March 13, 1919] 



NATURE 



•with two of these names, leaving the first word for 

 the definition of persons enj^aged more obviously in 

 the extension of chemical knowledge or the aj^lica- 

 tion of chemical principles. 



Pharmacy is an honourable occupation, and I can- 

 "•)t believe that the pharmacist would lose dignity or 

 aus by the change. Comparatively few pharmacists 

 i chemists in the modern sense, and it is well 

 Known that in other great countries this confusion of 

 \itles does not prevail; in fact, this is one of the few 

 points on which we are at variance with our Allies, 

 whilst they are in complete harmony with the Hun. 



M. O. FORSTER. 



Iavage Club, W.C.2, March 4. 

 Graphic Methods in Nautical Astronomy. 

 H the issue of Nature published on October 24 

 (vol. cii., p. 155) there appeared an account of 

 ingenious chart devised by Mr. G. W. Littlehales, 

 of the United States Hydrographic Department, for 

 dealing rapidly with certain problems in nautical 

 astronomy which involve the solution of a spherical 

 triangle when the three sides, or the two sides and 

 h(> included angle, are known. The article is entitled 

 V New Graphic Method in Nautical Astronomy," 

 !t it would appear that the idea has been familiar in 

 i- ranee for more than five-and-twenty years. The 

 possibility of constructing a chart like that made by 

 Mr. G. W. Littlehales was demonstrated by Maurice 

 d'Ocagne so long ago as 1891 in his work " Nomo- 

 graphie : les calculs usuels effectues au moyen des 

 abaques," p. 84, and an abacus devised bv him on 

 iliese lines was described in W. Dyck's " Katalog 

 mathematischer und mathematisch-physikalischer 

 Modelle, Apparate und Instrumente," published in 

 1.S92, p. 163. A figure of the chart can be found in 

 1 paper by d'Ocagne which appeared in the Journal 

 I'Ecole Poly technique (second series, 4th cahier, 

 )8, p. 224), and also in his "Traits de Nomo- 

 . graphic," 1899, p. 328. In a modified form the 

 chart was employed by E. Collignon in 1898 (see his 

 \ote sur la determination de I'heure du passage du 

 Ifil dans un plan vertical," Journal de I'Ecole Poly- 

 linique, loc. cit., pp. 123-35). 



As drawn by Mr. Littlehales the chart occupies a 

 uare of 15-in. side. From 5° to 175° it is graduated 

 single degrees, and over a large part of the scale 

 !i be read by estimation to 6'. AltTiough the 

 iiting of two copies obtained from Mr. Potter, 

 ^ent for .Admiralty charts, Minories, London (price 

 6d. each), is roughly executed, the chart is capable 

 doing good service in providing a rapid means of 

 "hocking the results of calculation. The particular 

 -IS in the solution of spherical triangles it is de- 

 nned to deal with, frequently occur in the reduction 

 crystal measurements, and the use of the chart 

 1 be confidently recommended to crvstallographers. 

 A. Hutchinson. 

 Ill ^^^ Mineralogical Laboratory, Cambridge, 

 IL? February 26. 



^^K- Curious Markings on Chalk. 



^^Hh 'Nature of March 6 there appeared a short 

 ^H^ce of a piece of chalk said to be carved to repre- 

 ^Hhit a mammoth. This specimen was described and 

 ■^j^ired by Mr. R-eid Moir in the February issue of 

 }[an. p. 17, pi. B. Examination of the figures there 

 Liven shows that the object is nothing more than 

 somewhat imperfect natural cast of a chamber 

 the shell of an Ammonite. It is significant that 

 . some parts of the country where such casts are 

 not uncommon the quarrymen call them "pigs." 

 Chas. W. -Andrews. 

 British Museum (Natural History), March 8. 

 NO. 2^76. VOL. 10^1 



Globular Clusters, Cepheid Variables, and Radiation. 



(i) The determination of the past duration of solar 

 radiation, and, consequently, the problem of the age 

 of the inhabitable earth, imposes upon theories of 

 radiation a difficulty the magnitude and fundamental 

 importance of which appear to be too infrequently 

 considered. The difference in the time-scales derived 

 from the gravitational theory of solar energy and 

 from geological and astronomical observation is jiot 

 one of a few per cent, (or less) of the basic quantities 

 involved, as is generally the case with the discrepancies 

 that have led to conspicuous modifications of radiation 

 theories; the discrepancy is rather a matter of a 

 hundred to one, or even of a thousand or more to one. 

 .V more glaring disagreement could scarcely be 

 imagined between a generally accepted and thoroughly 

 workable theory on one hand, and, on the other, a 

 mass of observation now too extensive and varied to 

 be denied and some equally formidable physical laws. 



Until recently the arguments for a long time-scale 

 have been mostly geological and biological, and they 

 have not been strongly insisted upon ; imperfections 

 in the geological records have been held to minimise 

 the disagreement with the Helmholtz-Kelvin contrac- 

 tion theory of the sun. Similarly, the arguments for 

 the short time-scale have not been too convincing, to 

 some geologists at least, because of the promising 

 possibility of finding new sources of energy or other 

 escape from the physical theory. Hence on both 

 sides of the question there has been a feeling of un- 

 certainty relative to the validity and finality of oppos- 

 ing arguments, and on neither side has the dis- 

 crepancy been strongly emphasised as a critical point 

 for theories of radiation and the structure of matter. 



(2) In recent volumes of Nature the limited possi- 

 bilities of the gravitational contraction of the sun 

 in the problem of the age of the earth have been 

 argued anew by Lindemann,^ Jeans, ^ and Eddington.* 

 The energy of contraction, as is well known, is essen- 

 tially self-regulating for gaseous stars, and its evalua- 

 tion is a clear and straightforward process. The 

 available supplementary sources of energy seem in- 

 competent ; the heat of chemical combinations, an 

 assumed increase in the specific heat, any definitely 

 recognised atomic supply — all such as these appear 

 quite insufficient to affect the problem. In fact, Jeans 

 has shown by a calculation, remarkable both for its 

 brevity and directness, that the total capacity of all 

 electrical sources of energy (including the chemical 

 and radio-active) must be comparatively small. He 

 concludes : " It accordingly looks as though the Helm- 

 holtz contraction will provide much more energy than 

 any other source, and we must apparently adjust our 

 vie'ws to the time-scale set by the contraction theory." 



Eddington * has pointed out irnportant objections to 

 the rather bizarre conception of obtaining great stores 

 of energy through the gradual annihilation of matter, 

 positive and negative electrons occasionally annulling 

 each other. 



Hence, unless we question, in some manner wholly 

 new, the strict application of the gravitational theory, 

 we may feel now more certain than over that the 

 sun could have radiated at the present rate for only 

 a few million years. 



(3) The main purpose of this note is to remark that 

 recent developments in stellar astronomy make it 

 unnecessary to relv on geological evidence alone for 

 the proof of a vastly longer duration of solar radiation 

 than the gravitational hypothesis admits. Thus the 

 argument need no longer involve only the indefinite 

 opposing of the tenets and conclusions of one science 



1 Vol. xcv., pp. ao3, 372 (1915). - Vol. xcix., p. 444 (i9»7)- 



" Vol. xcix., p. -»<5 ('017). 



* Loc. cit. and Monthly Notices, vo'. Kxvii., p. fiit (1017I. 



