January 5, 1899] 



NATURE 



23: 



outwards by a similar process, so that there is a continuous 

 transference of oxygen by a sort of Grotthus chain of unstable 

 copper oxide molecules. This view is in harmony with the fact 

 that cupric oxide, the most easily reducible of the oxides investi- 

 gated, is the one which parts with its occluded oxygen most 

 easily, at the same time obstinately retaining the nitrogen, whilst 

 the oxides of zinc and magnesium, being more stable, retain the 

 oxygen persistently. It was found that the electrical conduc- 

 tivity of copper oxide was much increased at a temperature 

 approaching redness, whilst that of zinc oxide was much less 

 increased, and that of magnesium oxide not at all. This would 

 be explained by the copper oxide being to a certain extent 

 dissociated by heat, and permitting of some metallic conduc- 

 tion. Cupric oxide was found to give up oxygen steadily when 

 heated in vacuo to 790°> cuprous oxide being found in the 

 residue. 



The additions to the Zoological Society's Gardens during the 

 past week include a Rhesus Monkey (Macactis rhesus, 9 ) from 

 India, presented by Mr. A. Urban Smith ; six Snow Buntings 

 (Plectro/ikanax nivalis), Europein, purchased ; three Grey 

 Squirrels (Siiurtis citiereus) from North America, deposited ; a 

 Great Eagle Owl [Bubo maxiiiiiis), bred in the Gardens. 



Errata. — In the necrology of Prof. Allnian, p. 202, line iS, 

 delete "Regius"; p. 204, line 37, for " Grumera " read 

 " Gunnera." 



OUR ASTRONOMICAL COLUMN. 



Comet Chase. — The following ephemeris of Comet Chase is 

 a continuation of that which we have previously published from 

 Herr J. Moller's computation 



Jan. 



Planet Witt (DO 189S).— .\lthough only of the twelfth 

 magnitude, planet Witt should be closely followed and good 

 positions measured as opportunities afford. The accompanying 

 ephemeris for the coming fortnight will prove useful to those 

 whose instruments are large enough to follow this interesting 

 body. 



Berlin !\Iidni\;ht. 

 1898. R.A. Dec. 



The above ephemeris. calculated by Dr. E. Millosevich (Aslr. 

 Nachr., 3532), requires, according to an observation by Dr. 

 Ceriilli, a correction of about - 5s. in R A., and - o'-3 in 

 declination. 



Astronomical Photogramiy w ith S.mall Instruments. 

 — The earnest worker, even with only small means at his dis- 

 posal, may perform important work in astronomy by the aid of 

 lenses of comparatively small aperture. The great advances 

 made in the sensitiveness of dry plates helps us now to photo- 

 graph quite easily objects which formerly presented a great 

 difficulty. 



By replacing the eyepiece of a good telescope with a small 

 camera, with a suitable positive or negative lens, very useful 

 work can be done, although the scale of magnification need not 

 be very great. The employment of a negative lens makes the 

 instrument more convenient for use, as a shorter telescope tube 

 can be utilised. 



One great function of photographs of celestial objects is to 

 record changes in the appearance of bodies or regions studied. 

 In the case of the former large images are required, and the photo- 

 telescopes are the most suitable ; in the latter, large fields, but 

 not necessarily very large magnification, are required for many 

 purposes of great interest. In the Photographische Correspondeiiz. 

 Herr P. Zschokke points out in an interesting article the useful 

 viork an amateur can accomplish by means of small instruments, 

 and gives an interesting table showing the relative sizes of aper- 

 tures, focal lengths of objectives, focal lengths of combinations, 

 &c. Since, in this class of instrument, the size of the diameter 

 of the image formed is the main point, we give below the table 

 containing these values, which has been reproduced in the 

 Brilish Journal of Photography (December 23, 189S). All the 

 figures in the following columns refer to millimetres. 



perture. f.o':"? °f 

 objective. 



61 ... 730 



81 1218 



108 .. 1624 



135 1949 



•35 ■ 1353 



162 ... 2599 



162 ... 2599 



Focus of 

 tele-ptioto 



S370 

 8060 

 . 1 1370 

 16115 

 16115 

 32230 

 24170 



Entire length Di.imetei 



of image of < 



telescope. or moon 



980 ... 50 



1350 75 



i960 108 



2365 . 150 



iSoo ... 150 



3510 . 300 



3155 ■■ 225 



NO. 1523. VOL. 59] 



\ New Variable in Cassiopeia.— Dr. T. D. Anderson, 

 writing in the Astr. Nachr. (No. 3533), states that the star 

 which has the position for 1855, R.A. 23h. 37'5m., and 

 Decl. + 55° 45', is a hitherto unnoticed variable. This star, 

 which is not recorded in the BD, was first seen by Dr. Ander- 

 son in the beginning of 1897, and was then only 0'2 magnitudes 

 fainter than + 55'-3007, the magnitude of which was then fairly 

 estimated as 9-0. In September 23 of the same year the star 

 was found missing, although another star of magnitude 10-3 

 could be easily seen 3' to the north of the missing star. Sub- 

 sequent searches failed to pick up the same star again ; and Dr. 

 .■\nderson, coming to the conclusion that the object was probably 

 a Nova, only examined the region very occasionally. 



Last month, however, on the 5th, he again examined the 

 region, and at last found the object of his search. At this time 

 it excelled in brilliancy its neighbour of magnitude 10-3 by as 

 much as it was itself surpassed by BD + 55°'3007. 



Observations of o Orionis. — Mr. R. T. A. Innes, writing 

 from the Cape Observatory (Astr. Nachr., 3533), mentions that 

 he has been observing a Orionis (Betelgeuze) on several even- 

 ings, and the star was found to be only slightly brighter than 

 Alilebaran. Last season, as Mr. Innes states, Betelgeuze was 

 twice as bright as Aldebaran, which is its ordinary state. From 

 this observation it may be concluded that one of the irregular 

 minima of Betelgeuze is approaching. 



PRIZES PROPOSED BY THE PARIS ACADEMY 



OE SCIENCES FOR 1899. 

 'pHE following are the prize subjects proposed by the French 

 Academy of Sciences for the present year. 

 The Bordin Prize (3000 fr. ) for a study of the q^tions re- 

 lating to the determination, properties, and application of 

 systems of orthogonal curvilinear coordinates of « variables, 

 indicating particularly, in as precise a manner as possible, the 

 degree of generality of these systems ; the Francorur Prize ( 1000 

 fr.) and the Poncelet Prize (2000 fr.), for useful work in the field 

 of pure and applied mathematics. In Mechanics is ofi'ered the 

 Extraordinary Prize of 6000 francs, for any invention increasing 

 the etticiency of the French naval forces ; the Montyon Prize 

 (700 fr. ), for the invention or improvement of instruments useful 

 to the progress of agriculture or the mechanical arts ; the Plumey 

 Prize (2500 fr. ), for any invention contributing to the progress 

 01 steam navigation ; the Tourneyron Prize, for an improvement 

 in any point of the theory of pumps. In Astronomy, the Lalande 

 Prize (540 fr, ), for the most interesting or useful astronomical 

 observation made during the year: the Valz Prize (460 fr. ) 

 for astrononomical work. In Physics, the La Caze Prize 

 (10,000 fr. ). In Statistics, the Montyon Prize (500 fr. ). In 

 Chemistry, the Jecker Prize (10,000 fr.) for discoveries in 

 organic chemistry; the Cahours Prize (3000 fr. ) for the 

 encouragement of research in young chemists already known by 

 their published work ; and a La Caze Prize of 10,000 fr. In 

 Mineralogy and Geology, the Delesse Prize (1400 Ir.), and the 



