




































Marcu 24, 1923] 
halogen, since the only work we can imagine one 
quantum capable of doing is to release a single electron 
from an atom. If several hundred quanta per grain 
are available, then it is clear that not one atom of 
silver per grain may be affected, but that several 
hundred atoms may be changed, and that an appreci- 
able, though very small, amount of chemical decom- 
position may be effected by the energy available. 
More important still, quantitative differences in the 
amount of latent image present in a grain become 
possible. If only one quantum per grain is available, 
a grain is either exposed or not exposed, but if energy 
corresponding to an amount of several hundred quanta 
is used, we might imagine that a grain could become 
partly exposed, so that, for example, it might be 
developable by a developer of high reduction potential 
Dr. JAMES Gow. 
HE lamented death on February 16 of Dr. James 
Gow, formerly headmaster of Westminster School, 
and author of “A Short History of Greek Mathe- 
matics,” calls for notice in Nature. Educated at 
King’s College School, Gow went to Trinity College, 
Cambridge, in 1871, and was 3rd Classic and Chan- 
cellor’s classical medallist in 1875. He was elected 
fellow of Trinity in 1876, the year in which it was 
bserved as a curiosity that the four fellows of Trinity 
then elected all had monosyllabic names and mustered 
o more than fifteen letters between them: Cox, 
icks, Lord, Gow. Three of them, including Gow, 
owed for the historic Second Trinity Boat Club, now 
extinct. 
Gow’s mind was alert, quick, and versatile; he 
could have succeeded at almost anything he undertook. 
e son of an artist, he had himself decided talent 
the same direction ; he was, as an undergraduate, 
devoted to music. But his main work was in classics, 
and even there his interests were very varied. His 
fellowship dissertation was on the origin of gram- 
tical gender ; he edited the Odes and Epodes and 
he Satires of Horace ; and he produced one of the 
most useful books ever written for schoolboys, a “‘ Com- 
panion to School Classics ’’—a pioneer work which gave 
a lead to more ambitious and bulky handbooks since 
issued from the University Presses and elsewhere. 
The “Short History of Greek Mathematics” is 
another proof of Gow’s versatility. His original in- 
tention was to write a history of the city of Alexandria. 
He contemplated a chapter in that work which should 
deal with the mathematical school from Euclid to 
Diophantus. But this project led him insensibly to 
more general mathematical topics, such as the develop- 
ment of numeral systems, Egyptian arithmetic, Greek 
result that the material accumulated became too 
extensive for a chapter in a more general history, 
and he decided to make Greek mathematics the subject 
of a.separate work. Such a book was very much 
wanted ; here, too, he was breaking new ground. 
There were three recent and important German works 
by Bretschneider, Hankel, and Moritz Cantor, but no 
book in English at all comprehensive. The under- 
NO. 2786, VOL. 111] 
NATURE 
calculation and Greek theory of numbers, with the- 
403 
but not by one of lower potential. Moreover, 
grains might clearly be of different degrees of 
sensitiveness—that is, they might require different 
amounts of energy to make them developable—and 
the whole idea of quantitative differences in sensitive- 
ness and exposure, which is so difficult if we imagine 
one quantum of energy per grain to be sufficient to 
produce a complete change in the grain which will 
make it developable, becomes perfectly intelligible. 
On the other hand, the division of the sensitive area 
into a number of small sensitive spots, which accords 
with the ideas both of Silberstein and those of other 
workers such as Svedberg who have located sensitive- 
ness in “centres,” would still enable us to retain the 
idea that a single quantum of energy is sufficient for 
exposure if it reaches one sensitive spot. 

Obituary. 
taking was the more arduous in that Gow had made 
no special study of mathematics since his school- 
days, and it is no small proficiency in mathematics that 
is required for the compilation of such a history. The 
work proved a little uneven owing to the fact that 
the arithmetical portion was written on a scale too 
large to allow of the history of geometry being treated 
with equal fulness if the whole work was to be in a 
reasonable compass; and Gow realised that with 
“a history like this... the utility will no doubt 
vary as the brevity ” (p. 145). 
The best possible test of a book is, perhaps, the 
impression that it makes upon a reader who takes it 
up thirty or forty years after its publication. This 
book stands the test well. It is true that the mass 
of the material that must be included appeared to 
Gow at times to be overwhelming ; for he speaks in 
his preface of the labour having often been dreary. 
But this certainly would not be gathered from the 
finished work, which is from first to last anything but 
dreary. Many things in it have necessarily been super- 
seded as the result of subsequent researches, but the 
book can still be read with the same pleasure as it 
aroused on its first appearance, 2 a a 
Rev. WILLIAM WILKS. 
HorticutturE is the poorer by the sudden death 
on March 2 of the Rev. William Wilks, vicar of Shirley, 
Croydon, 1879-1912. The son of Dr. G. F. Wilks, 
born at Ashford, Kent, on October 19, 1843, William 
Wilks was educated at Clapham and Pembroke College, 
Cambridge, where he took his degree in 1864. He was 
intended to follow his father’s profession, but forsaking 
that course, after studying at Wells, he took orders, 
and was appointed curate of Croydon in 1866. The 
rest of his life, except for his annual holiday on the 
Continent, or latterly in Scotland, was spent in that 
neighbourhood, and when in 1912 he resigned his 
vicarage he went to live and garden next door at the 
“ Wilderness ”’ which he had built, and where he died. 
There is no need to speak here of Mr. Wilks’s parish 
work—the concourse of local people at his funeral 
at Shirley showed how it was appreciated—but rather 
