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could be emitted only in ˜packets™ of a minimum between particles and the mirror image of those
energy (which he called quanta), then a radiation particles will be identical, and this was accepted to
law could be calculated that was obeyed accurately apply to all types of reaction. However, very sur-
at all wavelengths. Planck published his quantum prisingly, Lee and Ting identified a class of excep-
theory in 1900, aware that its assumptions had no tions to this law of parity conservation in 1958.
justification in classical physics and yet, as they Reactions involving the weak nuclear force, such as
appeared correct, a major revolution in physical beta decay when an electron is emitted from a
science was inevitable. Wien was awarded the nucleus, do not conserve parity.
Nobel Prize for physics in 1911. Wigner™s research during the 1930s mainly con-
Wiener, Norbert [weener] (1894“1964) US mathe- cerned neutrons and he investigated the strong
matician: established the subject of cybernetics. nuclear interaction which binds neutrons and pro-
As a child Wiener showed his mathematical tons in the nucleus. He showed that the force has a
talent early, but his career then became erratic. At very short range and does not involve electrical
15 he entered Harvard to study zoology; he changed charge. The formula describing how moving neu-
to philosophy at Cornell and got a PhD from trons interact with a stationary nucleus was given
Harvard in mathematics at 19. He then studied by Breit and Wigner in 1936. Using this and other
logic briefly under B Russell (1872“1970) and discoveries, Wigner assisted Fermi in constructing
Hilbert. Suffering perhaps from too rapid an edu- the first nuclear reactor to produce a sustained
cation, Wiener drifted through various activities, nuclear chain reaction in Chicago in 1942. For his
376
Williams, Cicely

contributions to quantum theory and applying it to Whilst proving the Last Theorem may appear to
nuclear physics Wigner shared the 1963 Nobel be of little practical purpose, the series of new
Prize for physics. mathematical techniques developed by Wiles in
Wiles, Sir Andrew John (1953“ ) British math- the process of his proof, together with the proof of
ematician: proved Fermat™s Last Theorem. the Taniyama“Shimura Conjecture, and his result-
Wiles was born and in part educated in ing linkage between elliptic equations and modular
Cambridge. When only ten years old, he became forms, has revolutionized mathematics, and enabled
fascinated by Fermat™s Last Theorem, which states others to attack a wide range of other problems.
that there are no solutions for xn + yn = zn where n > 2. Wiles was knighted in 2000. He held a professor-
This theorem (more accurately a conjecture) had ship of mathematics at Princeton from 1982“8 and
first been proposed by Pierre de Fermat sometime from 1990 onwards.
Wilkes, Maurice Vincent (1913“ ) British mathe-
around 1637. Typically of Fermat, he had not writ-
ten down his proof, but had scribbled the equation matician and computer scientist: designed the first
in the margin of a book together with the note ˜I delay storage computer.
have discovered a truly marvellous demonstration Wilkes was educated at Cambridge, subsequently
of this proposition, which this margin is too narrow taking positions there as lecturer and director of
to contain.™ Although a small number of specific the Mathematical Laboratory, and head of the
cases were soon proved (for n = 3 and 4, etc.), and Computer Laboratory.
later for all values of n up to 125 000, the combined After wartime work on radar and operational
efforts of generations of mathematicians, over the research, Wilkes worked on the early development
following three and a half centuries, failed to pro- of computers, leading the team which built EDSAC
vide a general proof, and many believed that (Electronic Delay Storage Automatic Calculator),
Fermat must have been mistaken, and that the the first machine to use delay lines to store infor-
theorem was inherently unprovable. mation. The delay lines were mercury-filled tubes
After completing a first degree at Oxford, and a (1.5 m long) with piezoelectric crystals at either
Cambridge doctorate on the subject of elliptic end; incoming signals generated a pressure pulse
curves, Wiles moved to Princeton in the 1980s. Late which was transmitted through the mercury to the
in 1986 he decided to focus on the proof of Fermat™s second crystal, where it was converted back into an
Last Theorem, a topic he worked on single-mindedly electrical impulse. Several such devices and suit-
and in secret until 1993, when he announced his able amplification allowed an electrical signal to be
proof. Unfortunately, a flaw was soon found in his stored indefinitely, an essential requirement of a
logic, but a year and a half later he was able to computer ˜memory™. EDSAC ran its first program
resolve this satisfactorily, and the final proof was in 1949 and was a milestone in the development
published in 1995. of computers. EDSAC II, in service from 1957,
Wiles™s proof, which runs to over 100 pages, can included among its improvements the use of
probably only be fully understood by a small magnetic storage in place of delay lines. Wilkes
group of fellow number theorists, but it builds on continued to play a leading role in computer devel-
work by a German mathematician, Gerhard Frey, opment.
Wilkinson, Sir Geoffrey (1921“96) British inor-
who had shown that that if Fermat™s Last Theorem
is true, then the Taniyama“Shimura Conjecture ganic chemist: carried out important work on the
(which proposes that every elliptic equation has an structure of metallocene compounds and transi-
equivalent modular form) must also be true. Wiles tion complexes.
succeeded in proving the Taniyama“Shimura Con- Wilkinson, born in Todmorden, Yorkshire, studied
jecture to be true, and therefore the Last Theorem at Imperial College London. After 13 years in Canada
also. and the USA he returned to London in 1956 as pro-
fessor of inorganic chemistry. While at Harvard
University in 1952 he published with Woodward
and others a paper on the remarkable compound
(C5H5)2Fe, ferrocene. They showed that this has a
structure with an iron atom sandwiched between
two flat five-carbon rings. Thousands of ˜sandwich
type™ molecules have now been made, containing
other metals and other-sized rings (the ˜metal-
locenes™); even three-decker sandwiches are known.
For his work on metallocenes Wilkinson shared the
1973 Nobel Prize with E O Fischer (1918“94) of
Munich, who had worked independently on similar
lines. Wilkinson also worked on transition metal
complexes, and discovered the first homogeneous
system for catalytic hydrogenation of C=C bonds by
use of the rhodium complex RhCl[P(C6H5)3]3.
Andrew Wiles announcing his results on Fermat™s Last
Williams, Cicely (1893“1992) British paediatrician:
Theorem in 1993 at the Isaac Newton Institute for
identified the condition known as kwashiorkor.
Mathematical Sciences, Cambridge, England.
377
Williamson, Alexander William

Williamson, Alexander William (1824“1904)
Cicely Williams was born in Jamaica, of a land-
owning family that had been there since the 17th-c. British chemist: demonstrated the chemical rela-
She was educated in England at the Bath High tionship between alcohols and ethers.
School for Girls and at Somerville College, Oxford, Born in London, Williamson lived with his par-
where she read medicine. She was one of the first 50 ents on the Continent, studied chemistry in France
female undergraduates to have their degrees con- and Germany and became head of chemistry at
ferred in the Sheldonian Theatre in 1920. She University College, London. He is remembered for
trained at Queen™s College Hospital for Children, the Williamson synthesis of ethers, in which a
Hackney and at King™s College, Camberwell, but sodium alkoxide reacts with an alkyl halide, ie
RONa + R1I ’ ROR1 where R,R1 are alkyl groups.
found it difficult to get a medical post, partially
because of the priority given to returning ex-ser- By use of this reaction (1851) the relation between
vicemen. After a year as a medical officer in Greece alcohols and ethers became clear. As he lacked one
she joined the Colonial Health Service and, after a eye and had only one usable arm, Williamson™s
wait of 2 years, was appointed to the Gold Coast prowess as a practical chemist is surprising.
Willis, Thomas (1621“75) English anatomist: made
(now Ghana). Here she found a condition that
results from dietary protein deficiency due to a important studies of anatomy of the brain.
high intake of carbohydrate of low nutritional Willis studied classics and then medicine at
value. This nutritional deficiency disease causes Oxford; for a time he served in the Royalist army in
the abdomen to swell, the hair to turn red, the the Civil War. He was one of the small group of
liver to enlarge and life-long ill-effects in children ˜natural philosophers™ (including Boyle) who met
under 2. This disease has ravaged children in in Oxford in 1648“9 and who were founder mem-
drought and war-torn areas of maize-eating Third bers of the Royal Society of London. His main work
World countries. was on the anatomy of the brain; the softness of
Cicely Williams first described the condition in brain tissue makes study of its circulation difficult,
the 1931“2 volume of the annual medical report of but Willis improved on earlier work by injecting
the Gold Coast. The reaction of medical editors in the vessels with wax; he thus saw the ring of vessels
London was to reject her paper; as she said, ˜They now known as ˜the circle of Willis™. He also worked
could not concede that a woman in the Gold Coast on fevers and he described a type of diabetes in
of all places had anything to say which concerned which the excessive urine has a sweet taste. In 1776
them™. However the paper was then published in this was found to be due to sugar, and in the 1920s
The Lancet and here the condition was named and this disease (diabetes mellitus) was brilliantly
described for the first time in medical terms. She explored and effectively treated by Banting and C
used a word, kwashiorkor (from the local language, H Best (1899“1978). Willis was also the first to pro-
Ga), which means ˜neglect of the deposed™, to pose that the essential feature of asthma is spasm
describe the condition. of the bronchial muscles.
Willst¤tter, Richard [vilshteter] (1872“1942)
After 7 years in Africa Williams was transferred to
Malaya and was in a remote province when in 1941 German organic chemist: discovered the structure
Pearl Harbor was attacked. After weeks of hardship of chlorophyll.
and danger she reached Singapore just as the Willst¤tter was 11 when his father left Germany
Japanese invaded. Imprisoned in the notorious for New York to establish a clothing factory, follow-
Changi jail she became its chief doctor and was ing the successful example of his brothers-in-law.
proud of the fact that the 20 babies born there all An expected short separation lengthened to 17
survived. In 1943 she was taken to the headquarters years as success came to him slowly; and it was his
of the Kempe Tai, the equivalent of the Gestapo, wife and her family who brought up his two sons.
and interrogated as a spy, spending 4 months in a Richard™s interest in chemistry was prompted by
cage in which she could only crouch, along with the visits to his uncle™s factory for the production of
dead and the dying. carbon for batteries.
After the war she was sent to America for recu- He graduated at the University of Munich, stud-
peration and postgraduate study at Johns Hopkins ied under Baeyer and gained his PhD in 1894 for
University. In 1948 she was appointed the first head work on alkaloids. He obtained a professorship at
of the Mother and Child Care unit at the World the University of Zürich (1905“12) and worked on
Health Organization in Geneva. From 1959 she plant pigments, quinones and the chemistry of
became visiting professor of maternal and child chlorophyll. Using the chromatographic technique
health at the American University of Beirut and developed by Tswett he worked out the structure
from 1964 overseas training adviser to the Family of both the a and b form of chlorophyll. He showed
Planning Association. Cicely Williams was the first that chlorophyll contains a single atom of magne-
woman to be given an honorary fellowship of the sium in its molecule, rather as haemoglobin con-
Royal Society of Medicine (1977). In 1985, aged 92, tains a single iron atom. His work on cocaine
she became a Fellow of Green College, Oxford. derivatives, begun in Munich, led to the synthesis
She was a pioneer of women™s place in the of new medicinals and the chemical curiosity cyclo-
medical profession and her ideas and methods octatetraene. He was awarded the Nobel Prize for
of treatment in paediatrics are now followed chemistry in 1915 for his work on plant pigments.
internationally. He returned in 1912 to the Kaiser Wilhelm
378
Wilson, Edward Osborne

Institute at Berlin“Dahlem where he worked on the division then triggered by an electric spark. (This
carotenes and anthocyanins. During the First step somewhat recalls Mary Shelley™s 19th-c sci-
World War Willst¤tter worked on gas masks and ence-fiction novel, Frankenstein.) The embryo was
devised a filling of hexamethylenetetramine to then brought to term in a sheep™s womb to give a
absorb phosgene; layered with active carbon it was lamb (Dolly) genetically identical with the donor of
effective against the gases of the time. In 1916 he the nucleus. Success came after 450 attempts by the
succeeded Baeyer to the chair in Munich and team led by Wilmut at the Roslin Institute. By 1998
worked on photosynthesis, with A Stoll (1887“?), clones of mice and calves were made by related
and on enzymes, notably catalase and peroxidase. methods, at Edinburgh and elsewhere. Animal
In 1925 he resigned his professorship in Munich cloning could be used to replicate ˜elite™ animals:
in protest against increasing anti-semitism, in par- and to produce humanized tissues, organs and pro-
ticular his faculty™s rejection of the appointment of teins for medical use. In principle human cloning is
V M Goldschmidt, the geochemist, because he was a possibility but is widely seen as undesirable.
Wilson, Charles Thomson Rees (1869“1959)
Jewish. Willst¤tter had resigned his post at 53 with-
out a pension, and losing the house, the status and British physicist: the inventor of the Wilson cloud
the protection that went with it. chamber.
He was now alone “ his wife had died many years Wilson left a Scottish sheep farm as a child of 4,
before after only 5 years of marriage, shortly to be and was educated in Manchester, eventually as a
followed by the death of a small son. His daughter biology student there. Then he went to Cambridge,
had married and was living in the USA. Despite did well in physics and became a teacher in
many offers of posts in other countries he wished to Bradford for 4 years before returning to Cambridge
stay in his own country. The next few years were in 1896 and staying there for a long career.
spent in travelling, lecturing and continuing what In 1894 he had been attracted by the brilliant
research he could, with the help of Margarete cloud effects he observed from the summit of Ben
Rohdewald who was allowed space in the labora- Nevis, and in Cambridge he examined methods of
tory and who reported her findings by telephone. producing artificial clouds in the laboratory by the
It was she who in November 1938 heard that sudden expansion of moist air. The expansion
members of the National Socialist party had been drops the temperature of the gas and the water
requested to volunteer for the arrest of Jews and vapour partly condenses as droplets on the walls
warned Willst¤tter. He was able to avoid an imme- and on any available nuclei. Wilson showed that if
diate journey to Dachau, but he then knew he had filterable dust is absent, then charged ions (pro-
to leave Germany to survive. He was determined to duced eg by X-rays) will serve as nuclei. By 1911 he
emigrate to Switzerland in a proper manner, but had devised his cloud chamber, in which the path
his patience and dignity were to be tested in the fol- of an ion is made visible as a track of water droplets.
lowing months while he was gradually stripped of It was soon used to detect and examine the alpha-
his possessions in return for his passport. With help and beta-particles from radioelements, and it
from his former student Stoll and influential quickly became a favourite device for particle
friends in Switzerland he crossed the border in physicists, especially in the 1920s and 1930s. It was
March 1939. also the ancestor of the bubble chamber devised by
Wilmut, Ian (1944“ ) British embryologist: led Glaser in the 1950s.
team which produced the first clone from a Another of Wilson™s researches also began on Ben
mammal (a sheep) using adult cells. Nevis, as a result of his own electrification (his hair
Wilmut studied biology at Nottingham, and stood on end) during a storm in 1895. He studied
worked for his doctorate at Cambridge in embryol- electrical effects in dry and moist air and he noted
ogy. There he studied the effect of freezing on pig that a sensitive, well-insulated electrometer shows
semen, and by 1973 he had produced the first calf slow leakage, by day or night, even underground;
obtained by using a frozen embryo. From 1974 he he concluded that radiation from sources outside
was at the Roslin Institute, Edinburgh (formerly the the atmosphere might be the cause. In 1911 V F
Animal Research Breeding Station). From the 1980s Hess studied this further, and the discovery of
he was concerned with cloning. A clone is derived cosmic rays proved that Wilson was right. His inter-
from a single progenitor by asexual means: it there- est in atmospheric electricity remained; in his long
fore has a near-identical genetic constitution. A retirement in Scotland, he flew at age 86 over the
rooted vegetative cutting is a plant example. In Outer Isles to observe thunderstorms, and presented
1995 Wilmut and his co-workers produced two his last paper on this subject, aged 87. He shared the
sheep cloned from differentiated embryo cells; but Nobel Prize in 1927 for his cloud chamber.
Wilson, Edward Osborne (1929“ ) US biologist:
their best-known success was achieved in 1996,
when they produced a cloned lamb from the adult creator of sociobiology.
cells of its single parent. (The lamb was named Educated at Alabama and Harvard, Wilson taught
Dolly after the singer Dolly Parton.) Cloning of a at Harvard from 1956. He is best known for his
mammal from adult tissue had been achieved for remarkable work on social insects and its wider
the first time. The nucleus of a mammary gland cell implications in animal behaviour and evolution.
from a 6-year-old Finn Dorset sheep was implanted In developing his theory on the interaction and
into an emptied egg from another sheep, and cell equilibrium of isolated animal populations, he and
379
Wilson, John Tuzo

rather than one sinking beneath the other in a sub-
duction zone. Mid-ocean ridges often consist of a
series of offsets connected by transform faults.
Wilson, Kenneth Geddes (1936“ ) US theoretical
physicist: discovered the renormalization group
technique for treating phase transitions.
While one phase or another of a physical system
may be easily analysed theoretically, similar analy-
sis of the transition between phases had proved vir-
tually impossible. This is because the length scale
on which physical interactions are taking place
changes rapidly through many orders of magni-
tude. In 1974 Wilson developed the first technique
able to cope with such transitions, which are called
critical phenomena. An example is the onset of fer-
romagnetism in a magnet cooled below the Curie
point, when the atoms interact with each other and
become aligned over large volumes of the magnet.
The distance over which ordering of atomic spins
occur goes from an atomic diameter to many thou-
sands of diameters under a very small change in
E O Wilson
temperature.
D S Simberloff (1942“ ) experimented on some L Kadanoff (1937“ ) had suggested that the effec-
small islands in the Florida Keys. They first sur- tive spin of a block of atoms should be found and
veyed the insect species present (75 of them) and then a renormalization (or scaling) transformation
then eliminated all insect life by fumigation. Study made to calculate that of a larger block made up of
of the recolonization of the islands by insects over the small blocks. Wilson developed this method
some months showed that the same number of and showed how to calculate the properties of large
species became re-established, confirming their numbers of atoms strongly interacting with each
prediction that ˜a dynamic equilibrium number of other, as in magnetic systems, metal alloys or
species exists for any island™. Wilson went on to liquid-to-gas transitions. He was awarded the Nobel
consider biological and genetic controls over social Prize for physics in 1982.
Wilson, Robert Woodrow (1936“ ) US physicist:
behaviour and organization in a variety of species
in his book Sociobiology: the New Synthesis (1975), co-discoverer of the cosmic microwave background
which virtually created a new subject, integrating radiation.
ideas on the behaviour of a range of species from Wilson graduated at Rice University, Houston
termites to man. The work has both stimulated and California Institute of Technology. Thereafter
valuable research and provoked vigorous discus- he took up a post at the Bell Laboratories, Holmdel,
sion through its extension of ideas on animal NJ and became head of the radiophysics research
behaviour to include human cultural and ethical department in 1976.
conduct. At Bell, Wilson collaborated with Penzias in
Wilson, John Tuzo (1908“93) Canadian geophysi- experiments using a large radio telescope designed
cist: proposed the concept of the transform fault in for communication with satellites. In 1964 they
plate tectonics, and the ˜hot spot™ theory for the detected a radio noise background coming from all
creation of mid-ocean islands. directions; it had an energy distribution corre-
Wilson worked for the Canadian Geological sponding to a black body at a thermal temperature
Survey before being appointed professor of geo- of 3.5 K. The explanation given by Dicke and P J E
physics at Toronto in 1946, a post he held until his Peebles (1935“ ) was that the radiation is the
retirement in 1974. Although initially a staunch residual radiation from the ˜Big Bang™ at the uni-
opponent of continental drift, Wilson is now verse™s creation, which has been cooled to 3.5 K by
known for his notable contributions to plate tec- the expansion of the universe. This cosmic back-
tonics. In 1963 he provided some of the earliest sup- ground radiation had been predicted to exist by
port for the sea-floor spreading hypothesis of H H Gamow, Alpher and R C Herman (1914“97) in 1948.
Hess by pointing out that the age of islands on Wilson and Penzias together won half the 1978
either side of mid-ocean ridges increases with their Nobel Prize for physics for their work.
Windaus, Adolf (1876“1959) German organic
distance from the ridge. He subsequently suggested
that there exist ˜hot spots™ in the mantle where chemist: a major contributor to steroid chemistry.
plumes of mantle material rise due to convection Windaus first studied medicine, but was
currents, and that as the lithospheric plates pass attracted into organic chemistry by attending lec-
over them volcanic islands are formed. His other tures by Emil Fischer. He became professor at
important contribution has been the concept of the Göttingen in 1915, and remained there. From 1901,
transform fault, introduced in 1965, which occurs when he was 25, he worked (like Fischer) with nat-
where continental plates slide past one another ural products and became the dominant figure in
380
Wöhler, Friedrich




Eurasian
Plate
North
American
Plate
Philippine
Caribbean
Plate
Plate
Hellenic Iranian
Plate Pacific
Plate
Plate
Arabian
Plate
Cocos
Plate
African
South
Plate
American
Nazca Plate
Plate Indo-Australian
Plate


Scotia
Plate Divergent plate
Convergent plate


Plate tectonics “ major lithospheric plates

unravelling the intricate chemistry of the steroid Young Wöhler was not very successful as a school-
group. His successes here included, especially, his boy; his passion for chemistry distracted him from
work on the vitamin D group. He also worked on vit- all else. He graduated in medicine and at once
amin B1 and discovered the biogenic amine hista- moved to chemistry by joining Berzelius for a year.
mine, a key compound in allergy. He won the Nobel On his return to Germany he began teaching chem-
Prize for chemistry in 1928. istry, which was to fill his life; he was professor
Withering, William (1741“99) British physician: at Göttingen from 1836 until his death. Wöhler
made classic study of the medicinal use of digitalis. discovered the cyanates, and in 1828 he showed
A graduate of Edinburgh, Withering practised in that ammonium cyanate when heated gave urea:
NH4CNO ’ CO(NH2)2. Urea is a typical animal prod-
Stafford and then moved to Birmingham at the sug-
gestion of Erasmus Darwin of Lichfield (grandfather uct, so that this reaction could be interpreted as
of Charles Darwin). He was a member of the Lunar marking the end of the idea of a ˜vital force™ essen-
Society, a group of Midland scientists including tial for the chemistry of life. In fact several odd
Priestley, J Wedgwood (1730“95) and M Boulton
(1728“1809), who met monthly at the full moon (to
assist their homegoing) and he was a keen botanist.
Finding that an extract of herbs had long been used
to treat ˜dropsy™ (oedema), Withering made a careful
study of the matter and found that the active herb
was the foxglove and that some cases of oedema
could indeed be treated effectively with foxglove
leaf extract. He gave an excellent report of this work
in his classic An Account of the Foxglove... (1785); it is
modern in style, with good case histories and
includes failures as well as successes. It was later
found that the extract contains digitalis, which
steadies and strengthens heart action and which is
still used for this.
He was also a mineralogist, and witherite (barium
carbonate, BaCO3) is named after him. He suffered
greatly from chest disease (probably tuberculosis)
and lived for years in a controlled atmosphere. His
decline inspired the epigram ˜the flower of Physick
is Withering™.
Wöhler, Friedrich [voeler] (1800“82) German
chemist: achieved a synthesis of urea and first made
many novel inorganic and organic compounds. Friedrich Wöhler
381
Wollaston, William Hyde

features confuse this. Wöhler™s cyanate was made Woodward™s career was marked throughout by
by a process which was not wholly inorganic. Also, brilliance. He went to the Massachusetts Institute
J Davy (1790“1868) had made urea in 1812 from NH3 of Technology when he was only 16, was ˜sent
and COCl2 but had not realized what he had made down™ for a year for ˜inattention to formal studies™
from these truly inorganic reactants. Syntheses by but nevertheless emerged with his PhD at 20. Soon
Kolbe and by Berthelot in the 1840s and 1850s he moved to Harvard, and remained there. He did
marked the real logical end of vitalism; but major work in most areas of organic chemistry, but
Wöhler™s work in 1828 ended it in the minds of his most striking work was in the synthesis of
many chemists. complex natural products. His successes in synthe-
In 1832 Wöhler™s young wife died and, to distract sis included quinine (1944), cholesterol and corti-
him, Liebig invited him to Giessen for some joint sone (1951), lysergic acid (the parent of the
work. This was a study of ˜oil of bitter almonds™, hallucinogen LSD) and strychnine (1954); the first
probably suggested by Wöhler; and from the oil major tranquillizer, reserpine (1956), chlorophyll
(benzaldehyde) they made the related acid, chlo- (1960) and the tetracycline antibiotics (1962). The
ride, cyanide and amide. Structure theory was yet high point was the synthesis of vitamin B12 (cyano-
to come; but the two recognized that a group of cobalamin) in 1971, after 10 years™ work in collabo-
atoms (the benzoyl group, C6H5CO) was present in ration with a team of Swiss chemists, led by
all these compounds. This was the first substantial A Eschenmoser at ETH Zurich. Woodward, fuelled
˜compound radical™ to be recognized, and this in the hundred-stage synthesis by a mixture of
recognition was the beginning of the end of a whisky, cigarettes and arrogance, died before the
period of confusion in organic chemistry. Nobel committee could consider the award to him
Wöhler first made aluminium and beryllium, of a second prize: he had been awarded one Nobel
crystalline boron and silicon, and calcium carbide, Prize in 1965.
and he saw (in 1863) the analogy between com- In each case the work was marked by the elegance
pounds of carbon and those of silicon. and ingenuity of the synthesis, in making a valu-
In his long and valuable friendship with Liebig, able and highly complicated product from simple
Wöhler displayed none of the enthusiasm Liebig starting materials, using a large number of chemi-
had for controversy. Wöhler had a lighter view; he cal steps. His methods frequently provided novel
was the writer of a skit on Dumas™s substitution general syntheses of other compounds. In 1965
theory which was published in the Annalen under he developed the Woodward“Hoffmann rules
the name S Windler. Later he remarked that he concerning the path of a large class of addition
should have given a French name such as Ch reactions.
Arlaton. He enjoyed writing and teaching even He had a remarkable memory, an unsurpassed
more than research, and probably taught about knowledge of organic chemistry and a cool wit. In
8000 students in his life. many ways modest, at conferences he sported a
Wollaston, William Hyde (1766“1828) British blue silk tie embroidered with the full formula of
chemist: discoverer of palladium and rhodium and strychnine, which he had synthesized in 50 stages,
pioneer of powder metallurgy. each well planned.
Wright, Sewall (1889“1988) US geneticist: discov-
Wollaston™s father™s family included several sci-
entists and physicians and he followed both inter- erer of genetic drift.
ests, at Cambridge and in London. However, in 1800 A graduate of Illinois and Harvard, Wright joined
he gave up his medical practice and in partnership the US Department of Agriculture in 1916, where
with S Tennant (1761“1815) made his income from he worked particularly on stock improvement.
the sale of platinum and devoted his time to work Later he taught at Chicago, Edinburgh and
in chemistry, optics and physiology. He discovered Wisconsin. In his stock improvement studies his
palladium in 1802 and announced this weirdly by aim was to find the best combination of inbreeding
anonymous notices offering it for sale; his discov- and crossbreeding to achieve this. He used guinea
ery of rhodium (also from crude platinum ore) he pigs as a convenient test animal and developed a
announced in the usual way, in 1804. Malleable mathematical scheme to describe evolutionary
platinum had not been made previously, but development. In his work on small isolated animal
Wollaston produced it by methods now basic to populations he found that some genes can be lost
powder metallurgy. Not unreasonably, he did not randomly, because the few individuals having
give details of his methods until shortly before his them may not reproduce successfully. This loss can
death. lead to new species without the normal processes
Woolaston was very inventive and wide-ranging of natural selection being involved, and is known
in his scientific work, and his lasting contributions as the Sewall Wright effect, a process of random
include a reflecting goniometer (for measuring ˜genetic drift™ which can be important in small
crystal angles), a modified sextant, an improved populations.
Wright, Wilbur (1867“1912) and Orville Wright
microscope and the discovery of the vibratory
nature of muscular action. (1871“1948) US aviators: made and flew the first
Woodward, Robert Burns (1917“79) US organic successful aeroplane.
chemist: probably the greatest deviser of organic The Wright brothers were a very remarkable pair
syntheses. indeed. Through the second half of the 19th-c a
382
Wu, Chien-Shiung




Wright Flyer of 1908 with Orville Wright at the controls: he sits facing the elevators, placed at the front of this aircraft.

number of individuals in Europe and the USA had son, the attempts of their predecessors seem inept
attempted flight with heavier-than-air devices but and those of their successors to be natural develop-
without real success, at best operating unmanned ments from the Wright brothers™ work. (See panel
models. The Wrights, sons of a non-conformist overleaf.)
Wu, Chien-Shiung (1912“97) Chinese“US physicist:
bishop in Dayton, OH, and owners of a small bicy-
cle-making firm, began to experiment in 1896. They team member of group who confirmed experimen-
recognized that control was as important as stability tally that parity is not conserved by the weak
and that systematic experimentation was needed, nuclear force.
and settled down to a programme of wind tunnel Born in Shanghai, Wu moved to the USA in 1936,
experiments on wing sections (aerofoils) and made having completed her degree in China. Under
over 1000 flights with unmanned biplane gliders Lawrence she obtained her doctorate from the
near Kitty Hawk on the North Carolina coast. One University of California at Berkeley in 1940 and
important step was their study of buzzards in 1899, took up a post at Princeton. From 1946 she taught
which made it clear to them that three-axis control at Columbia University, becoming professor of
was needed (to bank, turn, and elevate or descend) physics in 1957.
and that the bird achieved control over roll by Wu had intended to return to China after her
twisting its wings. postgraduate work in physics, but war and after-
By early 1903 they had a biplane with control wards communism stopped that. Columbia
achieved by warping (twisting) the wings in unison became her home, and she and her husband
along with a rudder, and with an elevator at the became US citizens in 1954; but she retained her
front. They devised an efficient propeller and made Chinese dress style, her Chinese name and her
a small (12 hp, ie 9 kW) petrol engine, which was preference for Chinese food.
fitted to a new biplane, driving two ˜pusher™ pro- From 1946 she became expert on beta-decay in
pellers; the craft had skids and not wheels and the radioactive atoms, the process whereby an electron
pilot lay on the lower plane. On a cold windy and a neutrino are ejected from a neutron in the
December morning in 1903 the first controlled, nucleus, leaving behind a proton.
powered and manned flights were made at Kitty In 1957 she developed her research on nuclear
Hawk, two by each brother. They made two more decay by emission of beta particles by observing
aircraft; the last, Flyer III of 1905, could make fig- that the direction of emission is closely tied to the
ures of eight and remain airborne for half an hour. direction of the spin of the emitting nucleus. The
Despite French and British enthusiasm, European critical experiments used radioactive cobalt-60,
results were poor until Wilbur visited Europe and (half-life 10.5 min) cooled close to absolute zero. In
demonstrated their success in the year they ceased a difficult experiment, she and four colleagues
to fly, 1908. They deserve great credit; in compari- showed that beta particles are not emitted in equal
383
Panel: The history of aeronautics


THE HISTORY OF AERONAUTICS pioneering aircraft flights included Lindbergh™s solo
crossing of the Atlantic; Amelia Earhart™s over the
As early as the 16th-c, Leonardo da Vinci was design- Atlantic and the Pacific oceans; Amy Johnson™s from
ing flying machines based on emulating the flapping England to Australia, and Mollison™s to South Africa
motion of birds™ wings, but the vehicle which first and India.
carried people clear of the Earth™s surface was a hot- The Second World War created a similar impetus.
air balloon constructed by the MONTGOLFIER brothers By the end of that conflict the later Marks of the
and flown on an ascent over Paris in 1783 by their vol- Spitfire, designed by Reginald Mitchell (1895“1937);
unteer friends de Rosier and d™Arlandes. In France the Hurricane, designed by Sidney Camm (1893“1966)
CHARLES was developing a hydrogen balloon (or aero- and the Messerschmitt, designed by Wilhelm
stat) at about the same time, but it was 1852 before Messerschmitt (1898“1978) and Walter Rethel, were
the practical problems of controlling direction of travel representative of the highest states of evolution of
and coping with adverse weather were overcome by piston-engined aircraft. This war also heralded the
the development of the balloon into an airship by arrival of the jet fighter; in 1939 the Heinkel HE 178,
Henri Giffard (1825“82). Early in the 20th-c Zeppelin built by Ernst Heinkel (1888“1958) became the
in Germany had military and commercial success with world™s first combat jet aircraft. It was followed less
airships, and small helium-filled versions still find use. than two years later by the Gloster E 28/39 powered by
In the intervening period, research was being con- a jet engine designed by WHITTLE.
ducted using models which would be recognized Rocket-powered aircraft had been introduced into
today as a conventional aircraft configuration and, by limited service by the Luftwaffe during the later stages
1853, SIR G CAYLEY, the father of aeronautics, had of the war, and research was continued in the USA. In
established the theory and constructed a man-carrying 1947, Charles (Chuck) Yeager (1923“ ) flew a Bell X-
glider. Also during this period (1847) John Stringfellow 1 rocket powered research aircraft to became the first
(1799“1883) and William Henson built a steam- man to fly faster than the speed of sound
(1200 km h “1/760 mph at sea level) breaking the so-
powered aircraft which, although incapable of sus-
tained flight, influenced subsequent aircraft design. called sound barrier. This marked a significant
LANGLEY also had limited success. advance in aeronautical engineering.
The development of man-carrying gliders was The considerable use of long-range bomber
pursued vigorously by Otto Lilienthal (1849“96) who, aircraft during the war led directly to the improvement
from his study of bird flight, recognized the impor- of passenger-carrying aircraft, and to the
tance of curved aerofoil sections to increase the effi- rapid growth of international air travel. By 1968 the
ciency of wing surfaces. With the continuing world™s first supersonic airliner, the Tupolev TU-144,
refinement of the internal combustion engine, had flown, followed a little later by the Anglo-French
invented in 1876 by OTTO and successfully harnessed Concorde. The latter continued in scheduled service,
to car propulsion by Karl Benz (1844“1929) in 1885, with a normal cruising speed twice that of sound.
the way was cleared for the most significant landmark Among other significant developments were Sidney
in manned, powered, controlled flight. In 1903, Camm™s Harrier, the first Vertical-Take-Off-and-
ORVILLE WRIGHT took off and flew for 12 seconds in a Landing (VTOL) aircraft successfully to enter service;
12-hp engined biplane constructed with his brother and the incorporation on some aircraft, notably the
Wilbur, in their cycle workshop, after a full programme General Aerodynamics F-111 fighter bomber and the
of experimentation. As the reliability of the structures BAC Tornado, of swing wings. This concept, first con-
and engines improved, the latter particularly through ceived by B N WALLIS, enables the angle of sweep-back
Lawrence Hargrave™s (1850“1915) radical rotary of the wings to be varied in flight, in order to optimize
engine design, so pioneers exploited the new medium. aerodynamic efficiency during the various stages of
Amongst these were Henri Farman (1874“1958), who flight.
made the first cross-country flight in 1908, and Louis With some military aircraft capable of reaching and
Bl©riot (1872“1936), who flew across the English operating on the fringes of space, the distinction
Channel the following year. between aeronautics and astronautics is becoming
The First World War provided a powerful stimulus increasingly blurred. Indeed, future developments will
to all aspects of aeronautical research and develop- probably draw on both sciences. The concept of air-
ment, and in 1919 Alcock and Brown crossed the craft taking off from normal airfields and climbing to
Atlantic in a twin-engined Vickers Vimy bomber. This achieve Earth orbit, before re-entering the atmosphere
feat was followed by flights of ever-increasing range, prior to a conventional aircraft style approach and
including the overflight of the North Pole by Richard landing, has been explored by British Aerospace in the
Byrd (1888“1957) in 1926 in an aeroplane and by Horizontal-Take-Off-and-Landing (HOTOL) project.
Roald Amundsen (1872“1928) in an airship. Later Geoff Leeming



384
Wynne-Edwards, Vero Copner

numbers when the cobalt nuclei are aligned in a halides react with sodium metal to give hydro-
magnetic field: more are emitted in the direction carbons (the Wurtz reaction): for example,
2n“C4H9Br + 2Na ’ n“C8H18 + 2NaBr.
opposite the field (and therefore opposite to the
direction of nuclear spin). The emission process, The reaction has been used to make very long-
therefore, is not identical for a mirror image chain hydrocarbons from, for example, 1-iodo-n-
system; and the physical laws do not remain pentacontane:
2C50H101I + 2Na ’ C100H202(n-hectane) + 2NaI.
unchanged under a parity change. This extraordi-
nary result had however been predicted by Yang The longest-chain non-polymeric compound
and Lee, who had deduced that the weak nuclear known by 1985 was tetraoctacontatrictane
interaction would not be identical under a parity CH3(CH2)382CH3, ie C384H770.
change. The results of this work were far-reaching Wurtz was a major supporter of both Dumas™s
and many basic assumptions in physics were called and Gerhardt™s early theories on the nature of
into question. organic compounds.
Wynne-Edwards, Vero Copner (1906“97) British
Wu then set out to confirm Feynman and Gell-
Mann™s theory of beta decay (1958), which predicted biologist: proposed animal altruism as basis for
conservation of a vector current. She confirmed population homeostasis control.
this in 1963. She also observed that electromag- An Oxford graduate, Wynne-Edwards taught at
netic radiation that is polarized is released on elec- McGill University, Montreal from 1930“46 and
tron“positron annihilation, as predicted by Dirac™s thereafter at Aberdeen. In Montreal he worked on
theory of the electron. the distribution of sea birds, making four round
Wurtz, Charles Adolphe (1817“84) French organic trips by Cunarder over the Atlantic in 1933 to see
chemist: a pioneer of organic synthesis. the changes in species with the seasons, and began
Wurtz™s father gave him the choice of studying to gather the results that were to be fully developed
theology or medicine. As he wished to be a chemist in his book Animal Dispersion in Relation to Social
Wurtz chose medicine, graduated and diverted to Behaviour (1962). He proposed that animal popula-
chemistry. He became assistant to Dumas and suc- tions use hormonal devices and social mechanisms
ceeded him as professor in the École de M©dicine. including territoriality, dominance hierarchies
He was an exuberant lecturer; and his research lab- and grouping in flocks as methods of controlling
oratory in Paris was unique in Europe in attracting population size; and that they will sacrifice their
as many able young men as the laboratories in own survival and their fertility for the good of the
German universities. His early research was on the group, whose survival depends on avoiding overuse
oxoacids of phosphorus, and he also discovered of the available resources. This view of animal
POCl3. altruism provoked vigorous discussion and research
Soon he moved to organic synthesis, where his in ethology and ecology; the book has been highly
many successes included the discovery of the first influential in its proposal for ˜population homeo-
amines, from the reaction of base with an alkyl iso- stasis™ and its ideas have been both criticized and
cyanate; in this way he made CH3NH2 and developed by others, including D L Lack (1910“73),
CH3CH2NH2. In 1855 he showed that reactive alkyl J Maynard Smith (1920“ ) and E O Wilson.




385
Y
Yalow, Rosalyn, n©e Sussman [yalow] (1921“ ) US Yang“Mills theory. This proved to be an important
nuclear physicist: developed the radioimmunoassay new departure in theories of elementary particles
method. and quantum fields.
Yanofsky, Charles [yanofskee] (1925“ ) US geneti-
A physicist with a special interest in radioiso-
topes, Rosalyn Yalow turned to nuclear medicine cist: experimentally verified the hypothesis that
and from 1972 was Senior Medical Investigator the DNA base sequence codes for protein synthesis.
for the Veterans Administration. Working with A graduate in chemistry from New York who
S A Berson (1918“72) in a New York hospital, she went on to work in microbiology at Yale, Yanofsky
developed from the 1950s the method of radioim- afterwards worked at Yale and Stanford on gene
munoassay to detect and measure peptide hor- mutations. His best-known work was his demon-
mones (such as insulin) in the blood. The method stration of the validity of Crick and Watson™s
has proved of great value both in locating the suggestion of 1953 that the sequence of bases in
origin of hormones in the body, and in clinical diag- the genetic material DNA determines the order of
nosis and treatment of a variety of diseases and the amino acids that make up proteins, including
male and female infertility. Extension of the of course the enzymes critical to living systems.
method in the UK has led to better control of Yanofsky secured his evidence on this by ingenious
digoxin therapy in heart disease and diagnosis of experimentation using mutant strains of a bac-
neural crest disease (eg spina bifida) in the fetus. terium; these were isolated and the positions of the
The method can be used to measure very small mutations in the gene were mapped. Likewise, the
amounts (10 “12 g) of any substance for which an amino acid sequences were determined in the vari-
antibody can be made. Its value in diagnosis and in ous mutant forms of the enzyme produced by these
the control of medication is immense. strains. It could then be shown that the changes in
Rosalyn Sussman had been a forthright child and amino acid sequences correspond with the mutant
her attempts, as a female and Jewish New Yorker, to sites on the genetic map, in accord with the theory.
Young, James (1811“83) British chemist: a pioneer
enter her chosen career before the Second World
War did not soften her. Experience as a physicist in petroleum technologist.
the Veterans Hospital, dominated by medical men Young was a part-time student in Glasgow,
and service officers, made her abrasive. After attending ˜night-school™ classes in chemistry given
Berson™s death she saw that he had been assumed to by Graham; he became Graham™s assistant. From
be the creative member of their 22-year, highly 1843 he was employed in the chemical industry
effective professional partnership. Stung by this, and in 1848 he set up a small works in Derbyshire
she increased her research output in the 20 years to purify oil from a seepage, and marketed it for
before her retirement and became even more con- lighting and as a lubricant. When after 3 years the
frontational, unsoftened by her Nobel Prize in 1977.
Yang, Chen Ning (1922“ ) Chinese“US physicist:
showed that parity is not conserved by the weak
nuclear force.
Yang, the son of a professor of mathematics,
received his college education in Kunming in China.
Taking up a fellowship for travel and research in
America he completed a PhD under Teller at
Chicago. He joined the Institute for Advanced Study
at Princeton in 1949. He became director of the
Institute for Theoretical Physics at the State
University of New York, Stony Brook in 1966.
It is Yang™s work in collaboration with Lee which
is justly celebrated as a turning point in the devel-
opment of theoretical physics: they showed that
the law of conservation of parity (ie that physical
laws are unaltered in mirror-image systems) does
not hold for the weak nuclear interactions (1956).
The prediction was confirmed by Wu™s thorough
experimental study and quickly led to the award of
a Nobel Prize for physics to Yang and Lee (1957).
Yang is also noted for his development of a non-
Abelian gauge theory with R L Mills (1924“ ), the Chen Ning Yang
386
Yukawa, Hideki

seepage was exhausted he moved to West Lothian ultimately revealed the ancient Egyptian system of
in Scotland and began to extract oil from oil shale writing, although at the time others were given more
deposits by distillation. He founded the Scottish oil credit for this: in part because his work on it was
shale industry and was one of the first to apply published anonymously, as the entry on Egypt in a
chemical methods to oil handling. supplement to the Encyclopaedia Britannica for 1819.
Yukawa, Hideki (1907“81) Japanese physicist: first
His other ventures included a measurement of
the speed of light by Fizeau™s method; and he gave described the strong nuclear force and predicted
financial support for the explorations of David the pi-meson (pion).
Livingstone (1813“73), who had been a fellow stu- Yukawa studied at Kyoto University and took his
dent and friend in Glasgow. degree there in 1929. He moved to Osaka University
Young, Thomas (1773“1829) British physiologist, to take his doctorate but returned to Kyoto for the
physicist and Egyptologist: established the wave remainder of his career, becoming professor of the-
theory of light. oretical physics in 1939.
Young surely had one of the most acute minds of When he was 27, Yukawa developed his theory of
his century, but his diversity of interests and his nuclear forces. In 1932 Chadwick had discovered
tendency to move to new ones rather than consoli- the neutron; Yukawa proposed a strong short-range
date his ideas, caused credit for some of them to force between protons or neutrons, which over-
go to others. His father was a banker, and for came electrical repulsion between the protons in
unknown reasons the boy lived largely with his the nucleus without influencing the electrons in
grandfather. He was a precocious child who could the atom. This nuclear ˜exchange™ force involves
read at the age of 2; he had a good knowledge of five the exchange of a particle between the nucleons
languages at 13 and of eight more oriental lan- (nuclear constituents) and from the short range of
the force (less than 10“12 m) Yukawa inferred that
guages at 14. At this time a young schoolmaster
also introduced him to telescope-making. its mass was about 200 times that of an electron.
In 1792 he began to study medicine, intending to In 1936 C D Anderson discovered a particle of
follow a friendly and prosperous uncle into his the correct mass and called it the mu-meson
London practice, and in his first year as a medical (now, muon); but it did not interact with nucleons
student in London he published on the physics of the sufficiently strongly to correspond with Yukawa™s
eye. By neat experiments he showed that accom- prediction. In 1947 Powell and his co-workers dis-
modation (change of focus) is a result of change in covered another meson (the pi-meson, now pion) in
the curvature of the lens; at the same time he cosmic rays which did correspond with Yukawa™s
described and measured astigmatism and in 1801 proposed particle and so established his theory of
he devised his three-colour theory of human colour the strong nuclear force. During the next 10 years
vision. He continued as a medical student, with a many types of pion and muon were discovered,
full social life, in Edinburgh, Göttingen and most with short lifetimes. They are now considered
Cambridge, and in 1799 set up a practice in London. (as are protons and neutrons) to be composed of
He was not very successful as a physician, perhaps quarks; and the forces in nuclei to be due to inter-
because (as a friend said) his mind was usually on actions between quarks and gluons.
other matters, and he was not a success as a lec- Yukawa successfully predicted (in 1936) that
turer at the Royal Institution. During these lec- nuclei may absorb one of the innermost electrons
tures, when discussing Hooke™s Law in 1802, he (in the 1 K shell) and such K capture by a nucleus
gave physical meaning to the constant in that law, was soon observed. He was the first Japanese to be
which has come to be named as Young™s modulus, awarded a Nobel Prize, in 1949.
E, defined as the ratio stress/strain; here stress is the
force per unit area of cross section of a material,
which produces a strain measured as (change in
length)/(original length). E is a measure of a mater-
ial™s resistance to change in length, and an average
value for natural rubber would be 1 — 106 Nm “2
while for a mild steel E = 2 — 1011 Nm“2.
But his major work was on the wave theory of light,
which Newton had thought to be corpuscular and
Huygens wave-like. Young argued in 1800“04 in
favour of the wave theory and supported this by clear
and detailed accounts of elegant experiments on
interference due to superposition of the waves. The
current view entirely supports Young™s interpreta-
tion of these effects, while also using a ˜corpuscular™
explanation in terms of photons and quantum
theory for such results as photoelectric emission.
From 1814 Young busied himself with his medical
practice and with Egyptology, where his major con-
tributions to the interpretation of the Rosetta Stone Hideki Yukawa
387
Z
Zeeman, Pieter [zayman] (1865“1943) Dutch physi- Imperial Historian. It was a bronze device almost
cist: discovered the splitting of spectral lines by 2 m in diameter, containing a mechanism of pendu-
magnetic fields. lums and levers, with eight dragon figures arranged
Zeeman™s experiment of 1896 proved to be an around its circumference. Strong seismic tremors
early crucial link between light and magnetism, caused a metal ball to be released from the mouth
which also gave further identification of the elec- of the dragon facing the direction of the shock wave.
tron and a basis on which to test the quantum It is known that the device registered an earthquake
mechanical theories of atomic structure. It was per- in Gansu Province in 138.
Zinder, Norton David (1928“ ) US geneticist: dis-
formed soon after Zeeman had graduated at Leiden
(under Lorentz) and had become a Privatdozent at covered bacterial transduction.
Amsterdam. He first observed that, when a mag- A graduate of Columbia University, New York,
netic field was applied to sodium or lithium flames, Zinder did graduate work with Lederberg and was
the lines in the emission spectrum of the flame professor of genetics at Rockefeller University from
were apparently broadened; and this on inspection 1964. Lederberg was the first to observe sexual
was due to splitting of the lines into two or three. union (conjugation) in a bacterium (Escherichia coli);
Zeeman™s observation agreed with results from Zinder looked for it in Salmonella. He soon devised a
Lorentz™s classical theory of light as being due to valuable new technique for isolating mutants of
vibrating electrons in atoms. this bacterium, but his attempt to observe conjuga-
The normal Zeeman effect is shown when a spec- tion led him instead to the discovery of bacterial
tral line splits into two with a strong magnetic field transduction. This is the transfer, by a phage parti-
applied parallel to the light path or into three if the cle, of genetic material from one bacterium to
field is perpendicular. The old quantum theory another; the discovery led to new knowledge of the
and Bohr™s model of the atom could explain this. location and behaviour of bacterial genes.
Zsigmondy, Richard Adolf [zhigmondee] (1865“
However, in general, atoms show the anomalous
Zeeman effect, which involves splitting into several 1929) Austrian colloid chemist; the inventor of the
closely spaced lines. The explanation of this required ultramicroscope.
the full quantum mechanics (of 1925) and the After studying chemistry and physics Zsigmondy
concept of electron spin, due to Uhlenbeck and joined the Schott glassworks at Jena; it was through
Goudsmit (1926). Zeeman and Lorentz shared the his interest in coloured glass that his work on col-
1902 Nobel Prize for physics for their work on the loids began, and this was continued through his
magneto-optical properties of atoms. career as a professor at Göttingen. In 1903 he made
Faraday had experimented in 1862 on the appli- an ˜ultramicroscope™ in which the sample is strongly
cation of a magnetic field to emission spectra, but lit from one side against a dark background. This
failed to find an effect; Zeeman succeeded and allowed colloid particles to be seen as points of
the explanation of his results was a major step for light, even if they were smaller than the resolving
theoretical physics. power of the microscope. Such studies were of great
The Zeeman effect has been used (first by Hale in value before the introduction of the ultracentrifuge
1908) to examine the Sun™s magnetic field and and the electron microscope. Zsigmondy examined
(with much greater difficulty) that of other stars. many colloidal solutions (especially gold sols),
Zhang Heng (78“139) Chinese astronomer and geo- deduced particle sizes and concluded that the parti-
physicist: invented the earthquake seismograph. cles are kept apart by electrostatic charge. Colloidal
Zhang was born in Nanyang, Henan Province, solutions are of great importance in biochemistry.
during the Han Dynasty. He was Imperial Historian His pioneer studies did much to advance under-
and official astronomer. standing of sols, gels, smokes, fogs and foams, and
Zhang recognized that the source of the Moon™s he was awarded a Nobel Prize in 1925 for his work.
Zu Chongzhi (429“500) Chinese mathematician and
illumination was sunlight and that lunar eclipses
astronomer: improved the accuracy of π and mea-
were caused by the Earth™s shadow falling upon it.
He devised a water-driven celestial globe, which sured the length of the year.
Zu computed π to be 355/113 (about 3.1415929), a
revolved in correspondence with the diurnal
motion of the celestial sphere. In mathematics, he value not bettered until 1000 years later by al-Kashi
calculated π as 365/116 (about 3.1466), a substantial (d. c.1430) and Viète, and also gave 22/7 as a simpler
improvement on the hitherto accepted Chinese value for calculations where less accuracy was suf-
value of 3. Perhaps his best remembered contribu- ficient. In astronomy, he measured the length of
tion, however, was to geophysics: in 132 he invented the year to be 365.2429 days, by extensive observa-
an early seismograph. This was to help him locate tions of the lengths of shadows around the winter
and record earthquakes, one of his official duties as solstice, an improvement over contemporary values.
388
Zworykin, Vladimir

Zworykin, Vladimir (Kosma) [tsvorikin] (1889“ image from a screen by dividing it into many insu-
1982) Russian“US physicist: invented the elec- lated photoelectric cells, which held a charge propor-
tronic-scanning television camera. tional to the light falling on them. An electron beam
Soon after graduating in engineering from St scanning the screen discharged the cells in turn,
Petersburg Institute of Technology, Zworykin spent giving an electrical signal.
the First World War serving as a radio officer in the Zworykin then took a cathode-ray tube (invented
Russian army. One of his teachers in St Petersburg by Braun in 1897), which could produce focused
was B Rosing, who took out the first patent for a spots on its fluorescent screen using electric and
television system in 1907; it used a cathode-ray magnetic fields. As the beam scanned the screen
tube as its receiver. After Russia™s collapse into the intensity of the spot varied according to the
revolution in 1917 Zworykin emigrated to America electrical signal and so could reproduce the images
in 1919 and joined the Westinghouse Electric from his first device, so that he had a television
Corporation. His career developed as he gained a transmitting and receiving system. By 1929 the
doctorate (1926) and moved to a post with the Radio camera had been developed to the point of prac-
Corporation of America (1929). tical use, and it displaced the mechanical system
While at Westinghouse in 1923 he reproduced an developed by Baird.




389
Chronology



This lists a number of major events in science, and notes also (in bold type) some other events of
historical interest. Titles of important scientific books are given in italics; in general these surveyed
earlier work in their field and also initiated fruitful advances.
c.550 bc Anaximander proposes Earth is poised Giordano Bruno burned for heresy by
1600
in space. the Inquisition: he had supported
c.450 bc Empedocles proposes four-element Copernicus™s ideas, and he had sug-
theory of matter. gested that other planets might circu-
c.330 bc Theophrastus founds scientific botany. late around other Suns, a concept
c.300 bc Euclid systematizes geometry. proved correct in the 1990s.
c.250 bc Archimedes founds mechanics and De magnete (Gilbert) surveys magnetism,
hydrostatics. and proposes that Earth is a giant
c.200 bc On Conic Sections (Apollonius). magnet.
30 or 33 Christ is crucified. Fabrizio describes valves in human
1603
Romans begin conquest of Britain. veins, but is unclear on their function.
43
Zhang Heng invents seismograph. English settlements in Virginia.
132 1607
c.825 Al-Khwarizmi gives general solution for Lippershey and Jansen make first useful
1608
telescope (3 —) and offer it for military
quadratic equation.
c.1000 Alhazen™s work in optics. use.
c.1350 Black Death devastates Europe. Kepler publishes his first two laws of
1609
Gutenberg and Koster independently planetary motion.
1440
introduce printing by movable type. Lippershey and Jansen make early com-
Columbus lands in West Indies and pound microscope.
1498
South America. Galileo publishes his astronomical
1610
Luther™s 95 theses begin the observations made with a telescope
1517
(30 —).
Protestant Reformation in Germany.
1519“22 Magellan™s ship circumnavigates the Santorio describes first scientific study
1614
world; Cortez conquers Mexico. of human metabolism.
Copernicus publishes heliocentric Snel discovers law of refraction.
1543 1621
system in his De revolutionibus... Logarithmical Arithmetic (Briggs) eases
1624
Vesalius establishes anatomy by his computation.
De fabrica corporis humani. De motu cordis (Harvey) describes
1628
De re metallica (Agricola) surveys mining circulation of the blood.
1556
and metallurgy. Large-scale emigration from England
1630
Mercator publishes a map of to Massachusetts begins.
1569
the world based on his new Galileo publishes his Dialogo...
1632
projection. supporting Copernicus™s heliocentric
Brahe observes supernova (Tycho™s star). system.
1572
T Digges proposes that stars are at Galileo is charged with heresy, and
1576 1633
varying distances, and that universe is recants.
infinite. Descartes introduces analytic
1637
Drake, circumnavigating the world, geometry.
1579
lands in California. Civil War begins in England.
1642
Spanish Armada is defeated. Galileo dies, Newton is born.
1588

390
Chronology

Torricelli constructs mercury Amontons observes relation of gas
1644 1699
barometer. pressure to temperature.
Pascal experiments with barometers, c.1701 Halley produces magnetic map of world.
1646
and later shows that air pressure drops First English daily newspaper (Daily
1702
Courant) .
with rising altitude.
Guericke makes an effective air-pump Opticks (Newton) surveys nature and
1650 1704
after 15 years™ work. behaviour of light. An appendix pro-
Harvey publishes on embryology: poses that all matter is composed of
1651
ahead of his time, he claims that ˜all small, hard particles (atoms).
creatures come from an egg™. First American newspaper (Weekly
Review) published in Boston.
Probability theory initiated by Pascal
1654
and Fermat in response to a request Halley publishes book on comets, and
1705
from gaming friends. correctly predicts a bright comet for
Guericke™s hemispheres demonstrate 1758 with a period of about 76 years
pressure of atmosphere. (Halley™s comet).
Swammerdam sees red blood cells in Union between England and Scotland
1658 1707
frogs. creates the kingdom of Great Britain.
Boyle finds law relating pressure to Vegetable Staticks (Hales) surveys plant
1660 1727
volume for a gas. physiology.
Royal Society is founded. Bradley measures speed of light
1729
The Sceptical Chymist (Boyle) defines Gray publishes his work on
1661
chemical elements. electricity.
Evelyn publishes on air pollution: his Hales™s Haemastaticks surveys his work
1733
proposed remedies are not acted upon. on blood circulation and pressure in
Malpighi describes animal capillaries. animals.
Micrographia (Hooke) advances Systema naturae¦ (Linnaeus) classifies
1665 1735
microscopy, and also discusses plants effectively.
meteorological instruments. Hadley™s work on trade winds.
Great Plague sends Newton home from D Bernoulli™s Hydrodynamica initiates
1738
Cambridge. In 1665“6 he devises the the science of fluid flow.
binomial theorem, the calculus, and Maria Agnesi publishes her widely-used
1748
the theory of gravitation. and comprehensive textbook on math-
Newton makes the first reflecting ematics.
1668
telescope. Franklin uses kite to show electrical
1752
Bartholin describes double refraction nature of lightning.
1669
by calcite. Desmarest argues that a land bridge
Steno publishes ideas on mountain- between England and France must
building, strata and fossils. have existed at one time.
Leeuwenhoek studies red blood cells. A Treatise on the Scurvy (Lind) shows
1673 1753
Roemer shows light has finite speed, value of citrus fruits in its prevention
1675
and calculates that it takes 11 minutes and treatment.
to cross the Earth™s orbit. Joseph Black studies chemistry of
1756
Brand discovers phosphorus. carbon dioxide and lime.
1677
Huygens expounds wave theory of Monro distinguishes lymphatic and
1678 1757
light. circulatory systems.
Principia mathematica (Newton) creates Dolland patents his achromatic lens.
1687
celestial mechanics. c.1763 Black recognizes ˜latent heat™.
Camerarius experiments on sexuality Spallanzani disproves theory of
1694 1767
in plants. spontaneous generation.

391
Chronology

Lambert proves π and e to be irrational. its velocity increases and the pressure
1768
Cook circumnavigates New Zealand. falls.
Titius proposes Bode™s law. Cavendish weighs the Earth.
1772 1798
Boston Tea Party. Rumford publishes his work on the
1773
Harrison is awarded the balance of the conversion of work into heat.
prize for his chronometer, having Volta makes cell for supply of electric
1800
worked on it since 1728. current.
Priestley discovers oxygen, but misin- Nicolson and Carlisle show that water
1774
terprets his results. is decomposed by electricity to give
American Declaration of hydrogen and oxygen.
1776
Independence. Davy discovers N2O and suggests its use
Ingenhousz™s work on photosynthesis. as an anaesthetic (not used until 1844).
1779
Iron bridge built across the R Severn Leslie devises wet and dry bulb
at Coalbrookdale, England. hygrometer.
Herschel discovers Uranus. F W Herschel discovers infrared
1781
American victory over British troops radiation.
at Yorktown. Dalton publishes law of partial
1801
First manned hot air balloon flight pressures.
1783
(at Versailles). Piazzi discovers first asteroid (Ceres).
F W Herschel shows that the entire Lamarck argues that species change
solar system is moving in space relative with time by inheritance of alterations
to the stars. made by their adjustment to their envi-
Cavendish publishes his work on the ronment.
1784
synthesis of water from hydrogen and Haüy publishes his studies on crystal-
oxygen. lography and mineralogy.
Michell deduces possibility of black Arithmetical Researches (Gauss).
holes in universe. Ritter discovers ultraviolet radiation.
F W Herschel makes a systematic study Political Union between Great Britain
1785
of the likely shape of our Galaxy (the and Ireland.
Milky Way). Young demonstrates interference of
1803
Charles formulates law on gas light, supporting wave theory of
1787
temperature“pressure relation. light.
Penal settlements established in Dalton publishes law of multiple
1788 1804
Australia. proportions.
Elementary Treatise on Chemistry Beaufort proposes his wind scale.
1789 1806
(Lavoisier) initiates chemical Argand devises diagram for represent-
revolution. ing complex numbers.
Fall of the Bastille; French C Bell shows that nerves convey either
1807
Revolution. sensory or motor stimuli but not both.
Galvani publishes on ˜animal electric- Young proposes that heat is probably a
1791
ity™, which he has studied for 11 years. wave vibration, and not a material sub-
Theory of the Earth (Hutton) begins much stance.
1795
of modern geology. Davy makes sodium and potassium by
The metric system officially adopted in electrolysis.
France. W Henry publishes law discovered by
1808
Jenner experiments on vaccination him in 1803 on solubility of gases in
1796
against smallpox. liquids.
Venturi observes that when a fluid Dalton publishes his atomic theory,
1797
(water) passes through a constriction, first offered by him in 1803.

392
Chronology

Gay Lussac™s law of combining Ampère begins work on electro-
volumes of gases. dynamics.
Davy uses electrolysis to isolate Ba, Sr, Mitscherlich publishes law of
Ca, Mg. isomorphism.
George Cayley begins to publish his Seebeck discovers thermoelectric
1809 1822
experiments, continued over the next effect.
30 years, which will found the theory of Fourier suggests using mass, length
aerodynamics. and time as fundamental dimensions.
Davy shows that chlorine is a chemical Olbers™s paradox postulated.
1810
element and not a compound. Chevreul deduces nature of fats, and
Avogadro proposes law on atomicity of begins use of melting point to check
1811
gases. purity of a solid substance.
C Bell™s New Idea of the Anatomy of Macintosh exploits J Syme™s rubberiz-
the Brain proposes that different ing of cotton fabric.
parts of the brain have different Reflections on the Motive Power of Fire
1824
functions. (Carnot) initiates thermodynamics.
Cuvier develops his studies on fossil Flourens™s work on central nervous
1812
bones, leading to vertebrate system.
palaeontology. Pr©vost and Dumas argue that sperm is
Dulong discovers NCl3 and loses an eye necessary for fertilization.
1813
and two fingers in the process. Daguerre produces ˜daguerrotype™
Fraunhofer observes dark lines in Sun™s photographic plates, and announces
1814
spectrum. improved version in 1839.
Guy Lussac suggests (correctly) that the First steam locomotive railway, 28 km
1825
arrangement of atoms in a compound long, opened in County Durham,
may be important. England for freight and passengers.
Biot shows that optical activity is a Faraday discovers benzene.
1815
molecular property. Ohm begins work which leads to Ohm™s
Napoleon defeated at Waterloo. Law in 1827.
Gay Lussac discovers cyanogen and Balard discovers bromine.
studies cyano compounds. Von Baer begins study of mammalian
1826
W Smith publishes his stratigraphic ovum and embryo.
map of Britain. Lobachevsky introduces non-Euclidean
La«nnec invents stethoscope. geometry.
1816
Sophie Germain creates mathematical Ampère™s Law in electromagnetism.
1827
theory of elastic surfaces. Ohm establishes law of electrical
W Smith shows value of fossils in resistance.
1817
stratigraphy. Brown observes movement of pollen
Berzelius publishes his table of grains under microscope.
1818
relative atomic weights. Friction matches introduced.
Bichat founds histopathology. Wöhler synthesizes urea.
1828
Dulong and Petit find relation between Caroline Herschel publishes catalogue
1819
specific heat capacity and of star clusters and nebulae.
relative atomic mass. Berzelius lists ˜atomic weights™ of 28
Fresnel and Arago deduce that light elements.
vibrates transversely to its direction of Nicol describes his polarizing prism.
1829
forward movement. Quetelet analyses Belgian census statis-
Oersted shows that a current in a wire tically, and correlates deaths with age,
1820
induces a magnetic field around it. sex, occupation and economic status.

393
Chronology

Babbage writes on scientific frauds; A Cayley invents n-dimensional
˜cooking™, ˜trimming™ and forging geometry.
results. Joule measures mechanical equivalent
Principles of Geology (Lyell) surveys geo- of heat.
1830
logical changes, seen as due to ordinary British Algae: Cyanotype Impressions (Anna
effects acting over a long time, rather Atkins): first scientific book illustrated
than ˜catastrophes™. with photographs.
Screw steamer Great Britain crosses
Faraday begins work on electricity and
independently of J Henry discovers Atlantic.
electromagnetic induction. Faraday classifies magnetic materials
1845
Darwin begins 5-year voyage on HMS and discovers rotation of polarized
1831
Beagle. light by a magnetic field.
Babbage makes his ˜difference engine™ Neptune discovered by Galle.
1833 1846
for computing. Mallet theorizes on earthquakes and
Ada King, Countess of Lovelace writes Dana on volcanoes.
first computer program for Babbage™s Marx and Engels publish the
1848
Communist Manifesto.
more advanced ˜analytical engine™.
Beaumont concludes that digestion is Joule estimates speed of gas molecules
purely chemical. from kinetic theory.
Wheatstone measures speed of Addison associates a disease with
1834 1849
electricity in lengths of wire. failure of the adrenal gland.
Geological Survey of UK established. Snow asserts (correctly) that cholera is
1835
Morse makes model electric transmitted by polluted water.
telegraph. Fizeau makes accurate measurement of
Marc Dax concludes that the brain is speed of light.
1836
asymmetric, eg the left hemisphere Clausius develops thermodynamics,
1850
controls speech. using ˜first and second laws™ as key
Magnus analyses blood gases and finds concepts, ideas further developed by
1837
more oxygen in arterial blood than in W Thomson in 1851.
venous blood, implying that respira- Great Exhibition in London.
1851
tion occurs in tissues. Hofmeister unifies ideas on plant
Remak shows that nerves are not reproduction.
1838
hollow tubes. Helmholtz invents ophthalmoscope.
Bessel measures first stellar distance. Kelvin proposes an ˜absolute™
Schwann, and Schleiden, expound cell temperature scale, later known by
1839
theory in biology. his name.
Postage stamps introduced in UK. Frankland introduces idea of chemical
1840 1852
Henle offers essentially correct views valence.
on the nature and causes of infectious Foucault demonstrates rotation of
diseases. Earth by use of pendulum.
Agassiz postulates ice ages. Pringsheim confirms sexuality of algae.
1855
New Zealand colonized. Logan and Hunt describe geology of
Doppler discovers effect named after Canada.
1842
him. Bessemer patents steel-making by
1856
W and H Rogers describe the structure ˜converter™.
and probable origin of the Appalachian Ferrel explains atmospheric circulation
Mountains. using Coriolis force.
Schwabe finds 11-year sunspot cycle. Buys Ballot announces law on rotation
1843 1857
Electric telegraph introduced. of cyclones and anti-cyclones.

394
Chronology

Kekul©™s theory of organic molecular Kekul© proposes ring structure for
1858
structure. benzene.
Virchow, in his book Cellularpathologie, End of American Civil War.
argues that all disease occurs in the Loschmidt calculates Avogadro
constant as ≈ 6 — 1023.
cells.
Wallace sends Darwin his ideas on the Elizabeth Garrett completes a legally
origin of species, which spurs Darwin qualifying medical course in UK.
to publish his own similar ideas. Transatlantic telegraph cable begins
1866
Sorby shows how microscopy allows operation.
deductions on rock formation. Lister shows value of antisepsis in
1867
The Origin of Species (Darwin) argues that surgery, used by him from 1865.
1859
much observation of plant and animal Mendelayev describes periodic table.
1868
species is consistent with a belief in Marsh founds American palaeontology.
their evolution, and with natural selec- University of Paris (Sorbonne) admits
tion as the cause of it. women.
Bunsen and Kirchhoff introduce spec- T Andrews discovers critical state for
1869
trum analysis. gases.
Drake drills oil-well in Pennsylvania. Suez Canal opened.
British Medical Register created; it First transcontinental railway
includes Elizabeth Blackwell. opened, in USA.
Lincoln becomes president of the USA. Franco-Prussian War.
1860 1870
Selective staining, and use of micro- The Descent of Man (Darwin) surveys
1871
tomes, begin to improve microscopy in possible paths of human evolution,
biology. regarding man as an evolved animal.
Cannizzaro clarifies relation of atoms 1872 Cornell becomes first university in
to molecules. Eastern USA to admit women. (West of
Gegenbaur shows that all vertebrates™ the Mississippi most state universities
1861
eggs are single cells. were co-ed from the start.)
Crookes discovers thallium. Perrault deduces that rain and snow
1874
American Civil War begins. provide supply for river water, follow-
Pasteur ends debate on spontaneous ing close study of Upper Seine.
generation. Van ™t Hoff advances stereochemistry.
Alvan Clark and his son discover Braun uses semiconductors as rectifiers.
1862
Sirius B. Hertwig first observes union of sperm
1875
Sachs shows that plant starch is a prod- and ovum (in sea-urchin).
uct of photosynthesis, derived from Draper photographs solar spectrum.
1876
atmospheric CO2. Hertwig shows that genetic material
Angström discovers hydrogen in reaches offspring from both parents.
Sun. A G Bell patents telephone.
Waldeyer describes cancer in modern Manson shows insect vectors involved
1863 1877
terms. in some diseases.
Tyndall discusses greenhouse effect of First British university accepts women
Earth™s atmosphere. medical students (King™s and Queen™s
Maxwell derives equations on electro- College of Physicians, Dublin).
1864
magnetism, linking magnetism, elec- Cailletet liquifies common gases.
1878
tricity and optics. University of London opens its degree
Clausius introduces concept of entropy. courses to women.
1865
Mendel publishes on heredity, and is First electric railway exhibited, in
1879
largely ignored. Berlin.

395
Chronology

Cambridge University admits women Buchner shows that intact yeast cells
1881 1897
to examinations, but not to degrees. not needed for fermentation.
Mechnikov describes phagocytosis. J J Thomson studies electrons.
1882
Ants, Bees and Wasps (Lubbock). Curies discover activity of radium, and
1898
Flemming describes mitosis. isolate a sample in 1902.
First generating station supplying First widely used synthetic drug
1899
electricity to private consumers opens (Aspirin) marketed by Bayer AG.
in New York. J A Fleming invents thermionic diode.
1900
University of London awards first Planck initiates quantum theory.
1883
medical degrees to women. Mendel™s work on heredity
Balmer finds sequence in hydrogen rediscovered.
1884
spectra (Balmer series). Pearson introduces chi-square test in
Oxford University admits women to statistics.
examinations, but not to degrees. Bordet experiments on complement
1901
Galton demonstrates individuality of fixation.
1885
human fingerprints. Marconi transmits signal (˜SOS™) by
Moissan isolates fluorine. radio across the Atlantic.
1886
Tesla makes first AC motor. Landsteiner describes ABO blood
1887 1902
Michelson and Morley show that ether system.
is probably non-existent. Richet discovers anaphylaxis.
Hertz discovers radio waves. Heaviside and Kennelly find radio-
1888
Nansen explores Greenland icecap. reflecting layer in atmosphere.
Behring and Ehrlich develop Bateson applies Mendel™s laws to ani-
1890
diphtheria antitoxin. mals as well as plants.
Hollerith punch card system used to Einthoven describes use of ECG.
1903
process US census. Wright brothers make first manned,
Dewar improves insulating flask, powered and controlled flight.
thereafter widely used in laboratories Rutherford and Soddy propose that
and on picnics. radioactivity is due to atomic disinte-
London Underground railway opens. gration, an idea widely ridiculed.
Weismann observes meiosis, and Boveri, Sutton and others argue that
1892
proposes germ-plasm theory of ˜hereditary factors™ (later to be
heredity. called genes) are located on the
Nansen begins Fram expedition to chromosomes.
1893
Arctic. Blackman demonstrates limiting
1905
Rayleigh and Ramsay discover first factors in plant growth.
1894
noble gas, argon. Einstein™s theory of special relativity;
and E = mc2 relation.
Röntgen discovers X-rays.
1895
Diesel invents compression-ignition Oldham deduces existence of Earth™s
1906
engine. core.
Becquerel discovers radioactivity (of Tswett uses chromatography.
1896
uranium). Hopkins deduces existence of
Arrhenius calculates result of vitamins.
additional CO2 on greenhouse effect. Nernst states third law of thermody-
Birkeland theorizes on origin of aurora. namics.
Zeeman effect links light with magnet- Integrative Action of the Nervous System
ism experimentally. (Sherrington).
Boltzmann™s equation relates entropy Brunhes discovers past geomagnetic
to probability. reversal in rocks.

396
Chronology

De Forest patents triode valve (radio hydrogen, based on his ˜Bohr atom™.
1907
tube). Moseley shows meaning of atomic
Ross Harrison devises new tissue number.
culture method using frog nerve cells. J J Abel isolates amino acids from blood.
1914
Pavlov publishes his work on Russell publishes H“R diagram.
conditioned reflexes. World War First begins.
Inborn Errors of Metabolism (Garrod). Adams identifies first white dwarf star.
1908 1915
Kamerlingh-Onnes liquefies helium. Twort discovers bacteriophage.
First Model T automobiles made by Schwarzchilde proposes possible exis-
1916
Ford Motor Co. tence of ˜singularities™ (˜black holes™).
Ehrlich begins modern chemotherapy Bolshevic Revolution in Russia.
1909 1917
with Salvarsan. Eddington describes bending of light
1919
Morgan begins using Drosophila in by Sun, as predicted by Einstein™s
genetics. general relativity theory of 1916.
C D Walcott discovers fossils of strange Adrian uses cathode ray tube to study
soft-bodied animals in the Burgess nerve impulses.
Shale of British Columbia; re-studied Rutherford discovers the proton,
after the 1960s these small and weird and artificial transmutation of
animals, 530 million years old, are seen elements.
to form lines of evolution which mostly Michelson measures first stellar diame-
1920
became extinct. ter (other than the Sun™s).
Mohorovic ic describes discontinuity
˜´ Goddard develops theory of rocket
between Earth™s mantle and crust. propulsion, and launches liquid-
Bl©riot crosses English Channel by fuelled rocket in 1926.
aeroplane. Oxford University admits women to
Sörensen invents pH scale of acidity. membership and degrees.
Millikan measures charge on the Banting and Best treat diabetic patients
1910 1922
electron. with insulin.
Amundsen reaches South Pole. Carrel studies white blood cells.
1911
Morgan and Sturtevant plot first First public radio service begins (BBC).
chromosome map. Pauli states his exclusion principle.
1924
Rutherford proposes nuclear Appleton discovers radio reflecting
structure of atoms. layer in ionosphere.
Millikan measures electron charge. First demonstration of TV by Baird.
1926
C T R Wilson devises cloud chamber. H J Muller discovers biological muta-
Kamerlingh-Onnes discovers tions induced by X-rays.
superconductivity. Dirac unifies new quantum theory.
V F Hess discovers cosmic rays. The Theory of the Gene (Morgan) begins
Wegener proposes theory of modern period in genetics.
1912
continental drift. Heisenberg proposes uncertainty
1927
Von Laue shows that X-rays can be principle.
diffracted and so behave as waves, Lema®tre initiates ˜Big Bang™ theory of
and the Braggs develop the concept and origin of universe.
create X-ray crystal structure analysis. Electronic Theory of Valency (Sidgwick)
Henrietta Leavitt devises method for surveys chemical bonding, seen as due
measuring stellar distances. to electron-transfer (electrovalence) or
Slipher measures speed of rotation of electron-sharing (covalence).
planets and spiral galaxies. Alexander Fleming discovers
1928
Bohr calculates spectrum of atomic penicillin.
1913

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