578 



NATURE 



[December 30, 1920 



speed after takinR- into account the power required 

 to drive the injection compressor. On an i.h.p. 

 basis the consumption is less with air injection, thus 

 indicating that the combustio-i is better with air 

 injection. Those interested in the dynamics of cam- 

 driven valves will find much of value in the paper. 



Mr. D. Brownlie has made a survey of a large 

 number of boiler plants, and in the Chemical Trade 

 Journal for August-September he published the 

 individual figures obtained relating to different indus- 

 tries. The details of the performance of sixty typical 

 steam-boiler plants used in chemical works are 

 tabulated, and he discusses their merits and demerits. 

 Since these tests were nof applied after careful pre- 

 paration of the plants, they may be regarded as repre- 

 sentative of normal working conditions. The true 

 average net working efficiency for the whole sixty 

 plants was found to be approximately 58 per cent., 

 but the author's experience leads him to the con- 

 clusion that a modern plant run on scientific lines will 

 give on the average 75 per c^t. net working efficiency 

 for continuous performance, a variation between 65 per 

 cent, with purely refuse coal and 825 per cent, with 

 the best quality coal being approximately the limits 



which should exist. If the average efficiency could be 

 raised from 58 per cent, to 75 per cent., obviously a 

 great saving would result, amounting to 285,000!. 

 per annum on the sixty plants tested. The reasons 

 given for the low results obtained are insufficiency of 

 grate length, economiser capacity, use of superheaters, 

 and insulating steam-pipe covering. Other causes 

 are that the feed-water is not properly treated to avoid 

 scale troubles, and that the combustion processes are 

 not chemically controlled by the use of recorders. 

 Brickwork and foundations, too, were found in a bad 

 state of repair, with a consequent leakage of cold 

 air. The author criticises the use of chimney 

 draught and steam jets when mechanical draught 

 would serve the same purpose more economically. 

 His great insistence, however, is on the necessity for 

 supervision of the plant according to modern scientific 

 methods, and he proceeds to summarise the rigid 

 system of record-taking, which he believes to be 

 essential if the best results are to be obtained. A 

 number of instruments useful for control purposes are 

 mentioned by name, but, of course, their relative 

 merits and demerits are not subjects which the author 

 can deal with in a single article. 



Our Astronomical Column. 



I920'0 



Skjellerup's Comet. — The following observation 

 was secured by Prof. Barnard at the Yerkes Observa- 

 tory : — G.M.T. December i8d. 2ih. 55-6m., R.A. 

 gh. 22m. 13s., S. decl. 1° 37' 49". The following pro- 

 visional orbit was deduced from the observations of 

 December 13, 17, and 18 : 



T = 1920 Dec. 13-1743 G.M.T. 



" =343° 47' 9" 

 !;^ = io7° 39' 23" 

 / = 23° 53' 10" 

 log f =0-06439 



Ephetneris for Greenwich Midnight. 



R.A. N. Decl. log r log i 



h. m. s. o , \ 



Dec. 31 101936 17 4 00776 9-4769 



Jan. 4 10 34 S3 22 25 00838 9-4972 



8 10 48 33 27 16 00909 9-5220 



12 10 59 58 31 29 00989 95503 



16 II 940 35x0 0107s 9-5799 



20 II 1742 3824 0-1167 9-6115 



The comet will not become conspicuous, but should 

 be readily visible until the moon interferes with ob- 

 servation towards the end of January. 



The January Meteors. — Mr. Denning writes : — 

 "The shower of Quadrantids (or Bootids, as they are 

 sometimes called) is due to recur on the nights of 

 January 2 and 3, and it is likely to be conspicuously 

 visible this year if the weather is clear, for there will 

 be no interference from moonlight. The most favour- 

 able time to observe the shower will be in the few- 

 hours preceding sunrise or in the early evening. 

 The strength of the shower apparently varies from 

 year to year, but its visible character is much affected 

 by moonlight and atmospheric conditions. The 

 nieteors are often brilliant and traverse long flights. 

 In iqi8 the radiant point seemed to be 7° or 8° north 

 of the usual position, and the display appeared to 

 be more abundant than usual." 



The Masses of the Stars. — The growth of our 

 knowledge of stellar masses has been slow ; it was 

 for a long trme limited to the very few cases of 



NO. 2670, VOL". 106] 



binaries the orbits and parallaxes of which were 

 known. The next extension came through the spectro- 

 scope, which demonstrated the binary character of 

 Algol variables and the existence of the class of 

 spectroscopic binaries. Although the individual masses 

 of the latter could not be found without a knowledge 

 of the inclination, the results could be used statis- 

 tically, assuming a mean inclination. One product 

 of this research was the fact that the B stars have 

 large masses. 



The idea occurred independently to Russell and 

 Hertzsprung that double stars showing curvature of 

 motion could be used statistically for mass-determina- 

 tion even when the arc described was so short that 

 the orbit could not be deduced. Russell concluded that 

 B stars and giant A stars had an average mass of 

 eight times the sun's, while the mass of the other 

 pairs was about double the sun's. 



.This latter result was provisionally adopted by 

 J. Jackson and H. H. Furner in a paper read to the 

 Roval Astronomical Society on December 10. They 

 utilised all available orbits of binaries, and also several 

 hundreds of other pairs the relative motion of which 

 showed curvature. The parallax of each pair was 

 deduced on the assumption that its mass was double 

 the sun's; its linear motion was then deduced from 

 its observed proper motion. 



The resulting aoex of the solar motion is R..^. 

 273-0°, decl. +33-8°, and speed 19-13 km. /sec. ; the 

 latter is so close to Campbell's spectroscopic value. 

 19-5 km. /sec, that it fulb- confirms the validity of 

 the assumption. 



H. v. Zeipel, in the course of an article on stellar 

 evolution in the December issue of Scientia, states 

 that an attempt is being made at Upsala Observatory 

 to obtain the relative masses of the giant stars of the 

 different spectral types bv a study of the grouping of 

 these types in the globular clusters. He says : "One 

 can demonstrate . . . that the massive stars congre- 

 gate in relativelv greater numbers than the light ones 

 towards the middle of the group. By careful study of 

 the distribution of the different types, one can deduce 

 the mass of each." The detailed results are not given. 



