3o6 



NATURE 



[May 6, 1920 



procurable. As might be expected, there is an un- 

 usually complete group of works on determinants and 

 allied topics. The gift is of special ihterest because it 

 is made to a public library. Several of our college 

 and university libraries have been enriched by similar 

 donations {e.g. there is the Graves collection at Uni- 

 versity College, London), The time has come when 

 we may hope that the reference departments of our 

 rate-supported town libraries will be strengthened in 

 a similar way. Of course, mathematics is not the 

 only subject deserving attention ; natural science, 

 history, archaeology, economics, etc., all have a claim 

 to be considered. Anyone who cares to examine the 

 present record of public research libraries will be con- 

 vinced that such gifts as that of Sir Thomas Muir are 

 not l ikely to be wasted. 



The meeting of the Physical Society of London on 

 March 26 took the form of a discussion on Einstein's 

 theory of relativity. Prof. A. S. Eddington opened 

 with an explanatory lecture. Prof. A. O. Rankine 

 described experiments undertaken in collaboration 

 with Dr. Silberstein on the influence of a gravita- 

 tional field on the velocity of light polarised in a 

 plane parallel to the field; the results of the experi- 

 ment were in accord with the theory. Sir Joseph 

 Larmor contributed a paper in the course of which 

 he remarked that "the unresolvable essence of rela- 

 tivity appears to be that we cannot get on without 

 some foundation to which phenomena are referred, 

 and with respect to which they are ordered to the 

 degree that is necessary for our reasonings." Refer- 

 ence was made also to the close relation between the 

 theory and the fundamental principle of least action. 

 That principle furnishes the most concise and elegant 

 means of comprehending Einstein's theory. Here 

 Helmholtz was a pioneer, not only in his grasp of 

 physical principles, but also in his appreciation of the 

 true nature of geometry. The searching question was 

 asked : " How is It that astronomers since Newton's 

 time have persisted in one special and very precise 

 illusion about the distribution of gravitation, whereas 

 really an unlimited choice is open? " Several 

 speakers raised questions about the interpretation of 

 the Michelson-Morley experiment, indicating that the 

 explanations offered both by Lorentz and by Einstein 

 still remain unconvincing to many physicists. 



There are many chemists, and doubtless other 

 scientific workers, who, busy with their everyday 

 duties, have not been able to follow closely the pro- 

 gress made during the last few years in the study 

 of atomic structure, and would welcome a con- 

 nected survey of recent experiments and present 

 views. Hence attention may be directed to an address 

 by Prof. A. Berthoud on "The Structure of Atoms," 

 a translation of which aopears in the Chemical News 

 of April 9 and 16. This gives, in simple language, 

 a very readable account of the matter. It shows the 

 connections which have been traced between the 

 phenomena of radio-activity, isotopy, atomic numbers, 

 Moseley's law, Bohr's theory, and the spectra of the 

 elements; and it indicates to what extent the funda- 

 mental characters of atomic structure may now be 

 NO. 2636, VOL. 105] 



regarded as known, however much of detail may still 

 be waiting for the sagacity of the investigator to 

 fill in. 



Messrs. Ilford, Ltd., in issuing a second edition 

 of their well-known booklet on " Panchromatism," 

 have taken the opportunity of revising it and making 

 some important additions. The largest of the new 

 sections explains the nature of three-colour photo- 

 graphy, in which is demonstrated the fact that in 

 three-colour half-tone prints, granting the use of satis- 

 factory inks, the result is the same whether the dots 

 are side by side or superposed. The variability of so- 

 called "white light", is treated of, the table of 

 the multiplying factors of colour-filters is greatly 

 extended, and a considerable number of new filters 

 are described. The most novel and interesting of 

 these last are the "photographic-vision" filters, 

 which have transmissions that correspond with the 

 sensitiveness of an orthochromatic or panchromatic 

 plate, and therefore, when looked through, give the 

 object or landscape the appearance that it will have 

 when photographed on the plate that it matches. 

 The effect of any colour-filter on the photograph is 

 seen at once by putting the filter together with the 

 "photographic-vision " filter in front of the eye. The 

 price of the booklet is 6d., or post free gd. 



Messrs. A. Gallenkamp and Co., Ltd., have for- 

 warded us a copy of their list (No. 72) of graduated 

 instruments for volumetric analysis. These include 

 burettes, pipettes, graduated cylinders, and various 

 kinds of measuring flasks for use in the chemical and 

 physical laboratory; we do not, however, notice 

 pyknometers in the list. The instruments are made 

 in three qualities, depending upon the degree of 

 accuracy required. Those intended for research and 

 special work (Grade A) are graduated according to 

 the regulations laid down by the International Con- 

 gress of 1909. Apparatus of the next quality 

 (Grade B) is intended for specially accurate com- 

 mercial analysis; and that in Grade C is suitable for 

 ordinary technical determinations and general school- 

 work. It is satisfactory to know that our makers 

 of scientific glassware are endeavouring to meet the 

 requirements of all users, including those of research 

 workers. Whilst writing on this subject we may 

 note that, from a report appearing in the Journal 

 of the Society of Glass Technologists (December, 

 19 19), there is a movement in Germany to restrict 

 and standardise the shapes and sizes of glass vessels 

 such as beakers, flasks, retorts, cylinders, and crystal- 

 lising dishes in order to eliminate unnecessary diver- 

 sity and facilitate replacement. The proposed 

 standard dimensions are quoted at length. 



Messrs. H. K. Lewis and Co., Ltd., 136 Gower 

 Street, W.C.i, have just issued a list (dated April) of 

 new books and new editions added to their medical 

 and scientific circulating library during January, 

 February, and March of the present year. Being very 

 comprehensive and carefully classified, it should be 

 useful to all who wish to keep abreast of current 

 scientific literature. Copies can be obtained free of 

 charge upon application to the publishers. 



