December 5, 1918] 



NATURE 



271 



supplied the Royal Mint, fur Imperial coinage, with 

 silver and bronze blanks. The general account of 



- and receipts show- a profit of 4-5!. millions, 

 as against 47!. millions in the previous year. Tin- 

 principal item included is the profit on the silver 

 coinage, but although the issue of silver coins in [916 



iter than in 1915, the higher cost of the bullion 

 resulted in a reduction in the net profit under this 

 head. Receipts of work done for the War Office show 

 a considerable increase in value, but the suspension 

 of ColoniM coinages has resulted in the disappear- 

 ance of any item on this account. As was to be 

 expected, general expenses were decidedly higher than 

 in previous Mars. 



The important bearing on the food supply of arti- 

 ficial manures containing phosphorus lends particular 

 a communication by Dr. C. Doelter in the 

 hische Chetmker- und Techniker-Zeitung for 

 September 15 and October 1 regarding the mineral 

 t the Ukraine. Phosphorite is found there in 

 nianv districts, in some parts in great abundance. 

 Large quantities are said to be obtainable from open- 

 cast workings at low cost, ('.round phosphorite was 

 exported to Austria in considerable quantities before 

 the war. It generally contains a high percentage of 

 calcium phosphate, while analysis shows 27-5 per cent, 

 of phosphoric acid. To derive the full value from the 

 deposits thev should be worked systematically, and not 

 by the primitive methods employed formerly. 



Dr. Beckmann recently gave an account before the 

 German Institution of Electrical Engineers of the pro- 

 gress that has been made in training disabled soldiers 

 to enable them to carry out work in engineering fac- 

 \ number of photographs are reproduced in 

 FJektrotechnische Zeitschrift for September 19 and 26 

 (in which the account is published) showing the 

 adopted to enable such men to operate 

 machine-tools; Particular stress is placed on the suc- 

 cess of a method, devised by Dr. Krukenberg, to 

 enable soldiers who have suffered amputation of the 

 forearm to work machines. A further communication 

 bv P. Perls refers to the employment of the blind in 

 factories. The photographs show men at work on a 

 variety of machining operations and the means of 

 protecting them from accidents. It is stated that 

 blinded soldiers have been employed with success in 

 twenty-six occupations. 



The law of decav of phosphorescent light emitted 

 bv a bodv after stimulation has hitherto been taken 

 to be of simple form. If I is the intensity and t the 

 time since stimulation, I was taken inversely propor- 

 tional to (a + bt) 2 . According to a communication to 

 the National Academy of Sciences of America by Prof. 



E. L. Nichols and Mr. II. L. Howes, which appears 

 in the October issue of the Proceedings of the 

 Academy, the law of decay is not so simple. They 

 find that there are two types of decay for the phos- 

 phorescence of short duration. If the inverse square 

 root of the intensity as ordinate is plotted against the 

 time as abscissa, in the first type the curve rises as 

 the time increases, but the rate of rise decreases as 

 time goes on; and in the second the curve rises, and 

 the rate of rise increases with the time. The first type 

 of phosphorescence the authors propose to call the 

 "persistent," and the second the "vanishing," type. 

 The two types may be exhibited by the same material, 

 e.g. calcite, stimulated bv ultra-violet light, gives phos- 



nce of the vanishing, and, when stimulated 

 Ithode rays, of the persistent, type. 



Among forthcoming books we notice "Technical 

 Handbook of Oils, Fats, and Waxes," P. J. Fryer and 



F. E. Weston, vol. ii. (Cambridge University Press); 



NO. 2562, VOL. I02] 



" Lice and their Menace to Man," Lieut. LI. Llovd, 

 with a chapter on "Trench Fever," by Major W. 

 Byam, K.A.M.C, illustrated (Henry Frowdc and 

 H odder and Stoughton) ; "The Iron Circle: The 

 Future of German Industrial Exports," Prof. S. 

 Herzog, translated (Hodder and Stoughton); "Text- 

 book of Military Aeronautics," II. Woodhouse (T. 

 Werner Laurie, Ltd.); "Boiler Chemistry," J. H. 

 Paul, a new edition of Bale's " Handbook for Steam 

 1 sers" (Longmans and Co.); and "The Mechanics' 

 and Draughtsmen's Pocket-book," W. E. Dommett, 

 and a new edition of Poole's "Telephone Handbook" 

 [Sit Isaac Pitman and Sons. Ltd.). 



OUR ASTRONOMICAL COLUMN. 



Distribution of Globular Clusters. — In continua- 

 tion of his previous investigations of the distances of 

 globular clusters, based upon the interdependence of 

 absolute luminosity and period in the case of Cepheid 

 variables, Dr. Harlow Shapley has reached impotU-.nt 

 conclusions regarding the extent and arrangement of 

 the sidereal system (Proc. Nat. Acad. Sci., vol. iv., 

 p. 224). The clusters appear to form a large flattened 

 system, the centre of which is in the galactic plane, 

 at a distance of between sixty and seventy thousand 

 light-years, in the general direction of the star-clouds 

 of Sagittarius and Scorpio. The arrangement of the 

 clusters and the relative densities of various parts of 

 the Milky Way clouds strongly suggest that the whole 

 sidereal system is roughly outlined by the globular 

 clusters, and that stars, nebulae, and clusters ;.re all 

 members of a single unit. The mean diameter of the 

 proposed system appears to be at least 300,000 light- 

 years. A further investigation has verified the exist- 

 ence of a local cluster of stars having a diameter of 

 about 2500 light-years, and containing most of the 

 brighter B stars, a majority of the A stars, and many- 

 stars of redder spectral types. The motion of the 

 cluster as a whole is in the galactic plane, and nearly 

 radial from the galactic centre. The observed sys- 

 tematic motions of the stars may be 1. xplained by the 

 movement of the cluster through the general field of 

 stars. 



A New Type of Nebular Spec trim. — Dr. V. M. 

 Slipher has made the interesting discovery that two 

 of the variable nebulae give an emission spectrum 

 which is quite unlike that of the ordinary gaseous 

 nebula? (Lowell Obs. Bull. No. 81). The spectrum of 

 Hubble's variable nebula, N.G.C. 2261, was photo- 

 graphed in December, 1917, with a total exposure of 

 nearly thirty-seven hours, the slit being placed north 

 and south over the nebulosity and nucleus. In most 

 essentials the spectrum of the nebula is identical with 

 that of a new star in the early bright-line stage, 

 when the majority of the lines, other than those of 

 hydrogen, are identical with enhanced lines. The 

 resemblance to the typical nova spectrum is further 

 emphasised bv the presence of absorption bands on the 

 more refrangible sides of the bright lines of hydrogen. 

 The variable nebula N.G.C. 6729 reaches only a low 

 altitude at Flagstaff, but, so far as can be judged from 

 the photograph obtained, its spectrum is a duplicate 

 of that of Hubble's nebula. The latter is of 

 "cometic" form, and the nucleus is the variable star 

 R Monocerotis, which was of the 12th magnitude 

 when the spectrum photograph was obtained. The 

 light of the nucleus is identical with that of the 

 nebula, and it is therefore probable that the nebulosity 

 derives its light from the star. The further study o'f 

 these objects may well be expected to throw consider- 

 able light on the nature of temporary stars. 



