'74 



NATURE 



[October 31, 1918 



- >[.i iin, humpback, and bottle-nosed whales taken 

 at these stations during this period. The numbers .m- 

 probably higher than most people would have sup- 

 posed. 



A new Journal <xj General Physiology is being 

 published under the auspices of the Rockefeller 

 Institute for Medical Research. The editors are 

 Profs. Jacques Loeb and YV. J. V. Osterhout. In 

 the first instalment, which has just reached us, there 

 are a number of interesting papers on photosynthesis, 

 colloids, internal secretions, and regeneration in 

 plants. Some doubt may be expressed, however, as 

 to the need for another addition to the large number 

 of journals devoted to experimental physiology and 

 biochemistry. 



Three important papers dealing with methods of 

 testing the hardness of materials were presented for 

 discussion at the Institution of Mechanical Engineers 

 on October 18. The first paper, by Prof. C. A. 

 Edwards and Mr. F. W. Willis, describes an impact 

 method. The instrument employed consisted of a 

 block of steel weighing 21 lb., which could be released 

 bv a mechanical device and allowed to drop 3 in. to 

 the surface of the specimen under test. The energy of 

 the blow was imparted to the surface of the specimen 

 through a hardened steel ball 10 mm. in diameter 

 firmly fixed to the weight. The impact energy was the 

 same in all cases, namely, 63 in. -lb. The specimen 

 was held very rigidly in a heavy steel base, and the 

 whole arrangement was carefully bedded on a massive 

 steel table. In another machine both weight and 

 height of fall could be varied, so as to give energies 

 of impact between 175 and 147 in. -lb. The results 

 obtained may be expressed by the equation d = CE "", 

 where d is the diameter of the indent made by a 

 10-mm. ball, C is a coefficient which varies with the 

 hardness of the metal, and E is the total energy of 

 impact. The second paper, by Mr. R. G. C. Batson, 

 of the National Physical Laboratory, dealt with both 

 static and impact methods. Within the limits of Mr. 

 Batson 's impact experiments it is shown that the 

 energy of the blow is proportional to the volume of 

 indentation for cone and ball indenting tools, and the 

 dynamic hardness number suggested is equal to energy 

 of blow in kg. /volume of indentation in cm. 3 

 Further, the energy of the blow is proportional to the 

 square of the spherical area of the indentation for ball 

 indenting tool only, and the volume of indentation (and 

 therefore the dynamic hardness number) is approxi- 

 mately independent of the form of the indenting tool 

 (cone, 10-mm. ball, and 476-mm. ball). The third 

 paper, by Prof. W. C. Unwin, deals with the Ludwik 

 hardness test, in which geometrically similar indenta- 

 tion- are made bv use of a right-angled cone. Prof. 

 Unwin suggests that a cone slightly truncated might 

 be employed with advantage ; such a cone is more 

 durable than one with a sharp point, and the results 

 differ slightly only. The discussion of these papers 

 brought out a great deal of valuable information, and 

 will be continued at the meeting on November 15. 



Among forthcoming books' of science we notice the 

 following: "Hot-bulb Oil Engines and Suitable 

 Vessels," W. Pollock, and 'The Production and 

 Treatment of Vegetal.!. Oils," T. W. Chalmers 

 (Constable and Co., Ltd.); '" Tri-lingual Artillen 

 Dictionary," E. S. Hodgson, ol. ii., Erench-Italian- 

 English, and vol. iii., Italian-French-English (Charles 

 Griffin and Co., Ltd.); and a new and revised edition 

 of the late D. K. Clark's 'Mecha cal Engineer's 

 Pocket-book," II. II. P. Powles (O. Fir Lock-wood 

 > Son 



NO. 2557, VOL. I02] 



OUR ASTRONOMICAL COLUMN. 

 Tin Pla'nei Jupiter.— This brilliant objei 



rise's at about 8 p.m., and is visible during the who), 

 of the nighl which follows. Its position is between 

 the Stars S and £ in Gemini, and, the north de- 

 clination being jj\ , the planet remains abov< the 

 horizon during [6| hours. During th. coming winter 

 it will be very favourably situated foi ti lescopic 

 observation. Mr. Denning states that tin- -1 . . . 

 spot continues faintly visible south of the hull, 

 bay in the south equatorial belt, and the former 

 objects have exhibited an increasing velocit) sinci 

 1900, whin the rotation period was 9I1. 55m. 41-55. In 

 the present yeat between Maj and August the period 

 had declined to oh. 35111. 31-45., as determined by Mr. 

 F. Sargent, of Bristol, from observations bj the Rev'. 

 T. E. R. Phillips and himself. On May 12 the 

 longitude of the red spot was 45 , and on Vugust g 25 . 



If the same rate of motion has been maintained 

 during the interval since August 9, then the present 

 place of the spot is in longitude 6°, and it follows 

 the zero meridian (system II.) given in the Nautical 

 Almanac (1918, p. 341) by about ten minutes. 



Early in December next the position of the red spol 

 may be expected to correspond nearh with th.- zero 

 meridian of system II., and will therefore transit at 

 the same time. It will be interesting to observe th( 

 times of mid-transit of the red spot, which maj bi 

 expected nearly as follows : — 



h. m. h. m. 



9 28 p.m. 



November 7 9 51 p.m. Decembei 



9. 11 28 „ 1 6 55 ,, 



14 to 33 „ 6 8 33 „ 



19 9 40 .. 

 -'4 s 45 •. 

 The hollow in the belt seems to havi been certainly 

 visible on Jupiter since Schwab, figured it on Sep- 

 tember 5, 183 1, while the red spot appears to have 

 been first seen and drawn by Dawes on November 27, 

 I357- 



The "great south tropical disturbance," which is 

 a very extensive dusky spot in the same latitude as 

 the red spot, has been visible since February, 1901. 

 It is now distended over about 185 degrees of longitude 

 from 265° to i)o°. Moving at a swifter rate than the 

 red spot, it has had the effect of considerably 

 accelerating the speed of the latter in late years. 



The Rate ok Stellar Evolution. — On the -lip- 

 position that Cepheid variation is due to some kind of 

 pulsation having the period of light variation, Prof. A. S. 

 Eddington has pointed out that the variations of period 

 indicated by theory may. provide a means of estimating 

 the rate of progress of stellar evolution (The Observa- 

 tory, vol. xli., p. 379). The periods of similar globi - 

 of fluid pulsating under their own gravitation would 

 be inversely proportional to the square roots of the 

 densities, and the changes of density in a particular 

 star might therefore be deduced from the change of 

 period. Adopting Chandler's estimate that the period 

 of SCephei (5-366 days) is decreasing 0-05 sec. an- 

 nually, the star would double it- density in rather 

 more than three million years, and would take about 

 ten million years to pass from type l. to type E. 

 This rate of change is much slower than that derived 

 from the assumption that contraction is the source 

 of the star's heat. The time-scale would, in fact, be 

 enlarged a thousandfold, and would become more con- 

 sistent with present views as to th< age of terrestrial 

 rocks, the development of the earth-moon system, and 

 geological .ban".-. Observations of the change of 

 period in Cepheid variables would therefore seem to be 



of possil.K great importance-, and it is fortunate that 



th. \ .an usually be determined with great accuracv. 



