December 15, 1898] 



NA TURE 



in contact with dilute mineral acids caused notable decom- 

 position of the hydrazoic acid. A large number of metallic 

 salts were prepared and analysed, and in every case the salts 

 were found to be anhydrous. The metallic derivatives differ 

 considerably in their explosive properties. Thus, of the deriv- 

 atives containing the metals of the alkalis and alkaline earths 

 (with thallium), lithium nitride is the only one exploding 

 violently on heating, and thallium nitride the only one de- 

 tonating when struck on an anvil. The action of heat upon the 

 nitrides of these two groups is very remarkable, as when small 

 quantities of the nitride are heated carefully in thin glass tubes, 

 decomposition takes place quietly, nitrogen being evolved, and 

 ihe pure metal left behind ; this being, as the authors point 

 out, much the easiest method of preparing small quantities of 

 barium, strontium, and calcium. 



The additions to the Zoological Society's Gardens during the 

 past week include an Egyptian Jerboa (Dipus aegyptiiis) from 

 North Africa, presented by Miss Da Costa ; an African Buzzard 

 {Biiieo desertoruin^, an Iceland TaAconiffiernfalco tslaiidiis), cap- 

 tured in the Red Sea, presented by Captain E. W. Burnett ; a 

 Peregrine Falcon (Falco peregrinits), captured in the Red Sea, 

 presented by Captain Bear ; a Rough-keeled Snake {Dasypeltis 

 scabra) from South Africa, presented by Mr. H. Oakley ; 

 two Scops Owls {Scops ,^111), South European, deposited ; a 

 Brazilian Tapir (Tapirus ainericaniis,^ ) from the Upper 

 Amazons, two Common Rattlesnakes (Crolaliis diirissiis) from 

 North America, purchased ; an Axis Deer ( Cennis axis), born 

 in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



The GEMlNins. — For the greater part of the evenings of t+ie 

 loth, nth and 12th of this month, clouds prevented observ- 

 ations of the Geminids in London. Late on the night of the 

 I2th, however, when the sky became to some extent clear, a 

 brief watch of an hour, from iih. 30m. p.m. to I2h. 30m. a.m. 

 G.ALT., disclosed the fact that these meteors were very much 

 en evidenu. Between iih. 30m. and I2h. 5m. no less than 

 twenty-four Geminiils were observed, four of which were of great 

 brilliancy and brighter than a first magnitude star. The direction 

 of observation was necessarily restricted towards the north-west. 

 Curiously enough, a further watch from that time until I2h. 

 30m. was only rewarded by the observation of one meteor, and 

 that not a Gerainid, which gave one the impression that the 

 shower had terminated. Clouds prevented further observation. 

 Whether the shower was more brilliant earlier in the evening 

 cannot, so far as this place of observation is concerned, be stated. 

 Another observer, Mr. W. E. Rolston, of the Royal College of 

 Science, South Kensington, was also surprised at what appeared 

 to be quite a shower of meteors on the same evening. He 

 recorded the appearance of several meteors during the interval 

 Iih. 15m. p.m. to I2h. 20m. a.m. G.M.T. , one of which, as he 

 describes, " an exceptionally long and bright one, leaving a long 

 trail of reddish sparks, which lasted for about two seconds." 

 The same observer also mapped nine true Geminids on the night 

 of the 9th. 



Co.MET Chase. — Using the same elements as those we 

 published in our last number, the following is the ephemeris for 

 the current week. 



Ephemeris for Berlin Mean Miditighl. 

 1898. R.A. (app.) Decl (app.) Br. 



Dec. 14 ... 10 47 51 



,, 16 ... 49 51 



,, 18 ... 51 44 



,, 20 ... 53 31 



,, 22 ... 10 55 II 



+ 25 49 J 

 26 6'o 

 26 23-4 

 26 41-3 



+ 2(s 598 



1-39 



The comet is thus still in the constellation of Leo, and is 

 situated approximately between 54 and 57 Leonis. It is now 

 brighter than it was at the time of its discovery. Prof. E. 

 Weiss thinks that it may be identical with 1867 I. 



It is interes'ing to remark that the comet was discovered 



NO. 1520, VOL. 59] 



photographically near the radiant point of the Leonid meteor 

 swarm. Four other photographs taken — two at the Yale, and 

 two at the Harvard observatories — have corroborated its 

 presence. 



The Total Solar Eclipse of January 22, 1S98. — We 

 have received from the Survey of India Department the report 

 on the observations made at Dumraon, Pulgaon, and Sahdol 

 during the recent solar eclipse. The report is divided into three 

 sections, each section giving an account of the arrangements 

 and observations made at the three different stations. The first, 

 somewhat necessarily brief, is written by Mr. T. A. Pope, 

 -Assistant Surveyor-General, who had charge of a three-inch 

 photographic doublet. With this instrument an excellent series 

 of plates of the corona was obtained, one of which is reproduced 

 as frontispiece to the present volume. The Pulgaon report, by 

 Captain G. P. Lenox Conyngham, R. E., contains an interesting 

 and well illustrated description of the camp, and the programme 

 which the party had before them. Mr. Newall and Captain 

 Hills, it will be remembered, occupied this station, and received 

 valuable assistance from the officers and others present. The 

 report on the observations at Sahdol, by Major .S. G. Burrard, 

 R.E. , is somewhat more voluminous than the two preceding. 

 In addition to a general account of the arrangements as regards 

 the camp distribution and the preparatory work of the observers, 

 such results as could be immediately deduced are given. Thus, 

 for instance, we have a comparison betsveen the temperature 

 curves obtained on the actual and following day of the eclipse, 

 showing clearly the drop from the time of first contact to about 

 half an hour after totality, and the subsequent rapid rise. The 

 large assembly at Sahdol made it possible to organise a party to 

 make sketches of the corona. This was done, with the result 

 that we have here thirty-one facsimiles of the hand-drawings 

 made. After an examination of these sketches, we can truthfully 

 remark, with Major Burrard, that " the accordance between these 

 drawings is more remarkable than their discrepancies." The 

 remaining portion of the report is devoted to a brief summary of 

 the Hindu method of eclipse prediction, a chapter on future total 

 solar eclipses in India, with twelve charts of tracts of past and 

 future solar eclipses, and lastly to the answers to a series of 

 questions concerning the corona and the attendant phenomena. 



The volume, which is published under the direction of Major- 

 General C. Strahan, R.E., the Surveyor-General of India, is 

 very well illustrated, and should serve as a useful guide and 

 source of valuable information for future eclipse expeditions. 



November Meteors. — The Harvard College Circular 

 (No. 35), which has just come to hand, describes in a brief 

 manner an account of the preparations for observing the Leonid 

 shower in America, and the preliminary results obtained. It 

 will be remembered that last year Prof. E. C. Pickering 

 organised a large staff of observers not only to make visual 

 observations, but to record, if possible, their trails and spectra 

 photographically. This year the organisation was even more 

 complete, and stations were selected all round the earth in 

 order that the number of visible meteors might be counted 

 during the entire period that the earth passed through the 

 swarm. The present Circular deals with the observations made 

 at Cambridge (U.S. .A.) and Providence, the reports from other 

 stations not having yet arrived. 



At the former town the night of the 13th was cloudy, but the 

 14th was clear. Thirty persons at the observator)' recorded 

 Sod meteors, not including duplicates, the maximum number 

 having occurred at 3 o'clock in the morning, when 61 meteors 

 east of the meridian were counted in thirty minutes. No less 

 than 227 trails of eighty different meteors within 30° of the 

 radiant were charted. At Providence the vicinity of the 

 radiant point was continuously w-atched by at least ten observers, 

 and 400 meteors were seen. Prof Pickering chose this station 

 (which is forty miles south of Cambridge) for visual deter- 

 minations of parallax. 



As regards the success of photography for this work, the 

 results obtained seem very promising. Ninety-six photographs 

 were taken at Cambridge with the Draper telescopes, and eleven 

 with smaller instruments. Not only were photographic doublets 

 employed, but prisms were utilised ; but these, unfortunately, 

 failed to give any record. By means of the doublets thirty-one 

 trails of eight different meteors were photographed, three of 

 which appeared on one plate. Four meteors w ere photographed 

 at both stations, so that the parallax can be obtained photo- 

 graphically. A preliminary determination of the radiant point 



