194 



NATURE 



[November 7, 1918 



pipes placed in the flue between the boilers and 

 the chimney. The f£ed-water passes through the pipes 

 its waj in the boilers, and takes up some oi the 

 deal from the waste furnace gases, which thus reach 

 the base of the chimney at a temperature lowei than 

 would otherwise 1"- the case, ["he exterior surfaces 

 oi the tubes are kept clean by scrapers, which travel 

 automatically up and down the tubes. In 155 plants 

 fitted with economisers the average efficiency of the 

 appliance was 114 per cent. The possible practical 

 efficiency is 17A per cent, to 20 pei cent. Only 17 per 

 cent, of the plants were saving 15 per cent, or mere of 

 the coal-hill, and more than 30 pei cent, of the plants 

 were saving less than to pei cent. The fault does 

 not lie with the economiser as an appliance, but is 

 due to the fact that the economical generation of 

 steam is not understood, and economisers are often 

 not installed on correct lines. 'The authors estimate 

 that a saving in this country of from 7,000,900 to 



[O, ,000 tons of coal per annum could lie obtained bv 



fhe use of economisers installed on correct scientific 

 lines. 



The Decimal Association, 212 and 213 Finsbury 

 Pavement House, Finsbury Pavement, London, E.C.2, 

 has published in pamphlet form the article on "The 

 [Metric System and Decimal Coinage" contributed by 

 Mr. Harry Allcock to the issue of Nature for June 6, 

 1918. It will be remembered that the article was 

 concerned with ihe attitude towards the metric system 

 of weights and measures and decimal coinage taken 

 by Lord Balfour of Burleigh's Committee on Com- 

 mercial and Industrial Policy after the War, and it 

 was shown that the decisions arrived at were open 

 to serious criticism. 



Dr. L. L. Fermor has pointed out to us, in con- 

 nection with our notice of his recent paper on hol- 

 landite (Nature, vol. ci., p. 392), that he used the 

 term " bipyramidal " as .1 synonym for the older 

 "pyramidal" in the paper itself. He also shows that 

 the' name " romanechite " is correctly accented, ac- 

 cording to French usage, although derived from the 

 place-name Romaneche, a good analogs being the 

 three words chcr, clicrc, and chiri. 



The Library Press, Ltd. (26 Portugal Street, 

 W.C.2), will publish shortly a translation, by B. Miall, 

 of Prof. J. Amar's "The Physiology of Industrial 

 Organisation and the Re-employment of the Disabled." 

 I In book is being edited by Prof. A. F. Stanley Kent, 

 who will supply to it an introduction and notes. 



I ASTRONOMICAL COLUMN. 



The Dark-line Spectrum of Nova Aquilje. — Dr. J. 

 sent to Nature some interesting details re- 

 lating to the transient dark-line spectrum of Nova 

 Aquilae, as photographed at the Cane Observatory with 

 an spectrograph on June 10, 11, and 12. 

 Apart from the bright and dark hydrogen spectrum 

 which was in process of development, the spectrum 

 was a continuous one crossed by a true absorption 

 spectrum consisting principally of the enhanced lines 

 of titanium, iron, chromium, strontium, calcium, 

 magnesium, and helium. As shown by iron com- 

 parison spectra, the entire series of lines was displaced 

 to the violet bv an amount representing a radiai velo- 

 city of 1500 km. per second (June 11 and 12). The 

 violet edges of broad absorption lines, lefl partially 

 uncovered by broad bright bands, do not appear to be 

 in question, and the displacement is regarded as a 

 true Doppler effect, due to the actual motion of a 

 stellar body possessing an intensely heated atmosphere 

 of metallic vapours. As in the case of other novae, 



NO. 2558, VOL. I02] 



the fine dark II and K lines appeared nearly in their 

 normal positions, but Dr. Lunt thinks it erroneous to 

 consider their small displacements as representing the 

 velocit} of the star; it serins to him more probable 

 that these lines do not originate in the nova itself, 

 but in a nebulous mass lying in the line of sight. 

 The residual incandescent and disturbed nebulous 

 matter left behind after the passage of a rapidl) 

 moving star into a nebula would seem to oiler a suffi- 

 cient explanation of the bright-line spectrum. To 

 account for the supposed enormous velocity of the 

 nova. Dr. Lunt suggests that our own system may 

 have .1 velocity comparable with those found for spiral 

 nebulae, and that the velocity may result, in part from 

 this motion, anil in part from the high velocity of a 

 wandering star which has come from outside our 

 system. 



As in Nova Geminorum, there were two sets of 

 dark hydrogen and helium lines during the earlier 

 Stages, the first of which showed the same displace- 

 ment as the enhanced metallic lines. On June 15 the 

 second set had become comparatively narrow and 

 sharp, and showed a displacement equivalent to 

 2286 km. per second; except for the K line, these 

 have no counterpart in the enhanced line spi 

 and their meaning remains obscure. 



Observations of Minor Planets. — Shortly before 

 the outbreak of war an important international scheme 

 of work on these bodies had been arranged, to secure 

 that all should be sufficienth observed without waste 

 of labour through overlapping. Though the organisa- 

 tion was shattered bv war, the' observations continue. 

 Marseilles Observatory undertook the circulation of 

 ephemerides and information generally; the recently 

 published Journal des Observateurs (vol. ii.. No. oi 

 contains observations of sixty-six planets made during 

 the pasl year by MM. Gonnessiat and Sy at Algiers 

 Observatory. They include some positions of Juno 

 and Vesta. It is a matter for regret that the Nautical 

 Almanac has discontinued its ephemerides of the four 

 principal asteroids. No predicted positions of them are 

 now available except the approximate ones in the list 

 published annually at Berlin. 



A Bright Meteor. — Astr. Nach. 1X0. 491 

 tains an account of a bright meteor which fell near 

 Treysa, in Hessen, o° 10' E. Gr., 50 55' N., on 

 loth April 3, 2h. 25m. O.M.T., the sun's altitude 

 bring 30 50'. It was" seen over a circle of 135 km. 

 radius, and heard, over a circle of 50 60 km. radius, 

 besides a fevt isolated points at [00 km. distance. Tb 

 earth-point was calculated, and a prolonged search at 

 length revealed the meteor in a wood. It had made 

 a hole i-6o metres drip, at an inclination of 6o° to 

 tin- horizpn, in a direction from N. 15° W. to S. 15 E., 

 well with the calculated values. It was 

 ! of iron, and weighed 63 kg. A. Wegener, 

 whose calculations led to its disci very, 1 stimated that 

 its final velocity was in the neighbourhood of 1 or 

 2 km. 'sec. The position of the radiant inferred (mm 

 the observations during flight is 357° + So°, and from 

 the direction of the hole in the ground 20°+78°. The 

 diffi n are is only 5 in great circle. 



THE HOT WORKING OF STEF.T.. 



IT is generally held that, in order to obtain the best 

 mechanical properties of which a steel is capable, 

 it is necessary, after having cast it in the form of an 

 ingot, to subject it to a large amount of deformation 

 either by forging or rolling or pressing at a high tem- 

 perature. Many official specifications, in fad, require 

 a given reduction of the original section of the ingot. 

 i h |uirements are expressed as "the coefficient 



