April 12, 19 17] 



NATURE 



13: 



OUR ASTRONOMICAL COLUMN. 



Comet 1917a (Mellish). — Prof. Stromgren an- 

 nounces that from observations made on March 22, 

 2;^, and 24 (Copenhagen) Mrs. J. Braae and J. Fischer- 

 Petersen have calculated the following orbit and 

 ephemeris : — 



T= 1917 April 9-4463 G.M.T. 

 (u= 106' 51' 66^ 

 Q= 92° 47' 32 -1917 



/= 22"^ 48''92j 



log i^ = 94 1 464 

 Ephemeris : Greenwich Midnight. 



1917 R.A. Decl. Log r Log a Mag. 



h. m. s. . , 



April II 04349 +1130-3 9-4295 98894 4-6 



15 o 25 7 5 48-7 9-5156 9-9206 5-2 



17 o 20 53 3 32-6 9-5672 9-9407 5-6 



19 018 45 +1 39-0 9-6172 9-9608 5-9 



The April Lyrids. — This shower of meteors, 

 though occasionally offering a brilliant display, is, in 

 the majority of years, very slightly visible. It is 

 unfortunate that the f>eriod is not definitely known, 

 though there are indications that its best returns 

 occur at intervals of a little more than sixteen years. 

 This feature is by no means supported on conclusive 

 evidence, but it is a point worthy of further investiga- 

 tion. 



Abundant showers of Lyrids were observed in 1803, 

 1851, 1884, and 1901, and it w^ill be interesting to 

 determine whether or not an unusual exhibition of 

 these meteors is presented this year or in 1918. The 

 time of maximum will possibly be at about midnight 

 on April 21, and as there will be no moonlight to 

 interfere, it will be easy to ascertain the character 

 of the display should the weather prove suitable. If 

 the meteors reappear at the time mentioned it will 

 be important to observe the time of maximum and 

 the horary number visible. The position of the 

 radiant is already well known, and it moves east- 

 wards, like that of the August Perseids. Though 

 the chief activitv of the Lyrids seems confined to a 

 few hours, yet there are occasional specimens cer- 

 tainly seen between April 16 and 26, and possibly on 

 dates still further removed from the night of 

 maximum. 



V.ARiABiLiTY OF Uranus. — Prof. E. C. Pickering has 

 announced an interesting discovery which has followed 

 from a series of photometric observations of the light 

 of Uranus, made by Mr. Leon Campbell with the 

 primary object of investigating possible changes in the 

 light-emission of the sun (Harvard Circular, No. 200). 

 The observations revealed a variation in the light of 

 the planet amounting to about 01.^ magnitude in a 

 period of 0-451 day, these figures being based upon 

 2q6o settings. The period of variation agrees very 

 closely with that of the rotation of the planet derived 

 from spectroscopic observations by Lowell and Slipher, 

 and Prof. Pickering concludes that the variation in 

 light is due to unequal brightness of different portions 

 of the planet. If the variations in brightness prove to 

 be permanent, photometric observations will give the 

 rotation period of the planet with a high degree of 

 accuracy. 



The "Annuaire Astronomique " for 1917. — The 

 issue of this well-known publication for the current 

 year contains the usual astronomical information in a 

 convenient and interesting form, together with a review 

 of the progress of astronomy. It forms a valuable 

 work of reference for ..stronomical data of all kinds, 

 including a catalogue of minor planets arranged in the 

 order of their dfstances from the sun, a list of tem- 

 porary stars which have been visible to the naked eye, 



NO. 2476, VOL. 99] 



a list of stars with large fwoper motions, and so on. 

 Among the 140 illustrations we note a useful set of 

 diagrams from which one can readily ascertain the 

 visibility of each of the principal planets on any night 

 of the year. M. Camille Flammarion is to be con- 

 gratulated on having so successfully conducted this 

 publication for more than half a century. 



HEAT ECONOMY IN METAL MELTING. 



npHE outstanding feature of the proceedings at the 

 ^ annual meeting of the Institute of Metals, held 

 at Burlington House on March 21 and 22, was a 

 general discussion on metal melting, organised by the 

 council. Whether it was chiefly due to the fact that 

 this subject aroused an unusual amount of interest 

 among the members, or that war problems in metal- 

 lurgy have created a desire to discuss those problems 

 more freely than hitherto, the fact remains that in 

 the last three months the institute has added more 

 new members than it did in the previous two years; 

 that the attendance was ver)- much larger than it 

 has ever been at any other meeting in the course of 

 its history ; and that the discussions on the various 

 papers contributed were of unusual fullness and 

 value. 



S{>ecial appropriateness attached to the fact that Sir 

 George Beilby, the president of the institute, in enter- 

 ing on his second year of office, presided over a dis- 

 cussion which must have been of considerable interest 

 to him in his capacity of Director of the Fuel Research 

 Board set up by the Committee of the Priw Council 

 for Scientific and Industrial Research. Although coke 

 constitutes the fuel most generally used in metal and 

 alloy melting, only one paper was contributed dealing 

 with its use. On the other hand, four papers were 

 concerned with coal-gas, and these included one on the 

 practice of the Royal Mint, and another on the applica- 

 tion of the high-pressure gas system installed by the 

 City of Birmingham Gas Committee. Of the remainder 

 one paper dealt with producer gas, another with oil 

 fuel, and a third with an electric resistance furnace. 

 All these papers dealt with the melting of metals and 

 alloys in crucibles, i.e. in quantities which seldom 

 exceed 200 lb. in weight. The one paper on the subject 

 dealing with principles rather than practice was by Dr. 

 Carl Hering, an expert on furnace construction, and 

 was entitled " Ideals and Limitations in the Melting of 

 Non-Ferrous Metals." This, in many respects the 

 most suitable for discussion, was not discussed bv anv 

 of the speakers, and '.ill be briefly commented on in 

 this article. 



Dr. Hering enumerates the directions to which per- 

 fection points as follows : — A reduction in (i) the loss 

 of heat, (ii) the loss of metal, (iii) the number of bad 

 castings, (iv) the consumption of equipment, and (v) the 

 cost of labour and plant per lb. of good castings. As 

 these are not all independent factors, economv mav 

 sometimes result from increasing some if others are 

 thereby reduced more greatly, e.f^. increased plant cost 

 may save more in labour cost, and an increase in bad 

 castings may even be warranted by the great saving 

 of heat and labour due to working faster 



With regard to heat losses. Dr. Hering points ouf 

 that one of the first things to bear in mind in all 

 high-temperature thermal operations is that insulation 

 against heat loss is in practice at best verv poor; that 

 the ideal in this direction is the vacuum jacket of the 

 Dewar thermos bottle, but that this, unfortunatelv. is 

 impracticable for metal melting. Hence, so long as 

 the metal is hot, just so loner will this loss continue. 

 Heat losses, however, depend not only on the thermal 

 insulation, but quite as much also on the length of 

 time during which they take place, so that reducing 



