556 



NA TURE 



[October 4, 1S94 



compound is a liquid of pleasant odour, reminding one at the 

 same time of ether and of weak ammonia. It reduces Fehling's 

 solution with great energy upon gently warming, and silver 

 nitrate in the cold. It vigorously attacks caoutchouc. Its 

 hydrochloride contains two molecules of hydrogen chloride, 

 and crystallises well in plates melting at l6o'. The symmetrical 

 di-ethyl hydrazine behaves in a most interesting manner with 

 certain oxidising agents, particularly mercuric oxide. The 

 yellow oxide reacts in a most violent manner, but the red oxide 

 affords a more manageable reaction ; the products are a large 

 quantity of mercury diethyl, IIs(C._.H. I., and a smaller quantity 

 of aroethane, C5Hj\ = N'C.jH.,. the elhyl analogue of the well- 

 known azobenzene. The symmetrical and unsymmetricil di- 

 ethyl hydrazines are clearly distinguished by their reactions 

 with nitrous acid, for while the latter yields di-elhylamine and 

 nitrous oxide, the former affords ethyl nitrite together with a 

 smaller quantity of a nitroso compound. 



The additions to the Zoological Socicly's Gardens during the 

 past week include two Bonnet Monkeys (Ma^acus sinicus, <J <5 ) 

 from India, presented respectively by Mr. Philip E. Morel and 

 Miss Ling ; a Common Maimoset {HafaU 

 iacchui) from Brazil, presented by Mr. A. 

 E. W. Burns ; a Brush-tailed Kangaroo 

 (Petrogak peniiillala, 9 ) from New South 

 Wales, presented by Lady Isabel Clayton ; 

 three Australian Cranes (Crus austra- 

 lajiana) from Australia, a Brown Crane 

 ( Grus canadensis) from North America, an 

 Indian White Crane {Cms leucogctancs) 

 from India, presented by Mr. E. W. 

 Marshall ; two Californian Quails (Colli- 

 fepla californica) from California, presented 

 by Mr. H. H. Howard Vyse ; a 

 Ground Hornblll (Bucorviis al'yssiniciis), 

 from Nyassaland, presented by Mr. H. H. 

 Johnston, CIS. ; three Pratincoles (C7/ar«>/<j 

 pratiucola), four Night IIerons(A[)v/;V<?ra.> 

 ^riseus), a Great Bustard (Otis tarda). 

 South European, presented by Lord Lil- 

 ford, three Dwarf Chameleons (Chamtc- 

 lean pumilus) from South Africa, presented 

 by Mr. C. Stonham ; two Cerastes \ipers 

 ( Vipera cerastes), two Egyptian Eryx (£;;j'.v 

 jaeulus), a Cliffords Snake (Zanieiiii 

 ctijordi) from Egypt, deposited ; .\ Si- 

 inonys Lizard ( Lacerla simonyi) from the 

 Island of lliero, Canaries, |>resenled by 



Mr. Sydney Croniplon ; a Deadly Snake ( Tri^jnoetphalus atrox) 

 from Trinidad, presented by Messrs. Mole and Urich ; an Axis 

 Deer (Cr;:'Kj axis), a Rufous Rat Kangaroo, Ilypiiprymnii' 

 riifesctns) born in the Gardens. 



What will most probably lead to a great advance in the deter- 

 mination of the positions of these radiant points, is the introduc- 

 tion of photography for recording permanently the visible tracks 

 in the sky. There may have been many attempts already for 

 photographing these trails, and the writer himself a few years 

 back, with an ordinary camera, w.as fortunate enough to catch nine 

 trails on the sensitive plate. The camer.\ being fixed and not 

 equatorially mounted, the star images were consequently curved 

 arcs, and not points. Even on this plate fairly accurate positions 

 of the trails could have been obtained. 



A somewhat unique instrument for locating the tracts of 

 meteors and their radiant points, has recently been consliucted 

 by Messrs. Warner and Swazey for the Vale University Obser- 

 vatory. The accompanying illustration of the instrument is 

 from Popular Astronomy for September. 



The illustration shows the polar axis of the " English " form 

 carrying a number of cameras. The axis is of a tubular form, 

 about twelve feet long, the ends working on pivots which are 

 capable of adjustment. The southern support is connected 

 with clockwork, while that at the northern end is supported 

 on a pillar in which are the driving weights in connection with 

 the clock by cords passing under the floor. On the declination 

 axis are lilted two arms which serve as supports to the cameras, 

 three cameras being on the eastern and three on the western 

 side. These cameras are so oriented that they take, in their 



OUR ASTRONOMICAL COLUMN. 



An iNSIKtMESr for PHOTOr-.RAlHI.NC METEORS, —Up to 

 the present lime meteoric astronomy has had little, if any, 

 instrumental equipment to further its development, the nature 

 of the phenomena rendering simple naked eye observations the 

 only available means of research. It is true that even now we 

 know of a very considerable number of radiant points, and what 

 i, more, we have been able to note the daily movemcnls of some 

 uf these in the heavens ; but (his knowledge has only been 

 gained by the great patience and perseverance of astronomers, 

 the most notable being Mr. W. F. Denning. With a Ihorougli 

 knowledge o( the conslcllalions, a good globe or slar-map, and 

 an accurate eye, he has been able to plot down (rack after 

 track of these travellers through space, deducing from their 

 paths (he points in the heavens from which they are coming. 



NO. I 30 1, VOL. 50] 



respective fields, adjoining portions of the sky, so that altogethei 

 they cover a very large area. The instrument is supplieil 

 with slow motions, both in right ascension and declination. 

 and the clockwork has an electric control. Whether satis 

 factory results have yel been obtained, one cannot .say, but the 

 apparatus was intended to he used for the Perseid swarnr of 

 October last. 



SUN-SPOT OBSERVATIONS AT THE 

 PO TSDA M OIISER I 'A Tt >R ] '. 



TN the publications of the " Potsdam Aslrophysical Observa- 

 tions," Dr. Sporer has previously (No. 17) presented u- 

 wilh ihe observations of the sun-spots for the years 1880 ti 

 18S4. The most recent addition to these records will 1< 

 found in No. 32, in which arc collected the sun-spot ob 

 scrvations for ihe years 1S85 to 1S93. The observations them- 

 selves are given in all details, being grouped together with 

 regard to the period of rotation. These are followed by a 

 brief discussion, from which these notes and extracts have been 

 made. 

 The following (able, bringing together the results relative lo 



