400 



NATURE 



[December i8, 1919 



greatest yield being attained when the proportion of 

 fat to mannitol corresponds with two molecules of the 

 former to three of ihe latter. The other products of 

 the reaction are chiefly water, a little alcohol, and a 

 substance many properties of which are similar to 

 those of the original fat. The composition of this 

 latter substance corresponds with that of a mixture of 

 the di-oleates (or distearates) of mannitan and iso- 

 mannide. 



The first numbor of the N.P.L. Revieiv, edited by 

 members of the staff of the National Physical Labora- 

 tory, Teddington, appeared in November. Its thirty- 

 six pages contain a large amount of information on 

 the scientific and other activities of the staff, much 

 of which will prove of interest to the general public 

 as well as to those for whom it is primarily intended. 

 Now that the laboratory is a Government institution, 

 it seems reasonable that its work should be more 

 widely known than it has been in the past, and readers 

 of the review will find in it a clear statement of the 

 way in which the laboratory has been fitted into the 

 organisation of the Scientific and Industrial Research 

 Department. From the articles on the old and new 

 directors it appears that the process of fitting has 

 necessitated a decrease in the responsibility of the 

 office, and under Treasury regulations there seem now 

 to be difficulties in the 'way of rewarding merit by 

 increase of salary. Seven or eight pages are devoted 

 to notes on the most important work passing through 

 the various departments. All are interesting, and 

 show clearlv how the scientific problems of the indus- 

 tries are being solved. The staff of the laboratory is 

 to be congratulated on its new publication. 



The power required for actuating the plant and 

 machinery of the Panama Canal is obtained by utilis- 

 ing the flow of surplus water over the Gatun Dam, 

 the height of which above sea-level enables an average 

 effective head of 75 ft. to be realised throughout the 

 year. The power plant at first installed comprised 

 three turbines, each of a rated capacity of 2250 kilo- 

 watts when running at 250 revs, per minute and 

 supplied with 500 cu. ft. of water per second. A 

 flow of 500 cusecs, with a fall of 75 ft., produces 

 nominallv 3160 kilowatts, so that there is an efficiency 

 margin of 37 per cent. The demand has been found 

 to be much under-estimated, and it has become neces- 

 sary not only to provide three additional machines of 

 greater capacity, but also to increase the output of 

 the existing- generators. Of the three additional 

 machines onlv one is yet in position, but when the 

 installation is complete there will be three units of 

 2880 kw. each and three units of 4500 kw. each, 

 totalling 22,140 kw., and requiring a supply of just 

 over 4000 cu. ft. of water per second. The electric 

 energy is emploved to drive the machinery of the locks 

 at Gatun, Miraflores, and Pedro Miguel, of the 

 haulage locomotives, of the permanent machine-shops, 

 of the drv dock, and of the coal-handling plant, 

 besides lighting the locks and manv towns comprised 

 within the canal zone — a stretch of country ten miles 

 in width across the isthmus. We are indebted for the 

 foregoing particulars to an article in the Engineer of 

 December S- 



Mr. E. a. Martin, the author of " Dew-Ponds," 

 is bringing out through Messrs. Allen and Donaldson, 

 Ltd.. 57 Marsham Street, S.W.i, a book entitled 

 " Life in a Sussex Windmill," recounting his experi- 

 ences of three years in a somewhat unusual dwelling, 

 and giving particulars of his observations of Nature 

 on the Sussex Downs. The portions ot the book 

 which will be of special interest to readers of Nature 

 are the chapters devoted to the geology of the Downs, 

 NO. 2616, VOL. 104] 



the problem of the dry combes, prehistoric man and 

 marling, water-supply, fossil oysters, Sussex iron and 

 wood, and the possible discovery of coal in the 

 county. 



The Cambridge University Press has in preparation 

 "The Cambridge Ancient History," the general plan 

 of which will be similar to that of the Cambridge 

 .Modern and Medieval Histories. It will be in eight 

 volumes, and, beginning with an account of archaeo- 

 logical discovery, will trace the history of Egypt and 

 Babylonia, Assyria and Persia, Greece and Rome, to 

 324 A.D. The work will be edited by Prof. J. B. Bury 

 and Messrs. S. .A. Cook and F. E Adcock. 



OUR ASTRONOMICAL COLUMN. 



The December .Meteoric Shower. — -Mr. Denning 

 writes that this display was well observed at Bristol 

 on the night following December 13. The early 

 evening was overcast, but after a storm of rain at 

 10 p.m. the sky cleared, and between loh. 30m. and 

 midnight meteors were observed to be falling at the 

 rate of thirty-five per hour. The moon rose just- 

 before I2h., and during the next hour, when her light 

 and films of thin cloud obscured some of the smaller 

 meteors, the horary rate decreased to seventeen. 

 There were two radiants, viz. at 114° -4- 335° (eighteen 

 meteors) and at 107° + 24° (twelve meteors), but the 

 marked differences in aspect of the members of the 

 two streams were very pronounced. The first-named 

 radiant represented the true Geminids, and they are 

 of moderate speed, with short paths sometimes stellar 

 in aspect, and of a sparkling silvery-white colour. 



.A brilliant Geminid was seen at iih. 40m. falling 

 from 131°+ 10° to i38° + o°, and giving a succession of 

 flashes. It lit up the foggy, humid atmosphere, and 

 was much brighter than Jupiter, slightly to the east 

 of it. This meteor must have been a splendid object 

 as seen from the Eastern Counties of England, and 

 it is hoped that further observations will com_e_ to 

 hand. A verv conspicuous lunar halo was visible 

 during the early morning hours of December 14. 



Discussion on Relativity. — The meeting of the 

 Royal Astronomical Society on December 12 was 

 entirely devoted to the consideration of the theory of 

 relativity. The discussion was opened by Prof. 

 Eddington, who said that while on the first relativity 

 theory tirne was adopted as the fourth co-ordinate 

 merely as a convenient .system, in Einstein's theory 

 the time-space continuum was inextricably blended, 

 so that what was pure time to one observer was 

 resolved into partlv "time, partly space for another, 

 differentlv circumstanced. The distinction between 

 past and future was, however, for sentient beings 

 somewhat greater than that between right and left. 

 If space were re-entrant and finite, the section of the 

 continuum in the time direction would be hyperbolic, 

 so that time would not repeat itself after an enormous 

 interval. 



Dr. leans said that phxsicists had other than astro- 

 nomical grounds for asserting that the foundation- 

 stone of the new svstem was "well and trulv laid." 

 It was originallv built on experiments, and since its 

 enunciation further experiments had confirmed its 

 truth. He gave the expressions for a wave-front of 

 light, stating that an observer initially at its source 

 remained central in soite of his own movement. 



Sir Oliver Lodge referred to some of the apoarent 

 paradoxes that had been uttered, and said he preferred 

 to take the aether, not the observer, as his b-nse of 

 reference, instancing the confused idea of theland- 

 scane that one obtained when travelling bv train. 



Dr. Silberstein pointed out that the star displace- 



