176 
NATURE 
[OcToBER 9, 1913 
of his special knowledge enables him to treat the sub- 
ject in a comprehensive and convincing manner. It is 
noteworthy to find that he considers it ‘‘ hopeless to try 
to explain the facts of mimicry in any other way than 
as the result of natural selection.”’ 
the field excursions and the discussions held at the 
meetings contain some valuable records, and the 
volume as a whole furnishes good evidence of the 
excellent work that may be done by local -societies, 
such as the present, in encouraging an intelligent 
interest in the objects of natural history. 
Petermann’s Mitteilungen for September contains 
a characteristic portrait of the late Prof. H. Credner, 
the well-known geologist of Leipzig. Dr. K. Andrée 
discusses the important question of the correlation 
of sedimentary rocks with conditions of deposition, 
as a guide in the formation of paleogeographic 
maps. 
Mr. C. A. Corron, of Wellington, N.Z., publishes 
a paper on the physiography of the Middle Clarence 
Valley, New Zealand (Geographical Journal, vol. 
xlii., p. 225), in which the influence of Prof. W. M. 
Davis is apparent in the lucid illustrations of local 
earth-structure and surface features. The author 
contests Park’s view that an ice-sheet passed across 
the district, which lies in the north-east of the 
south island. 
Messrs. W. Hanns, A. Ruhl, H. Spethmann, and 
H. Waldbaur, who accompanied Prof. W. M. Davis 
on a European tour in 1912, have published ‘“‘ Eine 
geographische Studienreise durch das _ westliche 
Europa’’ (Leipzig: Teubner, price 2.40 marks), a 
brochure which should well illustrate modern methods 
of investigation. The regions selected include Snow- 
donia, Cornwall, central France, and the famous 
Kirchet of Meiringen. 
Tue Journal of the Meteorological Society of Japan 
for May contains, inter alia, a useful article on the 
amount of evaporation of water, by Mr. Y. Horiguti, 
in which he gives some results of his investigation 
of the subject with a circular atmometer 8 in. in 
diameter, 4 in. in depth, and a small layer of water, 
the instrument being freely exposed to wind and sun- 
» shine. The determination of evaporation is a very 
uncertain operation, and in a recent essay (Strachan, 
“Basis of Evaporation’’) it is noted that the methods 
hitherto tried with tanks have been more or less 
failures, although, with the assistance of theory, 
better results ought eventually to be obtained. Many 
formulz by well known men of science already exist, 
and Mr. Horiguti has added another to the number. 
The result of his investigations shows that his for- 
mula, together with others referred to, will fairly 
well represent evaporation in the shade, but that in 
the open air this is not the case. He concludes that 
‘there remains an ample space for further studies.” 
In 1881 a MS. known as the Bakhshdali, from a 
village of that name in the Peshawar district, was 
discovered. If the view of Dr. Hoernle be accepted, 
that it belongs to the third or fourth century a.p., it 
would be of unique value as pushing back the mathe- 
matical knowledge of the Hindus to a date much 
earlier than has hitherto been admitted. The question 
NO. 2293, VOL. 92] 
The reports of | 
of date has been reopened by Mr. G. R. Kaye in © 
vol. viii., No. 9, of the Proceedings Asiatic Society — 
of Bengal for 1912. After 4 careful review of its 
contents he arrives at the conclusion that it is later ; 
than the time of Brahmagupta, or even later than 
Bhaskara. ‘‘The literary form and the mathematical 
form of the manuscript point to a comparatively late 
period; the script is not ancient; the notation used 
and the rules and examples have nothing ancient 
about them, and my general conclusion is that the 
manuscript was not written much before the twelfth 
century a.D. It may have been an adaptation of a 
more ancient work, but it is certainly not a faithful 
copy of any work composed much before the twelfth 
century.” It will be interesting to await Dr. 
Hoernle’s reply to this communication. 
In the Proceedings of the Tokyo Mathematico- 
Physical Society (2), vii., 5, Mr. S. Yokota gives an_ 
analytical solution of the stress distribution in a 
riveted plate due to a simple push applied to a rivet, 
the surfaces being smooth. The lines of principal 
stress are plotted. 
In addition to the usual lists of students and degree 
proceedings, the Johns Hopkins University Circular 
contains interesting mathematical notes edited by 
Prof. Frank Morley. Mr. J. E. Rowe, in a note on 
Fermat’s classical theorem, shows that the sum of 
two powers of integers cannot be the same power of 
another integer (excluding, of course, the case of 
second powers) unless the index is greater than 100 
and the largest integer greater than the twenty-ninth 
power of 10; and further, considering next the two 
types in which the greatest integer is odd or even 
respectively, the author says, ‘Also it is shown that 
one-half of all possible solutions of each of the two 
types just described are impossible” (!). In a note 
on self-dual rational quartics, Mr. L. E. Wear shows 
that the only quartic curves which reciprocate into 
themselves are the limacon and the obvious case of 
two conics. 
Pror. E. B. Witson, writing in the July Bulletin 
of the American Mathematical Society on the unifica- 
tion of vector notations, expresses a doubt whether 
the several steps which have been taken in this direc- 
tion recently have been steps ‘backward or forward, 
sideways or up in the air.” The committee appointed . 
at Rome in 1908 has not yet presented a report, so that 
not much of a step in any direction can be attributed to 
it. There has been great activity in the use of vector 
methods in Italy, which has served to stereotype the 
notations of Burali-Forti and Marcolongo, which 
differ from those in vogue in Germany and America. 
A valuable report by the late Dr. Macfarlane has 
been published in the Bulletin of the International 
Association for Promoting the Study of Quaternions 
and Allied Systems of Mathematics for June, 1912, 
and Prof. Wilson hopes ‘‘that the place of publication 
may not prove a burial ground for the essay.” Lastly, 
Langevin’s article in the French Mathematical 
Encyclopzedia proposes a systemof notations in which 
vectors are distinguished by interlineal superscripts, 
no special founts being used, and this seems likely 
to be widely adopted in France. 
