28 



NATURE 



[September 5, igi: 



matters in Wales, and was widely known and 

 respected thruii,t;houl the country. 



We are i^dad to see thai progress is gradually beini;- 

 made with the synchronisation of clocks, thanks 

 largely to the enterprise of private companies. Last 

 rear a committee of the British Science Guild pre- 

 sented a valuable report upon the position of the sub- 

 ject and ihe svsleni em]>loyed bv the General Post 

 OlVice, and an instructive account of synchronisa- 

 tion and the im])orlance of correct time is given by 

 .Major O'Meara in an address printed in this year's 

 r.port of the Guild. The committee recommended 

 that, as a beginning, il would probably be well lo 

 have a few large public clocks in London synchronised, 

 and that these should be .set apart and considered as 

 "standard time clocks." An electric clock which may 

 be used for the purpose suggested by the cominittec 

 has just been built by the Silent Electric Clock Co., 

 192 Goswell Road, London, E.C., on the new mills of 

 the Hovis Bread Co., ^■au.\haIl Bridge Road. We 

 understand that this electric clock, with its four faces 

 each g ft. 6 in. diameter, is not only the largest elec- 

 tric clock in London, but is also to be controlled by a 

 master clock directly synchronised from Greenwich. 

 The clock thus reijnsints an up-to-date form of public 

 timekeeper which is likely to be extensively adopted 

 in the future. 



.A LOCAL society which possesses such a creditable 

 record of work as the Royal Cornwall Polytechnic 

 .Society does well to commemorate worthies who were 

 members of their body. In the first part of its Pro- 

 ceedings for 1912 it publishes portraits and lives of 

 three of its most eminent members. Sir C. Lemon, 

 F.R..S., first president (1S33-67), who did good ser- 

 vice to science by his attempt to found a school of 

 mines at Truro, a project which was in advance of 

 Ihe times when it was proposed, but has been since 

 realised; Lord de Dunstanville, first patron, scholar 

 and politician ; and last, but not least, Davies Gilbert, 

 who succeeded Sir Humphry Davy as president of the 

 Royal Society, an accomplished botanist and distin- 

 guished in other branches of science. In the annual 

 report the council takes occasion to congratulate the 

 Rev. Philip Carlyon, a former vice-president of the 

 society, on attaining the age of a hundred years in 

 December last. 



Volume xi. of the Zoological rublications of the 

 Field Museum is devoted to :ui account of the 

 mammals of Illinois ;md Wisconsin, comprising 

 502 pages of text and a large number of illustrations. 

 "Keys" to the various genera and their species are 

 given. 



In the report of the Field Museum of Natural His- 

 tory, Chicago, for 191 1, the director refers to the 

 .acquisition by the trustees of a site for a new building 

 in Jackson Park, immediately lo the north of the 

 |)resent structure. The plans for the new building have 

 been approved, and the specifications for the contracts 

 drawn up. The report is illustrated with photographs 

 of bird groups and other interesting exhibits recently 

 added to the museum. 



The Meteorological Service of Canada has issued 

 a very useful pamphlet on the comparison of the 

 NO. 2236, VOL. 90] 



.Vngstrom pyrheliometer and the Callendar sunshine 

 recorder, and the determination of the proportion of 

 heat received on a horizontal surface from the diffuse 

 radiation from the sky to that received from the 

 sun. The International Union for Cooperation in 

 Solar Research at its Oxford conference recommended 

 (i) the adoption of the former instrument, and (2) 

 comparisons between it and other standard instru- 

 ments, but except at laboratories and the larger 

 observatories little is yet generally known about its 

 working. The paper in question, prepared by Mr. 

 J. Patterson, under the direction of Mr. R. F. 

 Stupart, gives a very clear idea of the construcaon 

 and action of both the above instruments. The fol- 

 lowing are among the noteworthy features shown 

 by their comparison : (i) the maximum intensity of 

 radiation measured by the Angstrom instrument 

 occurred at apparent noon, and by the Cal- 

 lendar recorder about forty minutes later. (2) The 

 Angstrom instrument gave slightly higher values in 

 the afternoon than in the morning, and the Callendar 

 recorder much higher values. (3) In the early morn- 

 ing and late afternoon the Callendar instrument gave 

 higher readings than the Angstrom. (4) E.xcluding 

 the morning readings the greatest percentage differ- 

 ence occurred between gh. and loh. a.m. ; from about 

 ih. to 3h. p.m. the change in percentage was very 

 slight. 



Sir T. L. HE.vrn has now supplied an English 

 edition (Cambridge Press, 25. bi.) of the " Method " of 

 Archimedes, discovered by Heiberg in igoO. This 

 tract is of very great interest, because it gives 

 mechanical discussions of geometrical problems based 

 upon the principle of the lever. Thus we have the 

 rule for the quadrature of a parabolic segmen: which 

 Archimedes elsewhere proves by the method of ..-xhaus- 

 tion. .Archimedes expressly says that the " A'ethod " 

 does not supply demonstrations ; he does not give any 

 reasons, but no doubt he had in mind what we should 

 call the theory of infinitesimals of different orders. For 

 example, a triangular lamina may be roughly, but not 

 exactly, replaced by a set of parallel rectangular 

 strips ; to find the centroid of the triangle we must 

 find the limiting position of the centroid of the system 

 of strips. Among other noteworthy points it may 

 be observed that .\rchimedes arrived at the formula 

 for the volume of a sphere before he discovered that 

 for its area ; and that he attributes to Democritus the 

 discovery of the theorem that pyramids of equal bases 

 and altitudes are of equal \olume. The first proof, 

 allowed lo be rigorous, he assigns (as elsewhere) to 

 Eudoxus. .As usual, the editor's task is performed 

 with great learning and thoroughness ; his introduc- 

 tion in particular will be found extremely useful by 

 those who are not familiar with Greek mathematics 

 beyond the elementary stage. 



riic Central — the journal of Ihe City and Guilds 

 Engineering College — for August contains rui article 

 advocating the use of direct rather than alternating 

 currents in electric traction by Mr. L. Calisch, an 

 account of some recent improvements in vacuum 

 evaporation by Mr. W. .\. Davis, and a description 

 of the Boncourt svstem of gaseous combustion by one 



