgart. He was a brilliant student and from early
studied organic azides and aliphatic diazo com- childhood had been fascinated by natural history.
pounds. All these compounds are toxic or unstable From Stuttgart he went as tutor to a family in
(or both) but have proved of great value in organic Normandy and from 1785 taught in Paris, at the
synthesis. Hydrazine also has industrial uses, and Museum of National History, then the largest sci-
methylhydrazines are used as rocket fuels (eg in the entific establishment in the world.
Apollo probes), with liquid oxygen as oxidant. He did much to establish the modern classifica-
Cushing, Harvey Williams (1869“1939) US physi- tion of animals, extending that of Linnaeus by
ologist and neurosurgeon: pioneered investiga- adding another broader level, the phylum. Thus he
tions of the physiology of the brain. divided the invertebrates into three phyla. His work
A physician™s son, Cushing studied medicine at on molluscs and fish was particularly notable. In
Yale and Harvard, finally specializing in neuro- 1811, working with Brongniart on the Tertiary
surgery. He experimented on the effects of raised rocks of the Paris Basin, he became the first to
intracranial pressure in animals; his improved classify fossil mammals and reptiles, thus founding
methods for diagnosis, localization and surgical vertebrate palaeontology.
removal of intracranial tumours stemmed from Before this, he had developed comparative ana-
this work. For a long time his personal surgical skill tomy and the technique of showing, from a few
in this field was unsurpassed. Measurement of bones, a probable reconstruction of the entire
blood pressure in his patients began in 1906 and animal of an extinct species. His emphasis was
knowledge of hypertension and its effects begins always on the facts and he derided general theories.
with his work. From 1908 he also studied the func- In long conflicts with Lamarck and E Geoffroy St-
tion and pathology of the pituitary gland at the Hilaire (1772“1844) (both precursors of Darwin) he
base of the brain, again working first with dogs. He attacked theories of evolution: he believed in cata-
showed that acromegaly is linked with one type of strophes, with the Biblical flood as the most recent.
pituitary overactivity in the growing animal and After each catastrophe, life was created anew.
dwarfism with its underactivity. Cushing™s syn- Cuvier became the world™s most eminent biologist
drome, which is associated with chronic wasting in his lifetime, with an authority akin to that of
and other symptoms, he showed to be linked with a Berzelius in chemistry.

Daguerre, Louis Jacques Mand© [dagair] (1787“ Further, by 1837 he found that the result could be
1851) French inventor of the daguerrotype. ˜fixed™, ie rendered permanent, by washing with
No other invention in the 19th-c produced as common salt in water. Confidently, Daguerre
much popular excitement as photography, for sought publicity, and used his experience as an
which the first practical process was devised by entrepreneur to seek public and governmental sup-
Daguerre. He was trained as a scene painter and port. He named the scheme ˜the daguerrotype
stage designer at the Paris opera and in 1822 he process™ (although the profits were shared equally
devised the Diorama: this was an entertainment with Ni©pce) and succeeded, through the efforts of
based on large (12 — 20 m) semi-transparent Arago, in attracting government praise and
painted linen screens, which were hung and inge- finance. Grandly, the French government offered
niously lit to create illusions of depth and move- his invention freely to the world on 19 August 1839,
ment. This strange precursor of the cinema was a although Daguerre had patented his scheme in
great popular success and ˜Diorama Theatres™ London 5 days before this. Public interest was
opened in Paris, London and other capital cities. intense, even though the invention of the new art
Daguerre used a camera obscura (a box with a lens was widely held to be blasphemous.
at one end and a small screen at the other end) to ˜From today painting is dead™ said the artist
assist him in making his design sketches and he Delaroche. It was claimed that by 1839 ˜all Paris was
soon began experiments to mechanize or capture seized with daguerrotypomania™. Cartoons showed
the image and so avoid the laborious tracing. engravers hanging themselves. The invention was
In 1826 he met Ni©pce, who was working on sim- claimed to be ˜a mirror with a memory™ and ˜the
ilar lines, and in 1830 they formally became part- first to conquer the world with lightning rapidity™,
ners. In 1831 after extensive experiments based on despite its defects. These were many: the equip-
the known sensitivity of some silver compounds to ment was bulky and exposures took many minutes
light, he began to use a silvered copper plate in strong sunlight. The resulting daguerrotype was
iodized by exposure to iodine vapour as the light- difficult to see; it was laterally reversed; and the
sensitive surface. This was Ni©pce™s idea; and then plate could not be replicated. But despite being a
in 1835 Daguerre made by chance a momentous photographic dead-end in a technical sense, it ini-
discovery. A plate which had been exposed in a tiated a technique of visual recording using silver
camera obscura without any visible result was left which through the efforts of Archer, Talbot and
in a cupboard; a few days later it was found to bear others has progressed ever since. Daguerre™s
a visible picture. Amazed, he soon found that this instruction manual appeared in 32 editions in
result was due to a latent image being ˜developed™ eight languages in 1839 and he retired in 1840
by mercury vapour from a broken thermometer. in honour and some glory to a modest estate at
This trick of ˜development™ allowed a picture to be Bry-sur-Marne.
Dale, Sir Henry Hallett (1875“1968) British physi-
made after a photographic exposure time as short
as 20 minutes. ologist and pharmacologist: worked on histamine
and on acetylcholine.
Educated in medicine in Cambridge, London and
Frankfurt, Dale joined the Wellcome Laboratories
in 1904 and at once began (at the suggestion of Sir
H Wellcome (1853“1936)) to study the physiological
action of ergot (a potent extract from a fungal infec-
tion of rye) on test animals. This work led, through
fortunate and shrewd observations and the skill of
his co-worker G Barger (1878“1939), to the two
research themes especially linked with their
names. These are, firstly, the work on histamine, a
compound released by injured cells or in reaction
to foreign protein, and secondly the work on the
neurotransmitter acetylcholine. Both these areas
have been fruitful for extended investigations,
leading to fuller understanding of allergy and ana-
phylactic shock, and the nature of chemical trans-
mission of nerve impulses. Dale directed the
Medical Research Council from 1928“42; in 1936 he
shared a Nobel Prize with Otto Loewi (1873“1961).
L J M Daguerre, from a daguerrotype of 1848.
Dart, Raymond Arthur

lists were on the scale H = 1, but now a scale on
For many years he was a dominant spokesman for
which the common isotope of carbon = 12 is used.
science in the UK, especially in the medical and
allied sciences. After Avogadro™s work, corrections were needed
d™Alembert, Jean Le Rond see Alembert (eg water is H2O, not HO) and discussion by
Dalton, John (1766“1844) British meteorologist and chemists on these changes, and improved analyses,
chemical theorist: proposed an atomic theory greatly occupied 19th-c chemists. The unit of rela-
linked to quantitative chemistry. tive atomic mass is named the dalton for him. The
Dalton was the son of a weaver and a Quaker and dalton is equal to one-twelfth of the mass of a neu-
grew up in an isolated village in Cumbria. He left his tral carbon-12 atom.
village when he was 15 for Kendal in central Dalton himself remains a strangely dull perso-
Cumbria and thereafter made his living as a nality. His main work came after he was 30. He was
teacher. In 1793 he moved to Manchester and a gruff lecturer, a poor experimenter and his writing
taught science, and from 1799 he worked as a pri- seems old-fashioned. Apart from the brilliant
vate tutor, giving short courses to groups of stu- insight of his atomic theory, his other work seems
dents for a modest fee. Throughout his life, from pedestrian. He was independent, modest and attrib-
1781, he kept daily meteorological records. This uted his success to ˜perseverance™.
interest in weather and the atmosphere led to his Manchester was strongly aware of Dalton™s fame.
work on gaseous mixtures generally. His lying in state in their Town Hall was attended
In 1794 he wrote an excellent paper on colour by 40 000 people, his funeral was a major public
vision (he was colour blind); in 1799, returning to event and memorials (sculptural and financial)
his interest in the weather, he showed that springs were made, marking the surprising regard in an
arise from stored rainfall. This concern with rain industrial city at that time for a scientific theorist.
and the water content of the atmosphere, which He had instructed that his eyes be studied to find
appears as the origin of all his work on gases and on the cause of his colour blindness. This was done 150
atomic theory, arose through his life in the wet years after his death, and DNA from them was
Lake District and the influence of a childhood found to lack the genes giving the green-sensitive
teacher. He made his reputation in science in 1801 pigment present in the normal human eye.
Dam, (Carl Peter) Henrik (1895“1976) Danish bio-
with his Law of Partial Pressures. This states that
the pressure of a gas mixture is the sum of the pres- chemist, discoverer of vitamin K.
sures that each gas would exert if it were present Dam studied in Copenhagen and later in Freiburg
alone and occupied the same volume as the whole and Zürich before being appointed Assistant
mixture. He also found the law of thermal expan- Professor of Biochemistry in Copenhagen in 1928.
sion of gases, now known as Charles™s Law Soon after this he was studying the effect of a
although Dalton published it first. In 1803, at the restricted diet on chicks, and found that within 2“
end of a paper on gas solubility, he noted rather 3 weeks they got haemorrhages under the skin and
casually his first table of relative atomic masses. their blood showed delayed coagulation. They were
The interest this aroused led him to develop his not cured by feeding the then-known vitamins, but
theory further, in lectures and in his book A New by 1934 he found that hempseed, tomatoes, green
System of Chemical Philosophy (1808). Briefly, his leaves and hog liver contained something that pre-
atomic theory proposed that every element con- vented the bleeding and by 1935 it was recognized
sists of very small particles called atoms, which are as a new vitamin, ˜K™. Later Doisy showed it to con-
indivisible and indestructible spheres. The atoms sist of two closely related compounds, K1 and K2,
of one element were presumed to be identical in all and Dam and others showed that its deficiency
respects, including mass, but to differ from atoms leads to lack of prothrombin, which is needed in
of other elements in their mass. Chemical com- the series of changes involved in blood coagulation.
pounds are formed by the union of atoms of differ- Dam and Doisy shared the Nobel Prize for physiol-
ent elements, in simple ratios (ie elements A and B ogy or medicine in 1943.
Daniell, John Frederic (1790“1845) British meteo-
would form a compound AB; and possibly A2B, AB2,
A2B3). This is known as the Law of Simple Multiple rologist and chemist: devised Daniell cell.
Proportions. Although his early research was in meteorology
The theory was able to interpret the laws of chem- (he devised a dew-point hygrometer and theorized
ical combination and the conservation of mass; it on the atmosphere and trade winds), Daniell is best
gave a new basis for all quantitative chemistry. known for his work on primary cells. The earliest
Each aspect of Dalton™s theory has since been types quickly lost power. The Daniell cell (1836)
amended or refined, but its overall picture remains uses amalgamated zinc as negative electrode and
as the central basis of modern chemistry and copper as positive electrode, and gives a nearly con-
stant emf of ≈ 1.08 V. It proved a great asset in teleg-
Dalton assumed that when only one compound raphy and in the study of electrolysis. In 1831
of two elements exists (for example water was the Daniell became the first professor of chemistry at
only compound of hydrogen and oxygen then King™s College, London. (Portrait on p. 118)
Dart, Raymond Arthur (1893“1988) Australian
known) it had the simplest formula; ie HO for
water. On this basis, relative atomic masses anatomist and palaeoanthropologist: discovered
(˜atomic weights™) could easily be found; the early Australopithecus africanus.
Darwin, Charles

After qualifying as a physician from the Uni- doubts, so did FitzRoy. Darwin™s voyage on the
versity of Sydney in 1917, Dart served in France Beagle began in 1831, and was to last 5 years and to
before being appointed professor of anatomy at the stir a revolution in biology.
newly formed University of the Witwatersrand, At that time, biologists in general believed either
Johannesburg, in 1922. The work there he found to that species in natural conditions had continued
be a most depressing experience, until in 1924 one without change since their original creation, or
of his students showed him a fossil baboon skull else (like Lamarck) they thought that a characteris-
that had been found in a lime quarry at Taung, tic acquired in life could simply be inherited by the
Botswana. Dart arranged with the quarry managers offspring. Darwin™s experience on his voyage made
for any other similar items to be preserved and sent him doubtful of both theories. For example, he
to him, and soon afterwards the skull of a hitherto studied the life of the Galápagos Islands, off the
unknown hominid, named by Dart Australopithecus western coast of South America. These 10 rocky
africanus (˜southern ape of Africa™), was discovered. islands are typically about 80 km apart, with a sim-
Dart™s claim that Australopithecus was the ˜missing ilar climate, and are separated by deep and fast sea.
link™ between man and the apes was rejected by They are free from gales, and their geology suggests
authorities of the day, however, until Broom found they were never united and are geologically quite
further hominid remains in the Transvaal in 1936. young. The few plants and animals resemble those
It is now thought that Australopithecus lived about in South America, but are different. Remarkably,
1.2“2.5 million years ago but it is still a matter of each island has to a large extent its own set of
debate whether modern man is directly descended plants and animals; there are tortoises, finches,
from him or if he only represents an unsuccessful thrushes and many plants which correspond in sev-
evolutionary branch from a much earlier common eral islands but are detectably different, so that as
ancestor. the vice-governor Lawson told Darwin, speaking of
Darwin, Charles (Robert) (1809“82) British natu- tortoises, ˜he could with certainty tell from which
ralist: developed a general theory of evolution and island any one was brought™. (Incidentally, these
natural selection of species. animals can live over 170 years; some now living
Young Darwin must have been a disappointment may have seen Darwin and the Beagle.)
to his talented family. His 7 years at Shrewsbury Darwin published the Journal of his voyage in
School in his home town led to no career choice and 1839, and from then on he gathered his notes on
his 2 years at Edinburgh as a medical student he species and read extensively. He read T R Malthus™s
found ˜intolerably dull™. His father, a successful (1766“1834) ideas of 1798 on human populations
physician, tried again and sent him to Cambridge and their survival in the contest for food, and
to study for the church but, although he made Darwin concluded that all plant and animal species
some good friends, his 3 years were ˜sadly wasted undergo variation with time and that some varia-
there™ and his main interests were still insect- tions tend to be preserved and others destroyed as
collecting and bird-shooting. Then, when he was a result of the inexorable contest for survival
22, he learned that Captain Robert FitzRoy (1805“ among all living things. Darwin™s collection of
65) had been commissioned by the Admiralty to material on this subject was made while he lived as
take the naval survey ship HMS Beagle on a scientific a country gentleman in Kent, with his wife Emma
expedition to circumnavigate the southern hemi- Wedgwood (his first cousin) and their 10 children.
sphere and was looking for an unpaid volunteer He discussed his views with his two close friends,
naturalist to join him. Darwin was attracted; his the geologist Lyell and the botanist Hooker, but he
father was against it, but his uncle Josiah was in no hurry to publish them.
Wedgwood (1769“1843) approved and, after some Then in 1858 he had a shock; Wallace, then in
Malaya, sent him an essay offering the same essen-
tial idea and inviting his opinion. As a result, he
and Wallace published at the same time in 1858 by
agreement. The next year Darwin™s book The Origin
of Species by Means of Natural Selection appeared,
giving his ideas in detail; it created excitement
among biologists and widespread discussion. Many
churchmen were shocked by it, since Darwin™s
theory of evolution entailed no special need for
divine intervention and the theory implied also
that man had evolved like other organisms and was
not a product of a Biblical creation.
Darwin was diffident (and manipulative), and the
forceful arguments for his ideas were pressed by his
friends, especially T H Huxley. Interestingly,
Darwin had no understanding of mutation, or of
heredity in the modern sense and, although
Mendel™s work on heredity appeared in 1865, it
was neglected then and effectively rediscovered
Charles Darwin, aged 40.
Davis, William Morris

G.e. darwini G.e. abingdoni


G.e. chathamensis G.e. microphyes

G.e. elephantopus G.e. hoodensis

Galápagos giant tortoise, showing shell shape of subspecies

only in 1900. The modern development of much of Darwin (1731“1802) was a physician, biologist,
biology, anthropology and palaeontology is based engineer and poet, and the presiding genius of the
on the idea of evolution of species, while discussion Lunar Society; he had ideas on evolution that were
still continues on aspects of the subject such as ahead of their time. Erasmus™s second wife was the
whether the rate of evolutionary change is broadly grandmother of Galton, who examined the statis-
uniform or includes periods of both sluggish and tics of inherited talent, in his own and other fami-
rapid change. lies (see family tree, p. 135).
Dausset, Jean [dohsay] (1916“ ) French immunol-
Darwin was a very careful observer and his theo-
rizing showed both independence of mind and a ogist: made important investigations into blood
desire (combined with caution) to reach general transfusion reactions.
theories in biology. His famous work is in his best- From the time during the Second World War
selling books, The Voyage of the Beagle and The Origin when he served in a blood transfusion unit, Dausset
of Species (their short titles), but he also wrote on the was mainly interested in transfusion reactions.
evolution of man, on emotion in men and animals This led him in the early 1950s to discover that the
and on climbing and insectivorous plants; he belief that blood of group O can be used for all
worked hard despite recurrent illnesses. He had patients is false. If the donor has recently been
ideas on the origin of life and in a letter of 1871 to given antidiphtheria or antitetanus vaccine, the
Hooker wrote that ˜if (and oh what a big if) we could resulting antibodies can produce shock reactions
conceive in some warm little pond, with all sorts of when the blood is transfused. Continuing his study
ammonia and phosphoric salts, light, heat, elec- of transfusion responses, Dausset found that
tricity, etc, present, that a protein compound was patients who had many blood transfusions were
chemically formed™ but he recognized that such prone to produce antibodies against the white cells.
speculation was then premature. In fact, ideas a The antigen (human lymphocyte antigen, HLA) is,
century later were broadly in accord with his. he suggested, related to the mouse H-2 system. The
Darwin also contributed to geology, but his valu- work led to ˜tissue typing™ by simple tests and
able work on coral atolls and on land elevation has proved of great value in reducing rejection risks in
been overshadowed by his massive contribution to organ transplant surgery. Dausset shared a Nobel
biology. Prince Albert and Lord Palmerston in 1860 Prize in 1980 with G D Snell (1903“96) and
proposed to Queen Victoria that Darwin be Venezuelan-born B Benacerrof (1920“ ), both US
knighted, but Wilberforce (Bishop of Oxford) per- medical graduates whose work in immunological
suaded the queen against this, and he was never genetics was mutually complementary.
Davis, William Morris (1850“1934) US physical
honoured by the Crown. He was buried in
Westminster Abbey, near Newton. geographer: pioneer of geomorphology.
Other members of Darwin™s family contributed After a period as a meteorologist in Argentina,
to work on evolution. His grandfather Erasmus Davis worked with the North Pacific Survey before
Davisson, Clinton Joseph

Davy, Sir Humphry (1778“1829) British chemist:
being appointed to a post at Harvard in 1877. He
pioneered the study of landforms, conducting a discoverer of sodium and potassium, exploiter of
classic study of the drainage system of the electrochemistry and propagandist for science.
Pennsylvania and New Jersey area in 1889 in which Son of a Cornish woodcarver and small farmer,
he illustrated his idea of erosion cycles. He pro- Davy became an apprentice pharmacist. However,
posed that the erosive action of rivers causes first in 1798 he was employed by Beddoes to work in his
the cutting of steep V-shaped valleys, which mature Medical Pneumatic Institution in Bristol with the
into broader valleys and lead eventually to the for- task of developing the medical uses of some newly
mation of a rolling lowland landscape that he discovered gases. Davy made N2O (˜nitrous oxide™ or
termed a ˜peneplain™. ˜laughing gas™) in quantity, studied it fully and,
Davisson, Clinton Joseph (1881“1958) US physi- through this work and some useful friendships,
cist: discovered experimentally the diffraction of was appointed as chemist by Rumford in the new
electrons by crystals. Royal Institution in London, in 1801. He quickly
After graduating from the University of Chicago became famous as a lecturer. His ideas on the uses
and taking his PhD at Princeton, Davisson worked of science appealed to the serious-minded, and
at the Carnegie Institute of Technology (1911“17). demonstrations (especially of the inhibition-releas-
He then joined the Bell Telephone Laboratory (then ing effects of N2O) attracted others. Davy made the
the Western Electric Co Laboratory) for wartime Royal Institution a social and financial success and
employment after being refused enlistment in thereby acquired the equipment (especially a large
1917, and subsequently stayed until his retirement voltaic cell) to develop his interest in electrochem-
in 1945. istry. In 1807 he made the reactive metals potas-
The Davisson and Germer experiment, which sium and sodium by electrolysis; and soon he
confirmed Broglie™s hypothesis that particles secured other new and reactive metals. These excit-
could behave like waves (and thus fundamentally ing discoveries were followed by experiments that
altered modern physics), was initially accidental showed that chlorine was probably an element (and
and in part due to a patent suit. Western Electric not a compound); and further work related it to
were protecting their patent for De Forest™s three- iodine, newly found by B Courtois (1777“1838), and
element vacuum tube (with an oxide-coated fila- to fluorine.
ment) against Langmuir™s similar tube with a In 1812 he was knighted, and 3 days later married
tungsten filament developed by him at General Jane Apreece, a wealthy Scottish widow. He was
Electric Co. In order to help settle the suit (which now established as Britain™s leading scientist and
dragged on for a decade), Davisson and Germer he embarked on the first of many European tours.
measured electron emission from oxide-coated In 1813 he hired Faraday as an assistant (and also
platinum under ion bombardment. The purpose tried to use him as a valet on his travels). In 1815 he
was to establish that the electron emission did not was asked to devise a safe lamp for use in gassy
depend upon positive ion bombardment due to coalmines. This was the sort of problem that
oxygen traces in the tube, and therefore that showed his talent well. In 6 months he had made
Langmuir™s tube did not fundamentally differ from the first thorough study of flame combustion and
that already under patent. This they did, and the devised his safety lamp, which made mining of
Supreme Court eventually ruled in Western deep coal seams possible even where firedamp
Electric™s favour. In the meantime Davisson and C H (CH4) was present. The engineer George Stephenson
Kunsman investigated electron emission under
electron bombardment as an easy extension to the
work, and found a small number of primary elec-
trons with the full energy of the incident beam
deflected back alongside the many low energy sec-
ondary electrons. In 1925 an accidental explosion
of a liquid-air bottle heavily oxidized a nickel sur-
face which Davisson was investigating, and after
heating to clean it (which also recrystallized it from
polycrystalline into a few large crystals) it displayed
a maximum scattering at a particular angle.
On visiting Oxford in 1926 and hearing of
Broglie™s recent work, postulating wave behaviour
for an electron, Davisson realized that he had seen
diffraction maxima in the electron wave pattern. In
1927 Davisson, with Germer, obtained conclusive
evidence that electron beams were diffracted on
reflection by nickel crystals and had the wave-
length predicted by Broglie. For this he shared the
1937 Nobel prize for physics with G P Thomson,
who had observed similar electron diffraction with
high-energy electrons passing through metal foil. Humphry Davy
Dedekind, Julius Wilhelm Richard

(1781“1848) invented a similar safety lamp at about derm). In 1940 he also refuted E Haeckel™s (1834“
the same time, and both later claimed priority. 1919) theory of phylogenetic recapitulation;
Davy™s reputation outstrips his chemical achieve- according to this theory an organism in its embry-
ments, substantial though they were. He had great onic stage repeats the adult stages of the organ-
energy and talent, especially in attacking limited ism™s evolutionary ancestors. De Beer showed that
but important chemical problems. He was also in fact the situation is rather the converse; adult
snobbish, excitable and ungenerous to other scien- animals retain some juvenile features of their
tists, unskilled in quantitative work and uneven in ancestors (paedomorphism). His many other
his knowledge or interest in theories (he doubted researches included studies of the earliest known
Dalton™s new atomic theory). His early death left bird, Archaeopteryx, and led him to propose a pat-
˜brilliant fragments™ (said Berzelius), much inter- tern of ˜piecemeal™ evolution to explain its posses-
est in electrochemistry and perhaps his finest ˜dis- sion of both reptilian and avian features (eg teeth
covery™, Faraday. An important achievement was and wings); he worked on the origin of the
that he had sold science to the industrialists, espe- Etruscans from blood group data and on
cially through his success with the miner™s safety Hannibal™s route over the Alps.
de Broglie, Louis Victor Pierre Raymond, duc
lamp. His suggestion in 1800 that, as inhaling
de, see Broglie
nitrous oxide ˜appears capable of destroying physi-
de Buffon, Georges-Louis Leclerc, comte
cal pain™, it could be useful as an anaesthetic in
(Count) see Buffon
surgery was not taken up for another half-century.
Debye, Peter (Joseph William) [duhbiy] (1884“
It is still much used for this.
He had an intense interest in angling; his youn- 1966) Dutch“US chemical physicist; developed
ger brother John (also a chemist) says he was ˜a little ideas on dipole moments, and on solutions of elec-
mad about it™. He was an enthusiastic poet and trolytes.
had friends with real literary talent, including Debye was educated in the Netherlands and in
Coleridge, Southey and Wordsworth, who thought Germany, and then held posts in theoretical
better of his poetry than do modern critics. physics in several European countries in rapid suc-
de Bary, (Heinrich) Anton [duh baree] (1831“88) cession. Despite these frequent moves, he produced
German botanist: a founder of mycology. in 1911“16 a theory of the change in specific heat
De Bary left medicine to teach botany in three capacity with temperature, a method for X-ray dif-
German universities before settling in Strasbourg fraction analysis using powdered crystals (with P
in 1872. His main work was in mycology, where he Sherrer) and the idea of permanent molecular elec-
showed that fungi are the cause of rust and smut tric dipole moments. He showed how these
diseases of plants (and not a result, as others had moments can be measured and how they can be
thought). He went on to show that lichens consist used to find the shape of simple molecules; eg the
of a fungus and an alga in intimate partnership, molecule of water, H“O“H, is not linear but bent.
forming a remarkably hardy union with mutual He was also able to show that the benzene ring is
benefits. De Bary named this symbiosis; the term flat. The unit of electric dipole moment, the debye
(D), is the electronic charge (e) — 10“10 m. His work
now is used to cover three kinds of specialized asso-
ciation between individuals of different species, with Hückel led in 1923 to the Debye“Hückel
including parasitism (one organism gains, the theory of electrolytes, which deals with the behav-
other loses) as well as commensalism (one organ- iour of strong solutions of electrolytes by taking
ism gains, the other neither loses nor gains) and account of the mutual interaction of the charged
mutualism (a mutually beneficial association, as in ions (previous theories had dealt only with very
the lichens). dilute solutions). In 1934 he moved to Berlin and in
De Bary™s excellent descriptions and classifica- 1940 to the USA, where he was professor of chem-
tions of fungi, algae, ˜moulds and yeasts™, estab- istry at Cornell until 1950. His work on light scat-
lished them as plants that happen to be small and tering in solutions, on polymers and on magnetism
did much to create modern mycology. is also important. He was awarded the Nobel Prize
de Beer, Sir Gavin Rylands [duh beer] (1899“1972) for chemistry in 1936, and in 1939 had the strange
British zoologist: refuted germ-layer theory in experience of seeing a bust of himself unveiled in
embryology, and theory of phylogenetic recapitula- his native city of Maastricht.
de Candolle, Augustin-Pyramus see Candolle
du Chatelet-Lomont, Gabrielle-Emilie, mar-
De Beer served in both world wars, in Normandy
quise (Marchioness) see Chatelet-Lomont
in 1944 with the Grenadier Guards as a Lieutenant-
de Coriolis, Gaspard Gustave see Coriolis
Colonel; in the interval he graduated from Oxford
de Coulomb, Charles (Augustin) see Coulomb
and he afterwards taught there. After the Second
Dedekind, Julius Wilhelm Richard [dayduhkint]
World War he became professor of embryology in
London and from 1950 director of the British (1831“1916) German mathematician: made far-
Museum (Natural History) until he retired in 1960. reaching contributions to number theory.
In 1926 he much injured the germ-layer theory in Dedekind studied at Brunswick and then formed
embryology by showing that some bone cells a close association with Riemann, Dirichlet and
develop from the outer (ectodermal) layer of the Gauss at Göttingen, with each influencing the
embryo (the theory had them form from the meso- others. Dedekind learned about the method of least
de Duve, Christian

squares from Gauss, the theory of numbers, poten- widely, having given up an army career and
tial theory and partial differential equations from devoted himself to geology. He mapped and wrote
Dirichlet. After a short time he moved briefly to the first descriptions of the Jurassic and Cretaceous
Zürich, and then returned to spend the rest of his rocks of the Devon and Dorset area, the geology of
long life as a professor at the Technical High the Pembrokeshire coast and that of Jamaica.
School, Brunswick. He lived long enough for much During the late 1820s he began his most significant
of his influential work (eg on irrational numbers) work, the first systematic geological survey of
to become familiar to a generation of students in Britain. Working at first as an amateur, his efforts
his later years, and he became a legend. Some 12 led to the establishment of the Geological Survey
years too soon, Teubner™s Calendar for Mathema- of Great Britain in 1835, with himself as its first
ticians recorded him as having died on 4 September director.
de Laplace, Pierre Simon, marquis see Laplace
1899. Much amused, Dedekind wrote to the editor:
de la Tour, Charles Cagniard see Cagniard de la
˜According to my own memorandum I passed this
day in perfect health and enjoyed a very stimulat-
Delbrück, Max [delbrük](1906“81) German“US bio-
ing conversation ... with my ... friend Georg Cantor
of Halle™. physicist: pioneer of molecular biology.
Dedekind was one of the first to recognize the Delbrück is unusual in 20th-c science for practis-
value of the work of Cantor (1845“1918) on infinite ing both physics and biology and for the fact that
qualities. Dedekind himself made major steps his place, although substantial as a discoverer, is
towards modern standards of rigour and was ahead largely that of an inspirer of others in the creation
of his time in his approach to number theory. of molecular biology.
In 1858 he produced an arithmetic definition of He began in physics, with a PhD from Göttingen
continuity and clarified the concept of an irra- in 1930, and spent 2 years on atomic physics with
tional number (that is, roughly, a number that Bohr, then 5 years as assistant to Lise Meitner at
cannot be represented as a fraction). In the first the Kaiser Wilhelm Institute in Berlin; and from
of three books he used Dedekind cuts (the categ- 1937 he was at the California Institute of
orization of irrational numbers by fractions) to Technology, where he moved into biology. Morgan
rigorously examine the real number system. and the ˜Drosophila™ geneticists had gone to
Then in his second major work (1888) he estab- Pasadena from New York in 1928, taking with them
lished a logical foundation for arithmetic and the conviction that genetic problems should be
described axioms that exactly represent the logical solvable by chemistry and physics. Delbrück
concept of whole numbers (these are now, incor- agreed, with the proviso that new concepts in these
rectly, called Peano axioms). Finally, Dedekind sciences would be needed, and his ideas were devel-
described in 1897“1900 the factorization of real oped in the physicist Schrödinger™s influential
numbers using modern algebra. book What is Life? in 1945. Delbrück decided to work
de Duve, Christian (Ren©) see Duve on viruses as the simplest life form. He did much to
de Fermat, Pierre see Fermat create bacterial and bacteriophage genetics, and in
De Forest, Lee (1873“1961) US physicist: inventor of 1946 he showed that viruses can exchange (recom-
the thermionic triode ˜valve™ (electron tube) and bine) genetic material, the first evidence of recom-
pioneer of radio. bination in primitive organisms. His firm belief in
De Forest studied at Yale University, writing his an ˜informational basis™ in molecular biology bore
doctoral thesis on radio waves (probably the first fruit in other hands, but with much help from his
thesis on the subject of radio in America). He went forceful catalytic ideas. He shared a Nobel Prize in
to work for the Western Electric Company and in 1969, which led to another of his famous parties.
Democritus (of Abdera) [demokrituhs] (c.470“
1907 developed and patented the thermionic
triode. This device, essentially a diode with an addi- c.400 bc) Greek philosopher: pioneer of atomic
tional electrode between cathode and anode, could theory.
be used to amplify weak electrical signals and was Almost nothing is firmly known of Democritus™s
crucial to the development of radio communica- life, and his ideas have survived through the writ-
tion, radar, television and computers. The triode ings of others, either supporting or attacking him.
remained an essential component in all kinds of His idea of atoms seems to have begun with his
equipment for 50 years before being largely super- teacher Leucippus (5th-c bc), but Democritus much
seded by the transistor. De Forest also worked on a extended the theory. He proposed that the universe
film soundtrack system and a medical diathermy contains only a vacuum and atoms, and that these
machine, the former being a commercial failure at atoms are invisibly small and hard, eternal and are
the time but later widely adopted. in ceaseless motion. On this adaptable, materialist
de la Beche, Sir Henry Thomas [beech] (1796“ view he explained taste, smell, sound, fire and
1855) British geologist: conducted first systematic death. He supposed that in their form and behav-
geological survey of the British Isles. iour lay the natural, godless cause of all things and
After the early death of his father, de la Beche all events. Plato and Aristotle were not in favour of
lived with his mother for a time in the fossil-rich these ideas, which never formed a part of the main-
area of Lyme Regis in Dorset. He entered military stream of Greek philosophy, but they were adopted
training school at the age of 14 and later travelled by the Greek philosopher Epicurus about 300 bc
Deville, Henri Étienne Sainte-Claire

and well recorded in a long poem (On the Nature of
Things) by the Roman Lucretius (c.99“55 bc). In the
17th-c Boyle and Newton were aware of these
ideas; it is doubtful if they contributed at all
directly to modern atomic theory, which began
with Dalton about 1800.
de Moivre, Abraham [duh mwahvruh] (1667“
1754) French“British mathematician: founded
analytical trigonometry and stated de Moivre™s
De Moivre had the misfortune to be a Huguenot
(Protestant) at the time that Roman Catholic France
revoked the Edict of Nantes and began to persecute
them (1685). He was imprisoned in Paris for a year
and moved to England on his release. Friendship
with Newton and Halley aided his election to the
Royal Society (1697). However, de Moivre remained
poor, working as a tutor or consultant to gambling
or insurance syndicates, and never obtained a uni-
versity post. He died blind and disillusioned, with
his work unrecognized.
Ren© Descartes
His book The Doctrine of Chances (1718) is a master-
piece, and sets out the binomial probability or
Gaussian distribution, the concept of statistical braic methods can be applied to their solution; con-
independence and the use of analytical techniques versely he applied (for the first time) geometry to
in probability. Deriving an expansion for algebra. His methods made a massive change in
n! = n (n “ 1) (n “ 2) ...3.2.1, de Moivre summed mathematical thought and remain familiar today,
terms of the binomial form. He established many of as in the equation of the straight line, y = mx + c and
the elements of actuarial calculations. Above all he the equations of familiar curves such as the conic
discovered the trigonometric relation sections. The thinker J S Mill (1806“73) claimed that
(cos θ + i sin θ)n = cos nθ + i sin nθ Cartesian geometry ˜constitutes the greatest single
called de Moivre™s theorem (1722), which is a step ever made in the progress of the exact sciences™.
powerful step in developing complex number Although Descartes™s ideas on the nature of con-
theory. sciousness were valuable, they have been overtaken
de Montgolfier, Joseph(-Michel) and by modern work. Curiously, despite being fond of
(Jacques-)Étienne see Montgolfier his pet dog, since he believed that animals have no
de R©aumur, Ren©-Antoine Ferchault see rational soul it followed that they lacked con-
R©aumur sciousness or feelings of any kind.
Descartes, Ren© [daykah(r)t] (1596“1650) French de Sitter, Willem see Sitter
Desmarest, Nicolas [daymaray] (1725“1815) French
philosopher and mathematician: creator of analyt-
ical geometry. geologist: demonstrated the igneous origin of
Descartes has a dominant position in shaping basalts.
modern philosophy, but this is not our concern Desmarest was by profession a trade and industry
here. With enough modest inherited wealth to live inspector for the department of commerce. In the
as he chose, he spent his life in travel, on his work 1760s he became interested in the large basalt
in philosophy, mathematics, physics and physiol- deposits of central France (discovered by Guettard
ogy and as a soldier serving in Holland, Bohemia a decade before) and succeeded in tracing their ori-
and Hungary. In 1621 he left the army and in 1629 gins to ancient volcanic activity in the Auvergne
settled in Holland for some 20 years, before being region. In 1768 he produced a detailed study of the
persuaded to become tutor to Queen Christina of geology and eruption history of the volcanoes
Sweden, a headstrong and athletic 19-year-old. responsible. His work was important because it
From childhood Descartes had risen late and demonstrated that basalts were igneous in origin,
claimed to do his best thinking in a warm bed; the which led to the abandonment of the widely held
Queen™s insistence on tutorials in philosophy at belief that all rocks were sedimentary (the Neptunist
5 am in a freezing library either hastened or pro- theory of A G Werner).
Deville, Henri Étienne Sainte-Claire (1818“81)
duced the lung disease which killed him within 5
months of arrival. French chemist: developed methods for making
Although Descartes theorized extensively in light metals in quantity; studied high temperature
physics and physiology, his lasting influence out- reactions.
side philosophy is in mathematics, where he cre- Deville is one of the few major 19th-c scientists to
ated analytical or coordinate geometry, also named be born in the West Indies, where his family had
(after him) Cartesian geometry. This translates geo- been leading citizens for two centuries. With his
metrical problems into algebraic form, so that alge- older brother Charles he was educated in Paris. He
de Vries, Hugo

chose medicine but was soon attracted to chem- to the Professorship of Chemistry at the Royal
istry; in the 1840s he worked on essential oils and Institution, London. Thereafter he lived and
obtained methylbenzene and methyl benzoate worked in London, visiting Cambridge only briefly
from balsam of Tolu, but his chemical fame began and infrequently in order to abuse his staff there
in 1849 when he made the crystalline and highly for idleness and to visit G D Liveing (1827“1924),
reactive dinitrogen pentoxide by treating warm professor of chemistry; they collaborated in spec-
silver nitrate with chlorine. From 1851 he held a troscopic research for 25 years. Dewar had a
post at the École Normal Sup©rieure, with Pasteur strangely wide range of research interests, which
as a colleague and close friend from 1857. The main he maintained with his own hands or with assis-
work of the institution was to train senior school tants, never having students or founding a ˜school™.
teachers, which Deville did for 30 years while main- In the early 1870s he invented the Dewar flask
taining a major research output. He was a masterly (domestically a Thermos flask), a double-walled
lecturer and experimentalist, uninvolved in dis- glass flask with the inner walls reflective and the
putes over theory. Realizing that sodium metal in space between them evacuated; heat is only slowly
quantity would be of great use, he developed a passed to or from the contents. From 1877 he
large-scale method for making it by reduction of worked on the liquefaction of gases, using the
sodium carbonate with carbon. One target was to flasks for storage. He used Cailletet™s method for
use sodium to make aluminium by reduction of making oxygen, on a scale which allowed him to
AlCl3. In 1855 Deville was summoned to show alu- study low temperatures; and by 1898 he made
minium, then rare, to the Emperor; the latter was liquid hydrogen in quantity and the solid in l899, at
attracted by the idea of fitting his troops with hel- a temperature below 14 K. At this temperature all
mets of the new metal, and a government grant to known substances become solid, except helium. He
set up a pilot plant was arranged. Success followed; tried to liquefy helium, discovered on Earth in 1895,
bars of aluminium were shown at the 1855 but did not succeed. With F A Abel he invented
Exposition, and it quickly ceased to be mainly used cordite. He worked on specific heat capacities, elec-
for jewellery. Soon Deville made pure magnesium trical effects of very low temperatures, metal car-
in quantity, and titanium, and crystalline boron bonyls, diffusion, high vacua, coal tar bases,
and silicon, all by reduction of chlorides with dissociation of molecules at high temperatures,
sodium metal. He worked on the platinum metals emission and absorption spectra, soap films (he
and in 1872 was given the task of making the made them over 1 m in diameter) and the Sun™s tem-
platinum“iridium (90“10) alloy for the standard perature. A small, brusque Scot, he was unsurpassed
kilogram and metre. in diversity and productivity as an experimentalist.
Dicke, Robert Henry (1916“97) US physicist: pre-
His interest in high temperature chemistry had
begun in the 1850s and his oxy-hydrogen blowpipe dicted existence of cosmic microwave background.
method led to technical welding methods as well as Dicke studied at Princeton University and at
studies of minerals and high-melting metals. From Rochester, and in 1957 was appointed professor of
l857 he also studied vapour densities, using porce- physics at Princeton, where he became Albert
lain bulbs and the vapour of boiling metal (Hg,Cd Einstein Professor of Science in 1975.
or Zn) to give a constant high temperature. He In 1964, Dicke made the prediction that, assum-
found that relative molecular mass could change ing the universe had been created by a cataclysmic
with temperature; thus aluminium chloride is explosion (the ˜Big Bang™), there ought to be a rem-
mainly Al2Cl6 at 500°C, but AlCl3 at 1000°C. nant radiation, observable in the microwave region
Chemical changes due to heat which reverse on of the spectrum. At almost the same time, Penzias
cooling were described as dissociations by Deville, and R W Wilson did in fact observe this cosmic
who first fully examined such changes. He found microwave background, although they were
that at high temperatures H2O, CO2, CO, HCl and unaware of Dicke™s theoretical work at the time.
SO2 all dissociated. Together, their work established the ˜Big Bang™
de Vries, Hugo see Vries model of the origin of the universe as far more
Dewar, Sir James [dyooer] (1842“1923) British plausible than the rival steady-state theory.
chemist and physicist: pioneer of low temperature Interestingly, and unknown to Dicke at the time,
studies and the chemistry of metal carbonyls. Gamow and others had made a similar prediction
Son of a wine-merchant, Dewar became attracted in 1948.
to chemistry at Edinburgh University and spent a Dicke was also interested in gravitation and estab-
summer in Ghent in Kekul©™s laboratory. In 1869 lished that the gravitational mass and inertial mass
he went to teach chemistry at the Royal Veterinary of bodies are equivalent to an accuracy of at least
one part in 1011, an important result for general rel-
College in Edinburgh. Although he was never inter-
ested in teaching students, he was a popular society ativity. However, in 1961 the Brans“Dicke theory
lecturer on a wide range of scientific topics, and in suggested that the gravitational constant (G) was
1875 became Jacksonian Professor at Cambridge. not in fact constant, but varied slowly with time (by
about 10“11 per year). Unfortunately the experimen-
He was probably elected because of his work in
physiological chemistry and was perhaps expected tal observations required to verify this hypothesis
to do more of it; in fact he found the laboratory so are not yet sufficiently precise to prove it or dis-
poor that he was glad to be appointed also in 1877 prove it.
Panel: Telescopes

Section through five types of telescope
Refracting telescope

concave mirror for viewing. A claim has long been
made for Hans Lippershay (c.1570“c.1619), a
convex Dutch spectacle maker who sought a patent in
1608 for a design we would now class as Galilean.
What is certain is that such telescopes were on sale
in Paris, Milan and London in 1609 and that
GALILEO quickly heard of the device, deduced its
construction (see diagram), made several for
Reflecting telescopes
himself and within a year had seen mountains on
the Moon, sunspots, the phases of Venus and the
four larger satellites of Jupiter, all for the first time.
mirror His best telescope had a magnification of about
30 —. In the next century many more refracting
telescopes (ie using lenses only) were made. In
KEPLER™s design, a positive lens forms the eyepiece;
the image is inverted, but for terrestrial use a
second lens in the eyepiece gives an erect image.
These early telescopes were awkward to use; in
particular, as the red and blue ends of the spectrum
secondary are not brought to the same focus by a simple lens,
the image is seen to have colour fringes.
NEWTON became interested in telescopes in the
1660s, but soon decided (incorrectly) that colour
fringes were unavoidable with lenses, and in 1668,
when he was 26, he made for himself a small
plate reflecting telescope which solved this problem
principal (see diagram).
The value of a telescope in astronomy depends
largely on the area of its main lens or mirror, which
surface gathers light and so allows the eye (or a camera) to
observe small, dim, or distant objects by concen-
trating their light. F W HERSCHEL cast, ground and
polished mirrors for his telescopes (which were of
Newtonian or related type) up to 48 in (122 cm)
radio waves primary
parabolic across, with a focal length of up to 40 ft (12 m),
and used them to discover a new planet (Uranus),
to examine nebulae (clouds of luminous gas or
dust) and to show that the Milky Way is dense with
stars. The mirrors were made of an alloy of copper
receptor and tin, and soon tarnished. In the 1840s the Earl
part of
radiotelescope of Rosse made similar mirrors 72 in (183 cm)
array wave guide
across, but the unsuitable climate of Birr Castle
and Parsonstown, his estate in Eire, gave few clear
nights to use his massive instruments.
Refracting telescopes were restored to favour
wave guide
after DOLLOND began making achromatic lenses
to control centre
made of two components: one of crown glass and
one of flint glass, a combination that largely solved
It is not clear who made the first telescope. It may the colour problem. However, a large lens requires
well have been LEONARD DIGGES, who probably two good surfaces and fairly flawless glass
made a telescope about 1550, with a convex lens between them, and the largest in use is a 40 in
whose image was reflected to the side by a (1 m), with focal length 62 ft (19 m), in the USA.

Diels, Otto

In this century reflectors have proved dominant: ultraviolet spectrum had been used in satellites in the
usually of Pyrex glass, silvered or aluminized, driven 1970s. By 1986 the space probe Giotto passed close
electrically to follow the apparent motion of the to HALLEY™s comet and transmitted TV pictures of its
stars, and linked to a spectroscope, a camera or an nucleus to Earth (see chronology); in 1990 satellites
electronic detector (a CCD, charge-coupled device) were launched carrying a telescope to detect X-ray
rather than a human eye. Their massive mountings sources among stellar objects (ROSAT), and a 95 in
provide a substantial engineering problem: in the (2.4 m) reflecting telescope (named after HUBBLE) to
first half of the 20th-c high locations in California observe deep space. The Hubble Space Telescope,
were favoured, and 60 in (1.5 m), 100 in (2.5 m) and after repairs in space had corrected some defects,
200 in (5 m) instruments are used in the Mount proved to be excellent, and entirely free from
Wilson and Mount Palomar Observatories there. But unwanted effects due to the Earth™s atmosphere; the
atmospheric pollution and light pollution from cities data are transmitted by radio. The period 1950“2050
have proved a problem, and recent large instruments should be a golden age for astronomy, with new
have been placed at high points in Hawaii, information becoming available at an unprecedented
Las Palmas and Chile to reduce this. One of the rate. At last, after 380 years, astronomers have
largest (but of inferior optical quality) is the 6 m escaped from the great restriction on their
(236 in) reflector installed in 1969 on Mt Pastukhov observational work, the Earth™s atmosphere.
in the northern Caucasus. At the time of writing, the world™s largest optical
Telescopes can also be designed to detect radi- telescope is the Keck I, on the summit of Mauna Kea
ation outside the visible range, and the radio, (4200 m/13 780 ft), Hawaii. It weighs 297 t, and the
ultraviolet, infrared and X-ray regions are all much mirror system is 10 m in diameter and consists of 36
studied. The Second World War gave a great impetus hexagonal segments fitted together. Its huge size
to astronomy, wartime radar and rocket missiles and good location enable it to record very distant and
giving a basis for major advances. Radio astronomy faint objects, allowing better estimates to be made of
stemmed from work by JANSKY and REBER, who the size and age of the universe than any made previ-
showed that the stars included radio sources, studied ously. With its nearby sibling Keck II complete, the
after the war by HEWISH, OORT, LOVELL and others. An paired system, used as an optical interferometer,
infrared astronomical satellite (IRAS) was launched in gives high resolution: and the key role of optical
1983, with a 24 in (61 cm) reflecting telescope for astronomy will be reaffirmed.
infrared rays; it survived for 10 months and located
many infrared sources. Telescopes for use in the

Diels, Otto (Paul Hermann) [deels] (1876“1954) discovered the valuable general synthesis now
German organic chemist: co-discoverer of Diels“ known as the Diels“Alder reaction. In this, a con-
Alder reaction. jugated diene reacts by 1,4-addition with one
A member of an academically talented family, of a large group of unsaturated compounds
Diels studied chemistry in Berlin with E Fischer. (dienophiles) to give, usually, a six-membered ring
Most of his life was spent in the University of Kiel. compound as the product. The method has proved
In 1906 he discovered a new oxide of carbon (the of great value in the synthesis of complex organic
monoxide and dioxide were long known); he made compounds. Diels and Alder shared a Nobel Prize in
tricarbon dioxide (C3O2) by dehydrating malonic 1950.
Diesel, Rudolph (Christian Karl) (1858“1913)
acid with P2O5:
CH2(CO2H)2 “ 2H2O ’ O=C=C=C=O German engineer: devised the compression-igni-
He showed in 1927 that cholesterol is dehydro- tion internal combustion engine.
genated by heating with selenium and that the Born in Paris of German parents, Rudolph and his
hydrocarbon products include one of melting point family left for London when the Franco-Prussian
127°C, now known as Diels™s hydrocarbon. The war of 1870 began but he soon moved to Germany
method can be applied generally to steroids, and to continue his education, eventually studying at
many yield Diels™s hydrocarbon; in this way and by the Munich Polytechnic.
interconversions this biologically important steroid From 1880“90 he worked on refrigeration plant,
group was shown to all have the same carbon skele- but his interest was in engines. He realized that on
ton. By 1934 Diels™s hydrocarbon had been synthe- thermodynamic principles an internal combustion
sized by others and its structure was the critical clue engine should desirably operate with a large tem-
that allowed other steroid structures to be assigned, perature range, which implies a high pressure. His
all containing the four-ring skeleton of Diels™s hydro- patent of 1893 and his engines produced in the late
carbon: this skeleton became the defining feature of 1890s use a four-stroke cycle like the Otto engine
steroids. (induction, compression, combustion, exhaust) but
In 1928, with his assistant K Alder (1902“58), Diels in the Diesel engine a higher-boiling petroleum
Dirac, P A M

fraction is used. In the induction stroke, air alone is Office. In 1901 he invented his pressure-tube
drawn into the cylinder. On the compression stroke anemometer, the first device to measure both the
this air is compressed by up to 25:1 (unlike the 10:1 direction and the velocity of wind. He was an early
compression of the petrol:air mixture in a petrol user of kites and balloons to study the upper
engine) and this raises its temperature to near atmosphere, devising an ingenious meteorograph,
600°C. Then an injector admits a fine spray of fuel weighing only 60 g, to measure and record upper-
into the heated air; it ignites spontaneously, and air soundings. From about 1907 his device gave
the combustion stroke provides power. An exhaust data on pressure, temperature and humidity at
stroke to remove the burned gas completes the heights up to and including the stratosphere, and
cycle. Diesel prospered, but in 1913 he vanished became a standard instrument for this purpose. His
from the Antwerp“Harwich mail steamer and was work on these data showed new correlations
presumed drowned; his body was never found. between measurable properties of the upper air
Diesel engines are more efficient than petrol and gave improved understanding of cyclones and
engines and were used in the First World War in anticyclones, showing for example that their circu-
submarines, and later in ships and rail locomotives. lation is not greatly affected by thermal processes
The smaller units for buses, tractors, trucks and near the Earth™s surface.
Diophantus (of Alexandria) [diyohfantuhs] (lived
small electrical generators were developed in the
1930s, with important design contributions by two c.250) Greek mathematician: discoverer of the
British engineers, C B Dicksee (1888“1981) and H R Diophantine equations.
Ricardo (1885“1975); by the 1980s larger commer- Although an outstanding mathematician of his
cial vehicles were normally powered by high-speed time, very little is now known about Diophantus™s
compression- ignition units. life. His work is preserved in the six surviving chap-
Digges, Leonard (c.1520“59) and Thomas Digges ters of his Arithmetica (a further seven chapters have
(c.1546“1595) English mathematicians, surveyors been lost), which was probably the earliest system-
and probable inventors of the telescope. atic treatise on algebra. Diophantus was primarily
Following his studies at Oxford, Leonard Digges interested in number theory and the solution of
published his book Prognostication which sold well in equations and did much to advance algebra by his
various editions from 1553. It contained astronomi- use of symbols for quantities, mathematical opera-
cal, astrological and meteorological tables and tions and relationships; previously such quantities
advice, and was followed in 1556 by a book on prac- had been described in words. He is perhaps best
tical surveying. However, in early 1554 he took part, remembered as the discoverer of the Diophantine
with others from his county of Kent, in a nationwide equations, indeterminate equations with rational
revolt against a Catholic royal marriage. The revolt coefficients for which a rational solution is
was easily suppressed and its leaders beheaded; required.
Dirac, P(aul) A(drien) M(aurice) (1902“84) British
Digges was also condemned but later reprieved.
When he died aged 39, he left his 13-year old son theoretical physicist: major contributor to quan-
Thomas in the care of the mathematician John Dee tum mechanics; predicted existence of the positron
(1527“1608) and the boy grew up with the same and other antiparticles.
interests as his father. In 1571, when he was 25, Dirac, the son of a Swiss father and English
Thomas published Pantometria, a book on surveying mother, studied electrical engineering at Bristol
originally drafted by his father and ˜lately finished™ and mathematics at Cambridge. After teaching in
by Thomas himself. It contains a description of a America and visiting Japan and Siberia, Dirac was
telescope using a lens and a mirror; this is ampli- appointed in 1932 to the Lucasian professorship in
fied in a report prepared for Elizabeth I™s govern-
ment in 1585, which credits the device to Leonard
Digges and his son and which clearly has in mind
its military uses. It is likely that Thomas Digges
used it to observe the sky and was impressed by the
great number of stars it made visible.
However, the effective beginning of observa-
tional astronomy came with Galileo™s work in
1610, when he used a refracting telescope made by
himself and first saw mountains on the moon, the
phases of Venus, Jupiter™s satellites and sunspots.
Improved designs of reflecting telescopes due to
Gregory and to Newton set these reflectors on the
path of dominance for astronomical use which
they later achieved (see panel ˜Telescopes™).
Dines, William Henry (1855“1927) British meteo-
rologist: devised methods for study of the upper
A meteorologist™s son, Dines studied at Cambridge
and afterwards worked for the Meteorological P A M Dirac
Dirichlet, Peter Gustav Lejeune

mathematics at Cambridge, where he remained for a Fourier series to converge (those conditions
until his retirement in 1969. He was then a visiting necessary for it to converge are still undiscovered).
lecturer at four US universities before becoming He worked on multiple integrals and the boundary-
professor of physics at Florida State University in value problem (or Dirichlet problem), which is the
1971. effect of the conditions at the boundary on the solu-
A uniquely gifted theoretician, Dirac contributed tion of a heat flow or electrostatic equation.
creatively to the rapid development of quantum It is not only Dirichlet™s many specific contribu-
mechanics. In 1926, just after Born and Jordan, he tions that give him greatness, but also his approach
developed a general theoretical structure for quan- to formulating and analysing problems for which
tum mechanics. In 1928 he produced the relativis- he founded modern techniques.
Döbereiner, Johann Wolfgang [doeberiyner]
tic form of the theory, describing the properties of
the electron and correcting the failure of (1780“1849) German chemist: introduced Law of
Schrödinger™s theory to explain electron spin, dis- Triads and studied catalysis.
covered by Uhlenbeck and Goudsmit in 1925. A coachman™s son, Döbereiner was largely self-
From the relativistic theory he proposed in 1930 educated, but secured a teaching post at Jena, pos-
that the theoretically possible negative energy solu- sibly through aristocratic influence. He held the
tions for the electron exist as states but these states teaching post through his lifetime; one of his
are filled with particles of negative energy so that pupils was the philosopher Goethe. He improved
other electrons cannot enter them. He predicted organic analysis and made the first estimates of the
that a sufficiently energetic photon could create an abundance of elements in the Earth™s crust. He
electron“positron pair apparently from nowhere used an earlier observation by Davy (that platinum
by knocking an electron out of one of these nega- caused organic vapours to react with air) to devise
tive energy states. The positively charged hole left is Döbereiner™s lamp, a toy or demonstration device
the antiparticle to an electron, called a positron. in which a jet of hydrogen was ignited by contact
Also, an electron meeting a positron can give with platinum sponge. His main claim to fame is
mutual annihilation, releasing energy as a photon his observation of ˜trias™ (later, triads) of elements.
(light). All these predictions were observed experi- These are groups such as Cl, Br, I; or Ca, Sr, Ba; or S,
mentally by C D Anderson in 1932. Dirac™s argument Se, Te; in which the atomic mass of the middle ele-
applies to all particles, not just electrons, so that all ment is close to the mean of the first and last ele-
particles possess corresponding antiparticles. ments in its group and its physical and chemical
In 1930 Dirac published The Principles of Quantum properties likewise appear average. By 1829 this
Mechanics, which is a classic work which confirmed was developed as the Law of Triads. It then
his stature as a 20th-c Newton in the minds of attracted little attention, but can now be seen as a
many physicists. The Nobel Prize for physics for step towards the periodic classification of the ele-
1933 was shared by Dirac and Schrödinger. ments.
Dirichlet, Peter Gustav Lejeune [deereeshlay] Dobzhansky, Theodosius [dobzhanskee] (1900“
(1805“59) German mathematician: contributed to 75) Russian“US geneticist: linked Darwin™s ideas of
analysis, partial differential equations in physics evolution with Mendel™s laws of genetics and so
and number theory. was a creator of evolutionary genetics.
Dirichlet studied at Göttingen under Gauss and He studied zoology in Kiev and later taught there
Jacobi and also spent time in Paris, where he and in St Petersburg before, in 1927, joining
gained an interest in Fourier series from their orig- Morgan™s research group working on Drosophila
inator. He moved to a post at Breslau but at 23 genetics in Columbia University, New York City.
became a professor at Berlin, remaining for 27 Morgan, a major figure in modern genetics, moved
years. He was shy and modest but an excellent to California in 1928, and Dobzhansky joined him
teacher; he was a close friend of Jacobi and spent the following year and spent his later career there
18 months in Italy with him when Jacobi was and in New York.
driven there by ill-health. On Gauss™s death in 1855 Dobzhansky™s book Genetics and the Origin of Species
Dirichlet accepted his prestigious chair at Göttingen (1937) brought together the ideas of field natural-
but died of a heart attack only 3 years later. ists and geneticists, both experimental and mathe-
Dirichlet carried on Gauss™s great work on matical, to create a single argument on the process
number theory, publishing on Diophantine equa- of evolution. His work with Drosophila had made
tions of the form x5 + y5 = kz5, and developing a gen- him very aware that natural mutations can lead to
eral algebraic number theory. Dirichlet™s theorem large or small apparent changes, that these are
(1837) states that any arithmetic series a, a + b, acted upon by natural selection and that genes may
a + 2b, a + 3b, where a and b have no common interact and so give rise to variation which appears
divisors other than 1, must include an infinite continuous rather than stepwise. He showed that
series of primes. His book Lectures on Number Theory natural selection could be seen in action, for exam-
(1863) is a work of similar stature to Gauss™s earlier ple in the spread of scale insects resistant to control
Disquisitiones and founded modern algebraic number by cyanide gas, used as an insecticide in Californian
theory. citrus groves.
Dirichlet also made advances in applied mathe- Dobzhansky developed good arguments for his
matics. In 1829 he stated the conditions sufficient view that a new species cannot arise from a single
Doppler, Christian Johann

mutation and that, for a new species to form, it however, he joined his son Peter in his business as
must for a period be isolated to protect it from dis- an optician. They attacked the problem of chro-
ruption. The isolation could be geographical or due matic aberration, ie the colour fringes in the
to differences in habitat or in the breeding season. images produced by a simple lens, which Newton
His work on human evolution led him to define had considered inherent in lenses. In fact C M Hall
races as ˜Mendelian populations which differ in (1703“71), a London lawyer, had designed a com-
gene frequencies™, as outlined in his Genetics of the pound lens of crown and flint glass which was
Evolutionary Process (1970). largely achromatic (colour-free) and had telescopes
Doisy, Edward Adelbert [doyzee] (1893“1986) US made using them, from 1733. The Dollands almost
biochemist: isolated vitamin K. certainly knew of this; however they did much
Educated at Illinois and Harvard, Doisy spent experimental work, secured improved glass and,
most of his life at St Louis University Medical after John Dolland™s patent of 1758, produced good
School. In 1923 he devised a bioassay for the female quality achromats. This led to nearly colour-free
sex hormone and secured potent extracts, but it refracting telescopes being made; although the
was Butenandt who first isolated oestrone. Soon reflecting type ultimately became dominant in
Doisy moved to the study of vitamin K, discovered astronomy, as a mirror is completely achromatic,
but not isolated by Dam in 1934, deficiency of requires only one flaw-free surface and can be sup-
which leads to the blood failing to coagulate. Doisy ported from the back. In microscopy Dolland-type
was able to isolate a factor (K for koagulation) from lenses were of great value, as there is no easy alter-
alfalfa grass, and a related but different K factor native to a refracting system for obtaining optical
from putrefied fish meal. These two potent anti- magnification in the microscope.
Domagk, Gerhard [dohmak] (1895“1964) German
haemorrhagic vitamins, K1 and K2, were shown by
Doisy to be derivatives of 1,4-naphthoquinone; biochemist: discoverer of sulphonamide antibacte-
such compounds are valuable in therapy, for exam- rial drugs.
ple to reduce bleeding in patients with an Ehrlich™s success in treating some protozoal dis-
obstructed bile duct. Doisy shared a Nobel Prize eases by chemotherapy had led to high hopes of
with Dam in 1943. similar success in the treatment of bacterial dis-
Doll, Sir Richard (1912“ ) British epidemiologist: eases. Diseases due to protozoa are common in the
showed relationship of smoking with lung cancer. tropics; in temperate regions, diseases due to the
Trained in medicine in London, Doll served in the smaller bacteria are major problems. However, by
RAMC (Royal Army Medical Corps) throughout the 1930 hopes had faded; trial compounds usually
Second World War and afterwards worked with the failed to be effective in the presence of blood or pus.
Medical Research Council (1946“69) and in Oxford This was the position when Domagk began work on
as Regius Professor of Medicine (1969“79). His first the problem. He had qualified in medicine at Kiel in
job in epidemiology in 1944 was directed, unsuccess- 1921 and in 1927 began to direct research at the
fully, to finding if peptic ulcers were linked with bacteriology laboratory of I G Farbenindustrie at
long working hours. Then, with R Peto (1943“ ), Wuppertal, while retaining a position at the
he established in the 1950s that cigarette smoking University of Münster. His scheme was to test a
is causally linked with lung cancer, a result in series of new carpet dyes made by I G Farben, trying
accord with the fact that tobacco smoke, like tar them as drugs against streptococcal infections in
and soot, contains the carcinogen benzo[a]pyrene. mice, and in 1932 he found that the dye Prontosil
A massive study was begun of the health of 35 000 Red was highly effective. Human trials soon fol-
doctors, continued for over 40 years. lowed and included a dramatic cure of Domagk™s
Then he studied the relation between exposure to daughter, who had a serious sepsis following a
low levels of high energy radiation and cancer; the needle prick. In 1936 a French group including
worldwide nuclear test ban treaty owed something Bovet found that Prontosil is converted in the body
to this work. In the 1960s he examined the side into the rather simple compound sulphanilamide,
effects of the contraceptive pill; the oestrogen level which is the effective agent. It had been known
in these was later changed to reduce the slight risk since 1908, was cheap and unpatentable and does
of thrombosis his work had revealed. His later work not discolour the patient. Treatment of bacterial
examined the effects of radiation in inducing can- infections (for example pneumonia and streptococ-
cers in servicemen who attended the early nuclear cal infections) was vastly improved by the use of sul-
weapon tests, in populations living near nuclear phanilamide and related ˜sulpha™ drugs such as
power plants and in households living under over- M&B 693. After 1945 penicillin and other antibi-
head power lines or above radon-emitting rock. His otics became dominant, but sulpha drugs remain
work showed that risks were very low in these valuable. Domagk was awarded a Nobel Prize in
cases, except for the last, in which underfloor ven- 1939, but was not able to accept the medal until
tilation should be installed. 1947 as his country was at war. The Nobel rules did
Dolland, John (1706“61) British optician: intro- not allow him to have the prize money after such a


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