566 



NA TURK 



[Al'KIL 13, I 



1 



899 f 



ductivityand similar measurements, the autJiors think that the 

 Ostwald thermostat bath is still the safest and most convenient 

 appliance for preserving a constant temperature in the labor- 

 atory, the baths of "melting" crystals finding their greatest 

 use in the standardising of thermometers at fixed points. 



The additions to the Zoological Society's Gardens during the 

 past week include a Rhesus Monkey [Macaciis r/usiis, S ), from 

 India, presented by Mr. David M. Greig ; two Western Pin- 

 tailed Sand Grouse (Ptcrocks pyrenaica) from Spain, deposited ; 

 four Black-tailed Hawfinches (Coccothranstes me/aniinis) iiom 

 Japan ; a Lapwing ( VaneUiis vulgaris), European, purchased. 



OUR ASTRONOMICAL COLUMN. 



Comet 1899 a (Swift). — The unfavourable conditions in 

 England appear to have prevented any observations of this 

 comet, but on the continent it has been frequently seen. From 

 a detailed list of all the recorded observations given in Asl. 

 Nach. (Bd. 149, No. 3554), we see that the reported presence 

 of a central condensation is confirmed. Most of the observers 

 agree in estimating the magnitude as about 6'5, or just visible 

 to the naked eye. Prof. Max Wolf says that it was quite bright 

 in the finder, and easily seen with the naked eye when guided 

 to the correct place by the telescope. With a 6-inch telescope 

 a short tail was distinctly visible. 



The comet is now very near the sun, but under favourable 

 conditions may possibly be seen with the help of the following 

 extended ephemeris : — 



oh. Berlin Mean Time. 

 1809. R.A. Decl. Br. 



In the beginning of May, however, it is likely that the comet 

 will be easy of observation in the early morning, as it will 

 rapidly recede from the sun after perihelion passage. 



Tuttle's Comet (1899 /*).^The previous ephemeris given 

 was based on data obtained in 1885 ; but successful observations, 

 obtained at Heidelberg, Lick and Konigsberg, have enabled 

 Herr ]. Rahts to recompute the elements and furnish a more 

 accurate ephemeris, which he has communicated to Ast. Nach. 

 (Bd. 149, No. 3555). 



Elements. 

 T = 1899, May 4'S Berlin Mean Time. 



i-8o 



New Star Catalogue. — The eighth volume of the "Astro- 

 nomical Observations and Researches made at Dunsink," the 

 observatory of Trinity College, Dublin, contains a catalogue of 

 the mean places of IIOI stars, together with the separate results 

 of 4022 observations of right ascension and 3999 observations 

 of declination, the range of declination being from - 28° to 

 -f So". 



The olKervations were made with the Pistor and Martin's 

 meridian circle by Mr. Charles Martin, under the direction of 



NO. 1537, VOL. 59] 



Prof. A. A. Rambaut, then Astronomer Royal for Ireland, 

 during the period 1896, March 16, to 1897, July 17. All the 

 places are brought up tu epoch 1 900, and the probable error is 

 about ± 0032SS. in R.A., jand + o""48o in Decl. A useful 

 feature of the catalogue is the inclusion of the corresponding 

 numbers denoting the various stars in other catalogues in vogue, 

 viz. Bradley's, Piazzi's, and the B.A.C. , and various others, so 

 that cross references are readily seen. 



The Si'.n's Heat. — Mr. A. S. Chessin, in a communication 

 to the Astronomical Journal, vol. xix. No. 456, relating to Dr. 

 See's article in .-Isl. "jfour., No. 455, noticed on p. 350 of the 

 current volume, writes as follows : — 



" Allow me to observe with regard to Dr. See's 'remark- 

 able ' law, which he discusses at length in the last number of 

 the Journal, that it is derived by the author with a superb 

 neglect of the principles of thermodynamics. The last stage of 

 the ' proof is especially curious, as the assertion that T,, must 



be multiplied by -^ in order to preserve the equilibrium, is 



nothing else than an assumption of that very ' law ' which Dr. 

 See proposes to derive." 



ALLO YS. 



I^HE fifth Report, by Sir William Roberts- Austen, to ihe 

 Alloys Research Committee of the Institution of Mechan- 

 ical Engineers contains some details of much scientific interest. 

 The system of taking cooling curves of n.etals and alloys, 

 originated by the author of the Report, is now well known, but 

 in the present Report he has indicated a method for obtaining 

 curves of extraordinary delicacy. An ordinary thermo-junction 

 of platinum and j.latinum iridium wires is placed within the 

 mass of metal which is heated in a vacuous lube, and allowed to 

 cool from a bright red heat. The result, in the case of iron, is 



that as the mass cools down there are several points at which 

 heat is evolved. In the curve of iron of a high degree of purity 

 only two such points have hitherto been detected, one at about 

 890° and the other at 760°. Both of these have been supposed 

 to represent allotropic changes in the metal, and the lower one 

 (at 760°) is that at which the magnetic properties of the iron 

 change. In ordinary cooling curves, however, both these points 

 have been indicated by little more than a change in direction of 

 the curves. By adopting the following method curves of great 

 delicacy have been obtained, and the result is that the old 



J*frcviau» ThAo 



changes in dirtctiim of the curves in the case of iron, have been 

 developed into large prominences and, moreover, new points in 

 the cooling curves, have been discovered. 



The following is the new method, of which a very brief de- 

 scription will be suHicient. In the ordinary method, the twisted 

 end of the thermo-junction A (Kig 1) is pl.iced in the heated 

 mass of metal 11 under examination, and its free ends are con- 

 nected with the galvanometer o. In the new method (Kig 2) 

 two thermo-junctions, A and A„ are employed. One of tnese 



