2o8 



NATURE 



{Jan. 13, 1876 



These accounts no doubt refer to the same meteor as that 

 observed at Hardwick. William F. Denning 



Tyndale House, Ashley Down, Bristol, Jan. 8 



Blowpipe Analysis 



Major Ross (Nature, vol. xiii. p. 186) does not appear to 

 have thought of the impurities his soda might contain in his test 

 for the presence of a sulphide. Had he done so he would pro- 

 bably have remembered that all soda (unless specially prepared 

 from sodium) contains traces of iron. This iron, on fusing with 

 the sulphide, forms ferrous sulphide, wliich, as is well known, is 

 soluble in fused sodium sulphide ; and on adding water to the 

 fused mass a black residue of ferrous sulphide remains behind. 



Again, he says "there can be no room to precipitate anything 

 in a drop of water ; " but surely this is erroneous. It is only a 

 question of degree. Under the same circumstances a precipitate 

 would be as certainly formed in a drop of water as in a gallon. 



If Major Ross were to make allowances for the ordinary im- 

 purities of commercial reagents, a little more confidence might 

 be placed in his tests. T. S. Humpidge 



Marine Aquaria 



While reading Mr, Wills's very suggestive article on Marine 

 Aquaria in your last issue, the following question suggested itself 

 to me : — Does not the " larger proportion of carbonic acid in the 

 lowest depths of the ocean " explain, at any rate partiallv, the 

 formation of the "abyssal red clay," which Prof. VVyville 

 Thomson has proved to occupy so laige a portion of the bed of 

 the Atlantic? 



"ISIany of the insoluble carbonates, and in particular those of 

 lime, magnesia, &c., may be dissolved to some extent by water, 

 charged with carbonic acid, and are deposited in a crystalline 

 form, as the gis slowly escapes from the fluid." (Miller's 

 " Chemistry.") 



That the presence of carbonic acid in the deep-water '\% one 

 cause of the decomposition of the shells of Mollusca, &c., I 

 think that there can hardly be a doubt. Whether it is sufficient 

 by itself to account for the whole phenomenon, I cannot presume 

 to decide. H J. "M'G. 



Bournemouth, Jan. 10 



The Glow-worm in Scotland 



Mr. J. Shaw's in'eresting note on the Glow-worm leads me 

 to remark that it is common about Loch Lomond, and recalls the 

 pleasant surpri-e with which I met one there, shining brilliantly 

 by the wayside, so late as tv.elve o'clock on a dark midsummer's 

 night. Wm. McLaurin 



London, Jan. 10 



Bryant and May's Safety Matches 



These matches are highly electrical, and if they be rubbed 

 ai'ainst glass and ebonite they ignite, especially if the electrics be 

 dry and warm. How far their ready ignition on amorphous 

 phosphorus is due to chemism or to electricity remains to be 

 proved. I am sorry I have not the opportunity just now to test 

 this point. W. H. Preece 



OUR ASTRONOMICAL COLUMN 

 The Minor Planet, No. 153.— This planet, dis- 

 covered by Palisa at Pola on Nov. 2, 1875, and which has 

 been named Hilda by Prof. Oppolzer, is found to have a 

 period of revolution considerably longer than any other 

 member of the group. In No. 39 of Prof, lietjen's 

 " Berlin Circular " is an orbit calculated by Dr. Schmidt, 

 which represents closely the observations to the end of 

 the year. It is as follows :— 



Epoch 1875, Nov. 22, at Berlin midnight. 



Mean anomaly 108= 30' 11" 



Longitude of perihelion ... 284 41 50 | jg--.Q 

 Longitude of ascending node 228 20 43 ) '•' 



Inclination to ecliptic ... 7 44 52 



Angle of excentricity ... 8 33 3 



Mean diurnal motion ... 452"'42i3 



The major semi-axis is'3'9474, and if we calculate ih 



distance of the comet from the orbit of Jupiter at the 

 aphelion passage, we find it o 864, the earth's mean dis- 

 tance from the sun being taken for unity, which is a much 

 closer approach to Jupiter's path than occurs with any 

 other of the minors. Themis, for instance, the motion of 

 which was investigated by Dr. Krueger, for determination 

 of the mass of Jupiter, does not approach that planet 

 within about i"5. More than one of the small planets 

 with the longer periods have large heliocentric latitude at 

 the aphelion point, and do not on that account approach 

 so near to the orbit of Jupiter as others with shorter 

 periods and somewhat greater excentricities, and having 

 the lines of nodes and apsides less divergent. Cybele in 

 aphelion is i"3i from the orbit of the great planet, 

 Freia \'2\, and Camilla, according to the rather uncertain 

 orbits yet available, r36. Hence, as suggested by Palisa, 

 his planet Hilda is well situated for further investigation 

 on the mass of Jupiter by the perturbations of the minor 

 planets ; it is well known, however, that this important 

 element in the solar system is now reduced within narrow 

 limits of uncertainty. 



The above orbit of Hilda is confirmed by another com- 

 puted by Herr Kiihnert of Vienna from a similar ex'ent of 

 observations. The period of revolution is about 2,865 

 days, or approaching eight years, contrasting strikingly 

 with the period of Flora, which is only 1,193 days, or 

 a little over 3.} years. 



Satellites of Uranus. — The following positions of 

 the brighter satellites of Uranus are derived as before 

 from Newcomb's Tables in the Appendix to the Wash- 

 ington Observations for 1873 ; they are for iih. 30m. P.M. 

 Greenwich time : — 



TiTANIA. ObEROK. 



Angle. Dist. Angle. Dist. 



Jan. 



The Great Comets of 1874 and 1680. — Now that 

 the orbit of the fine comei of 1874 (Coggia, April 17), 

 determined from the observations in the northern hemi- 

 sphere to the middle of July, has been shown by the 

 southern observations extending to October, to require 

 but small corrections, we may examine with confidence 

 the path of the comet about the passage of the descending 

 node, when it approached near to the orbit of Venus. 



Employing the elements calculated by Dr. Geelmuyden, 

 of the Observatory, Christiania, we have the following 

 results : — 



Heliocentric Heliocentric Diaance of Cornet 



Ecliptic Longitude. South Latitude. from Orbit of Venus. 



299° 45' 2° 17' 48" 0-003655 



299 48 2 24 38 0003181 



299 51 2 31 29 0-003323 



300 O 2 51 58 0006372 



Therefore, assuming the solar parallax 8''875, with 

 Clarke's semi-diameter of the earth's equator, the least 

 distance of the comet from the orbit of Venus is found to 

 have been 293,000 miles, or only about one-fourth greater 

 than the distance of the moon from the earth. 



A very celebrated comet, that of 1680, approached the 

 earth's orbit within even less than this distance. From 

 the definitive elements of Encke it would appear that in 

 92° 3''5 heHocentric longitude, just before traversing the 

 plane of the echptic, towards the south, the comet's dis- 



