92 



NATURE 



[A 



PRIL 3, I919 



develop a shaft horse-power of 10,500. Steam is 

 obtained from two boilers of the Yarrow tj'pe, working 

 at 235 lb. per sq. in. The turbine machinery is supple- 

 mented by an 8oo-brake-horse-power heavy oil engine 

 of the Vickers submarine type, which is coupled to a 

 dynamo of the open single-armature design. The tur- 

 bines are reserved for higher speeds only, whilst the 

 dynamo, in addition to charging batteries, supplies the 

 main motors with power for cruising at economical 

 speeds. For submerged work the motors develop a 

 total horse-power of 700 per shaft, and give a speed 

 of nine knots. The motors drive the shafts through 

 helical gearing. The storage battery for the use of 

 the motors is divided into three groups of 112 cells 

 per group. 



The following works are in the press for publica- 

 tion by the Carnegie Institution of Washington: — 

 " The Cactaceae : Descriptions and Illustrations of 

 Plants of the Cactus Family," N. L. Britton and 

 J. N. Rose, 4 vols., vols. i. and ii. ; "A Biochemic 

 Basis for the Study of Problems of Taxonomy, 

 Heredity, Evolution, etc., with Especial Reference to 

 the Starches and the Tissues of Parent and Hybrid 

 Stocks, and to the Starches and the Hemoglobins of 

 Varieties, Species, and Genera," E. T. Reichert ; "A 

 Biometric Study of Basal Metabolism in Man," J. A. 

 Harris and F. G. Benedict; "Distribution of Vegeta- 

 tion in the United States, as Related to Climatic 

 Conditions," B. E. Livingston and F. Shreve; "The 

 ■Ecological Relations of Roots," J. E. Weaver; and 

 "The Carbohydrate Economy of Cacti," H.A. Spoehr. 

 Mr. Edward Arnold's latest announcements include 

 the concluding volume of " Principles of Electrical 

 Engineering and their Application," Prof. G. Kapp ; 

 "Air Navigation: Notes and Examples," Capt. S. F. 

 Card; " Tacheometer Tables," Prof. H. Louis; and a 

 revised and enlarged edition of the translation, by Dr. 

 G. W. O. Howe, of Dr. A. Thomalen's "Text-book 

 of Electrical Engineering." Messrs. Hodder and 

 Stoughton are publishing "Automobile Repairing 

 made Easy," Capt. V. W. Pag^, and a new edition 

 of the same author's "The Modern Gasoline Auto- 

 mobile : Its Design, Construction, and Operation." 

 Messrs. Crosby Lockwood and Son promise "Aero- 

 plane Construction," S. Camm ; " Oils, Fats, and 

 Waxes," Dr. G. Martin; "Streamline Kite Balloons," 

 Capt. P. H. Sumner; "The Engineer's Year-Book 

 for 1919"; and a revision, by H. H. P. Powles. 

 of "Clark's Mechanical Engineer's Pocket-Book." 

 Messrs. Gauthieir-Villars et Cie (Paris) have in pre- 

 paration part iii. of Prof. E. Roth^'s " Cours de 

 Physique," dealing with " Aerodynamique " ; vol. iii. 

 of "CEuvres d'Halphen" is in the press for appear- 

 ance with the same publishers, and vol. iv. is in 

 preparation. 



OUR ASTRONOMICAL COLUMN. 



Comet 1914c (Neujmin). — A definitive orbit of this 

 comet is contained in Publication of the Stockholm 

 Observatory, vol. x., No. 6. The comet was dis- 

 covered on 1914 June 24 by M. Neujmin, of the 

 Simeis Observatory, Crimea, and fifty-one observa- 

 tions on thirty-six nights between that date and 

 December 22, the majority of which were made at 

 Mount Hamilton and Vienna, have been used to 

 determine its orbit. The points that specially call 

 for remark are that the orbit is hyperbolic, the eccen- 

 tricity being 100367 + 0-000296, and that the perihelion 

 distance is exceptionally large — 3-747. In spite of the 

 fact that the arc of the orbit comprehended in the 

 investigation is only 33"^ or 34°, the author, Mr. John 

 Svardson, is satisfied that the hyperbolic character 

 of the orbit is real. The large perihelion distance is 



NO. 2579, VOL. 1031 



equalled only by the comet of 1729, and there are 

 other resemblances between the orbits of the two 

 comets — a fact which had been previously noticed. 

 The elements found by Mr. Svardson are given below 

 with those of the comet of 1729 for comparison. 



ignc 1729 



T = 1914 July 30'I5» iJerlin M.T. 1729 June 13 2/ Paris M.T. 

 a. = 14" 2' i.i 5" 9" 53' 22" 



a =^70° 18' 267" 310° 36' o" 



i = 71" 2' 18-4' 77° 5' 18' 



'7=3747131 4-043496 



e = i 'OOjbja 1 '0050334 



Comet 1915a (Mellish). — Stockholm Publication 

 No. 5 (vdl. x.) contains a definitive orbit of this comet 

 by Mr. Rosenbaum. The orbit seems to be hyper- 

 bolic, eccentricity 1-000235, but the author is not 

 satisfied that this is real. It may be remembered that 

 in the middle of May the comet was observed to have 

 two nuclei visibly separated, and Mr. Rosenbaum 

 suggests that it is necessary to treat the observations 

 before and after the disruption as distinct orbits. 



The Cepheid Variables. — The characteristics of the 

 variable stars of which 8 Cephei is the type furnish 

 a problem which is occupying many minds : (i) Their 

 variation is regular and continuous, and the rise to 

 maximum is usually more rapid than the fall to 

 minimum ; (2) they sliow variation of radial velocity 

 with the period of the light changes; (3) their spec- 

 tral class varies with the period, advancing towards 

 M as the period is longer, and also with the light 

 variation, the stars being redder at minimum than 

 at maximuni; and (4) the period of light variation 

 has a marked correlation with the mean absolute 

 magnitude of any star. It is found difficult to pro- 

 pound a hypothesis that will account for these and 

 other characteristics. There is good reason for think- 

 ing that the Cepheids are not binary stars. It has 

 been suggested that they are rotating bodies hotter 

 and brighter on one side than on the other, but this 

 fails to fit the facts, and a third hypothesis, known 

 as the pulsation theory, which supposes that the 

 Cepheids are gaseous bodies alternately expanding 

 and contracting is now under discussion. The Monthly 

 Notices of the R.A.S. for November and January con- 

 tain a thermo-dynamical investigation of this theory b\ 

 Prof. Eddington, who discusses successfully the initial 

 difficulty that the dissipation of energy would not 

 permit the action to continue, and concludes that the 

 hypothesis leads to results in agreement with observa- 

 tion in respect of (i) the absolute value of the period, 

 which can be determined theoretically with small un- 

 certainty; (2) the correlation of spectral type with 

 absolute magnitude; and (3) the asymmetric form of 

 the velocltv curve. 



WAR WORK OF niUTLSH CHEMISTS. 



THE anniversary dinner of the Chemical Society, 

 was held at the Connaught Rooms on March 27,' 

 Sir William J. Pope presiding. In proposing the toast 

 of the Chemical Society, Lord Moulton stated that our 

 real enemy in the war was Germany — the nation that 

 had devoted itself par excellence to chemistry. Ger- 

 many did not declare war until her installations for 

 the production of ammonia and of nitrates in vast 

 quantities were complete. Emboldened by the enor- 

 mous preparation made for the supply of munitions, 

 by the advances made In artillery, and by the decision 

 to use poisonous gases, Germany thought she had but 

 to strike a heavy blow and world-supremacy was hers. 

 Lord Moulton then contrasted Germany's state of 

 preparedness in 1914 for .the production of munitions 

 with that of England. Chemists were justified In 

 claiming that it was they who had had to resist Ger- 



