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NATURE 



[May 26, 1898 



The additions to the Zoological Society's Gardens during the 

 past week include a Guinea Baboon {Cynocepkalus sthinx, <J ) 

 from West Africa, presented by Captain H. de la Cour Travers ; 

 a Vervet Monkey (Cercopithecus lalandii, i ) from South Africa, 

 presented by Mr. C. J. Barratt ; a Common Raccoon {Procyon 

 lotor) from North America, presented by Mr. A. D. Jenkins ; 

 a Reindeer {Rangifer\ tarandiis, S ) from Newfoundland, pre- 

 sented by the Hon. M. A. Bourke, H.M.S. Cordelia; a 

 Common Guillemot (Lomvia troile), British, presented by Mr. 

 Ernest Home ; a Seven-banded Snake ( Tropidonottis seplem- 

 vittaius) from North America, presented by Mr. James Meldrum ; 

 a Barbary Ape [Macacus iiiniis, 6 ) from North Africa, a Red- 

 River Hog {Potamocharus penicillatus) from West Africa, a 

 Beccaris Cassowary {Casuarius beccarii) from New Guinea, two 

 Orange-winged Amazons {Ckrysotis ainazonica), two Blue- 

 fronted Amazons {Ckrysotis cestiva) from South America, de- 

 posited ; a Leucoryx Antelope ( Oryx leucoryx, S ) from North 

 Africa, purchased ; a Red-winged Parrakeet {Ptisles erythro- 

 pterus, 9 ), a Long-billed Butcher-Crow {Barita destructor) from 

 Australia, received in exchange ; two Japanese Deer [Cervus 

 sika, (J ? ), three Shaw's Gerbilles {Gerbillus shawi), born in 

 the Gardens. 



OUR ASTRONOMICAL COLUMN. 



Astronomical Occurrences in June : — 

 June 3. 6h. 34m. to gh. 25m. Transit of Jupiter's Sat. HI. 

 4. 8h. Eastern elongation of Saturn's Sat. Japetus. 

 4. 8h. lom. to 9h iim. Occultation of A Ophiuchi 

 (mag. 47) by the moon. 



4. I5h. 43m. to i6h. 34m. Occultation of B.A.C. 5909 



(mag. 6 '2) by the moon. 



5. loh. 15m. to iih. 22m. Occultation of A Sagittarii 



(mag. 3 "I ) by the moon. 



9. iih. 31m. to I2h. 23m. Occultation of B.A.C. 7804 

 (mag. 61) by the moon. 



9. Saturn. Outer minor axis of outer ring, 18" '62. 

 10. loh. 23m. to I3h. i6m. Transit of Jupiter's Sat. IH. 

 12. I9h. Neptune in conjunction with the sun. 

 15. Venus. Illuminated portion of disc 0853. 

 15. Mars. ,, ,, ,, o'9i9. 



15. Jupiter. Polar diameter, 34" -8. 

 15. Saturn. „ ,, i7"o. 



17. 9h. 45m. to iih. 23m. Transit of Jupiter's Sat. IV. 



18. loh. 59ni. Minimum of )3 Persei (Algol). 



23. 5h. Inferior conjunction of Saturn's Sat. Japetus. 

 29. Saturn. Outer minor axis of outer ring, 18" "33. 

 The transit of Jupiter's fourth satellite on June 17 is the only 

 one visible during 1898. 



Blurring Aberration in the TELEScofn:. — Some 

 time ago we referred in this journal (December 30, 1897, p. 200) 

 to a communication by Prof. Schseberle which pointed out that 

 the optical image of a celestial object, formed in the focus of a 

 reflecting telescope of great angular aperture, is possessed of 

 errors of definition which arise from a cause hitherto unrecognised 

 by mathematical and practical opticians. The main results of 

 this paper briefly summed up are as follows : — First, that the 

 focal plans of a curved reflecting surface for parallel rays im- 

 pinging thereon is situated upon the axis, half-way between the 

 centre of curvature and the reflecting surface itself ; and, second, 

 that the plane of the image formed by each small patch of the 

 converging surface tends to lie at right angles to the path of the 

 focussed rays, so that the images formed from every minute 

 portion of the reflecting surface, while their centres may coincide 

 on the axis of the telescope, all tilt from the focal plane directly 

 as the extreme of aperture is approached, or as the focal point is 

 shifted from the axis. In the Transactions of the Astronomical 

 and Physical Society of Toronto for 1897, Mr. J. R. Collins, in 

 referring to Prof Schoeberle's paper, points out that it is possible 

 to so proportion the curvature's of the reflecting surfaces of the 

 Gregorian form of reflecting telescope (where the image is formed 

 by the large reflector in front of the small concave mirror, and 

 the light ii thrown back to a focus on the axis through an open- 

 ing in the centre of the large reflector to the eye-piece), as to 



NO 1 49 I, VOL. 58] 



completely correct the tilt and want of uniformity of dimensions 

 of the components of the compound image, that it may reach the 

 front of the eye-piece entirely freed from these defects. It may 

 be remarked that the tilting of the image not only occurs in the 

 case of the reflector, but in that of the refractor also, the effect 

 in the latter case being twice as great as that in the former. In 

 fact, the Schaeberle aberration is a defect that exists in all forms 

 or combinations of lenses, and must, therefore, be taken into 

 account if we wish to attain maximum efficiency in definition. 



Photography by the Aurora Borealis.— Mr. J. E. 

 Turner, writing in The Amateur Photographer for May 6, 

 describes a unique photograph which he has obtained. It 

 seems that on April 15 Gourock was visited by a very vivid 

 display of the aurora borealis, which lasted from 10 to midnight. 

 The moon having set at 9.13 p.m. and not rising again until 

 4.5 a.m. the next morning, he thought it might be possible to 

 get a photograph merely by the light of the aurora borealis, and 

 he consequently exposed a plate towards the northern horizon, 

 giving an exposure of only two minutes with f/8 and a Paget 

 xxxxx. plate. The negative, when developed with a very weak 

 pyro and ammonia developer for about one hour, came out well 

 and showed clearly the nearest land that was three miles distant, 

 together with the houses, which were clearly defined, besides 

 numerous trees in the foreground. The photograph is reproduced 

 in the above-named journal. It is not mentioned whether an 

 impress of the aurora itself was obtained, but only the statement : 

 " the stars also nearest the zenith are faintly seen, the light from 

 the aurora, of course, obscuring them." 



Mr. Tebbutt's Observatory.— The Report of Mr. Teb- 

 butt's Observatory at Windsor, New South Wales, for the year 

 1897, shows that the number of observations made is up to the 

 standard of former years. The 8-inch equatorial was employed 

 for observing occultations of stars by the moon, 134 phases being 

 noted, and numerous minor planets. Perrine's comet was also 

 diligently watched for several weeks, and many variable stars 

 arid phenomena of Jupiter's satellites observed. The meteoro- 

 logical observations have been as usual regularly made. Seven 

 years' meteorological observations are now in hand, and will be 

 soon published ; and when this is completed, there will be a 

 period of thirty-five years of published data which will be in- 

 valuable for investigating the local climate. In consequence ot 

 recent local legislation, Mr. Tebbutt writes : " Anotice was sent 

 to the Minister of Public Instruction on October 1 1 last, that it 

 was intended at the close of the year to discontinue the meteoro- 

 logical department, and the hopevvas expressed that the Govern- 

 ment would see fit to continue the work at its own expense. A 

 reply was received stating that the work would be continued 

 ... at the Hawkesbury Agricultural College, about four miles 

 west of the Observatory." Such an arrangement as this was 

 evidently very satisfactory, for it would have been a crime to have 

 suddenly broken the continuity of what must be valuable data 

 for investigating the climatic conditions of New South Wales. 

 " After due inquiry," as Mr. Tebbutt further states, "at the 

 close of the year, it turned out, however, that provision had not 

 been made for continuing the Windsor meteorological work in all 

 its departments. It is proposed to continue at this oijservatory 

 observations of the daily rainfall by the two gauges, and to 

 secure the monthly maximum and minimum air temperatures." 

 We hope that the Government will not be long in seeing that 

 due attention must be paid to the question of meteorology in 

 New South Wales, and that, after private enterprise has carried 

 on the work for so many years, it becomes a duty to see that a 

 breach in the continuity of the observations is not made through 

 lack of funds. 



SOME NEW STUDIES IN KATHODE AND 

 RONTGEN RAD I A TIONS> 



T^HE researches of Crookes, Lenard, and Rontgen have given 

 to man a new eye ; they have, perhaps, also given to nature 

 a new light ; they have certainly given to science more than 

 one new problem. A vacuum tube may appear but a simple 

 piece of apparatus ; but were we acquainted in their entirety 

 with the secrets that it contains, we should know much at present 

 utterly unknown, not only as regards electrical action, but also 

 in reference to the fundamental constitution of matter, and the 



1 Abstract of Friday evening discourse delivered at the Royal Institution 

 on Febiuary 4, by Alan A. Campbell Swinton. 



