June i i, 1896J 



NA TURE 



'3/ 



Dr. F. Katzer; some curious geological effects produced by 

 wind-borne sand, by Prof. J. N. Woldfich ; the anatomy and 

 <levelopment of the brain of vertebrates, by F. K. Studnicka ; 

 ihe development of Stylomatophora, by J. F. Babor ; determina- 

 tion of the altitude of the celestial pole by means of photography, 

 by. Prof. V. Laska ; on Baculus elongatus (Lubbock) and 

 Leriiaa bramkialis, a contribution to the anatomy of Lern;vada;, 

 V)y A. Mrazek ; studies of isopoda, by B. Nemec ; on electro- 

 lytic superoxide of silver, by Dr. O. Sulc ; studies of the 

 CoccidiV, by K. Sulc (this paper is summarised in English) ; 

 the histology and histogenesis of the spinal cord, by Dr. F. 

 K. Studnicka ; and new vertebrates from the Permian formation 

 of Bohemia, by Prof. A. Fritsch. 



The additions to the Zoological Society's Gardens during the 

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

 India, presented by Mrs. Bouveri ; two Slow Lorises (Nycticebus 



lardigradus], a Toad (Bufo aspci) from Penang, a Roseate 



Cockatoo (Caca/iia rosenapilla) from Australia, a Lesser Sulphur- 

 crested Cockatoo {Caca/iia sulphurea) from Moluccas, two 

 Spinose Land Emys {Gcoiityda spinosa), a Black-spotted Toad 

 (Bufo melanosti(lus) from Singapore, presented by Mr. Stanley 

 S. Flower ; two Hairy Armadillos (Dasypus villosus) from 

 Uruguay, presented by Messrs. FitzIIerbert, Bros. ; a Coati 

 (A'asua ru/a) from South America, presented by Mr. Ernest 

 Brocklehurst ; two Herring Gulls (Larus argen/atus), two 

 Black-headed Gulls (Larus ridihundiis) British, presented by 

 Baron Ferdinand de Rothschild ; a Javan Porcupine {Hystrix 

 javaiiica., white var. ) from Java, a Leopard Tortoise ( Tesiudo 

 pardalis), a Xatal Python {Python schtc, var. natatcnsis) from 

 South Africa, a Cunningham's Skink (Egcrnia cunninghaini) 

 from Australia, deposited ; a Japanese Deer (Cervus sika, (5 ), a 

 Red Deer ( C^;-z'Kx e/aphus, 9 ), two Thars [Capra jemlaica, 9 9), 

 a Huanaco {Lama huanacos, <J ), born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 

 OccuLTATiox OF Jupiter. — On the evening of June 14 there 

 will be an occultation of Jupiter and his satellites. The planet 

 will disappear at gh. 52m. G.M.T. at an angle of 113° from the 

 north point towards the east, and reappear at loh. 43m. at the 

 position angle 293". The moon will be about three and a half 

 (lays old, but as it will set at loh. 56ni. the reappearance will 

 occur under unfavourable conditions of observation. The sun 

 will pass below the horizon of Greenwich at Sh. i6m. on 

 the 14th. 



Comet Swift. — The following elements for comet Swift, 

 1896, have been derived by F. Bidschof {Asl. Nai/i., No. 

 5356)- 



T=i896 April 17-68237 (Berlin M.T.) 



"-= "i 43 55".? I 

 4? =178 15 2S-I ,tS96'o 

 '■ = 55 r^ 42-S J 

 log </ =9753076 

 The following is a short ephemeris, the unit of brightness 

 being that on April 19 : — 



R..'^. 



h. 



Bright- 



June II ... 22 17 17 



15 ... 21 52 31 



19 ■.. 21 29 5 



23 ... 21 7 20 



27 ... 204729 



July I ... 20 29 38 



4-72 43 .. 0-05 



72 21 ... 0-05 



71 46 ... 0'04 



70 57 ••■ 003 



69 57 ... 003 



-(-68 45 ... 0-03 



The last published observation is that of Dr. Engelhardt on 

 May II {Ast. Nach., No. 3353), when the comet was reported 

 "faint." 



Spots and Markings o.n J niTER.— During the past 

 seventeen years Prof. Hough, of the Dearborn Observatory, 

 has made an almost unbroken series of observations of the mark- 



NO. 1389, VOL. 54] 



ings of Jupiter, with the special aim of studying the phenomena 

 by means of micrometrical measures of size and position, rather 

 than by sketches. He considers that for the proper interpre- 

 tation of the changes taking place, such measurements, extend- 

 ing over a long period of time, are absolutely necessary, while 

 the study of latitude variations is likely to lead to results as 

 important as those of rotation period (Ast. Nach., No. 3354). 

 Photographs have been regarded as capable of giving results as 

 accurate as micrometric measures in the telescope, but long ex- 

 perience has led Prof. Hough to doubt this conclusion. Not- 

 withstanding its varying visibility, the .size and shape of the 

 great red spot have changed very little since 1S79, though 

 during recent years it was possibly i" shorter than when it was 

 most conspicuous. The very slight change in the latitude of 

 the spot during the last seventeen years seems to indicate that 

 this object is the most stable of any of the markings. The 

 average length of the spot, reduced to mean distance, has been 

 II "■61 or 37°'2. Measures of the equatorial belt and of several 

 spots are also given, and it is worth noting that there are many 

 advantages in Prof Hough's method of expressing latitudes 

 in direct measures of angular distance. A very suggestive ob- 

 servation was made on February 13. 1S95. The third satellite 

 was then observed in transit, at first as a black spot, but after- 

 wards as a white disc; "after emersion, when the distance 

 from the limb of the planet was o"'4, the outline was sharply 

 defined, and there was an absence of glow around the disc as 

 though the satellite was inmiersed in a medium which absorbetl 

 some of its light." 



Comet Perrine-Lamp (1896 L), which attracted consider- 

 able attention in the early part of the year, has probably now 

 passed out of reach of even the largest telescopes. M. Schulhof 

 has computed hyperbolic elements for this comet ; but while 

 the hyperbolic character of the orbit is still uncertain, it is 

 established that the comet is not one of short period. 



THE RE LA TIVE LENG THS OF POS T- GLA CIAL 



TIME IN THE TWO HEMISPHERES. 

 COME interesting observations on underground temperature 

 ■— ^ have recently been made at Cremorne, near Port Jackson, 

 in New South Wales.' The bore is 2939 feet deep, the mean 

 temperature at the surface is 63" F., and the temperature at the 

 depth of 2733 feet was found to be 97° F. The observations 

 having been made with great care, the resulting gradient of 1° F. 

 per So feet would appear to be "a good approximation to the 

 truth." The rocks of the district down to a depth of about 

 3000 feet consist of sandstones, shales and conglomerates, and 

 therefore, so far as conductivity is concerned, seem to be not 

 unlike the rocks penetrated by the shafts of coal-mines in the 

 north of England, or those in which Forbes' rock-thermometers 

 were sunk in the neighbourhood of Edinburgh. 



The estimates of the relative lengths of post-Glacial time in 

 the two hemispheres, given on p. 138, are based on the following 

 assumptions, the first three of which, it is needless to say, are 

 only rough appro.ximations to the truth. It is supposed (l) that 

 in each hemisphere the gradient beneath the ice-sheet at the 

 close of the Glacial period was the same- ; (2) that the gradient 

 at the surface may now be taken as equal to the average gradient 

 over the whole boring ; (3) that when the ice-sheet disappeared,, 

 the mean temperature of the district rose suddenly to its present 

 value ; and (4) that, previously to its disappearance, the tem- 

 perature of the ground at the base of the ice-sheet was that ol 

 the freezing-point of water due to the pressure of the ice above, 

 say 30°-5 F.^ 



The change in the gradient near the surface after a lapse of / 

 years, due to a rise of b degrees in mean surface temperature, is 

 bj ^(nKt), where k is the conductivity of rock expressed in terms 

 of its own capacity for heat.'' Now, the mean temperature over 

 England averages 49°'5 F., so that b is here 19°, and the tem- 

 perature gradient in the north of England is 1° per 49 feet.'^ 

 Hence, 





1 Report of B. A. Underground Temperature Committee, 1895. 



- This implies that the Glacial period was of the same — or, if not, of 

 very great — length in each hemisphere. 



^ See a paper " On the Effect of the Glacial Period in changing the 

 Underground Temperature Gradient "((jVa/. Mag., vol. ii., 1895, pp. 356-360J. 



•* Rev. O. Fisher, Phii. Mag., vol. xxxiv., 1892, p. 339. 



5 Sir J. Prestwich, " Controverted Questions of Geology," p. 203. 



