January i 2, 1899] 



NA TURE 



;d7 



the area under the rule of the British South Africa Company, 

 north and south of the Zambesi. Among the articles in the 

 present number is a very interesting one on some South African 

 beetles, by the Rev. J. O'Neil, S.J., illustrated by photographs 

 of the chief species described. The magazine can be obtained 

 from the Rev. A. M. Daignault, 114 Mount Street, London, W. 



The annual report (new series, vol. ix.) of the Geological 

 Survej' of Canada, referring to the operations of the Survey in 

 1S96, has been received. The volume comprises 816 pages. It 

 is .accompanied by five maps and illustrated by twenty plates, 

 besides a number of figures in the text. The several parts com- 

 posing the volume have been issued separately, and most of 

 them have been referred to in these columns. Dr. George M. 

 Dawson's summary report, occupying 144 pages, shows that 

 the Canadian Survey accomplished work of great economic im- 

 portance in 1S96, and added to scientific knowledge by original 

 observations and deductions, and by exploration of new ground 

 in the field. 



A SERIES of monthly star maps has been prepared by Air. 

 Walter B. Blaikie, and issued by the Scottish Provident 

 Institution in a blotting-book. There are two maps for each 

 month, one showing the aspect of the sky in the latitude of 

 London, at 10 p.m., when looking north, and the other the 

 southern aspect. The stars are printed in gold on a blue ground, 

 and the positions of the chief planets visible are indicated. In 

 addition to the maps, which will enable beginners easily to 

 find their way among the constellations, a number of notes on 

 interesting astronomical objects are given by Mr. Blaikie. The 

 idea of issuing maps of this kind from an assurance office is an 

 excellent one, and it has been well carried out. 



We have received the Sitzunosbtrichie der Kaiserlicheii 

 Akadcmie der Wissenschaflen, Vienna, containing papers pre- 

 sented to the section of mathematics and natural sciences during 

 the period from January 1S97 to March 1S98. The report is 

 divided into four parts, referring to different branches of science, 

 and each part is published in several divisions. The first part 

 contains papers on natural sciences ; the second comprises 

 (a) papers on mathematics, astronomy, physics, meteorology, 

 and mechanics, and (/') papers on chemistry ; and the third 

 part contains papers on anatomical and physiological sub- 

 jects, excluding purely medical matters. Many of the - papers 

 have already been referred to in these columns, and with the 

 others now before us they make a valuable addition to scientific 

 knowledge. 



The question as to the best means of isolating a freezing 

 mixture is one of consider.able practical importance in chemical 

 and physical work. In the current number of the Berichle, 

 Prof. W. Ilempel describes a series of eomparative experiments 

 undertaken by him to settle which substance was most suitable 

 for ordinary work. Starting with a temperature of about - 75' 

 to - 80° C. , produced by solid carbon dioxide and ether, the 

 rate of rise of temperature with time was rheasured, and, as a 

 result, eiderdown was found to be the best insulator, wool care- 

 fully dried at 100° C. being nearly as good, and having the 

 advantage of cheapness. Three samples of vacuum tubes, of 

 the pattern invented by Prof. Dewar, were also tried, and were 

 found to give very varying results amongst themselves, and all 

 being much inferior in insulating power to either eiderdown or 

 cotton wool. Thus with eiderdown a rise of 12° C. occurred in 

 eighty-eight minutes, with dry wool a rise of 20' to 24° C. in the 

 same time, whilst the three vacuum-jacketed tubes gave under 

 the same conditions rises of 65", 69°, and 39° respectively. The 

 results would seem to show that trustworthy Dewar tubes cannot 

 be bought commercially. 



NO. 1524, VOL. 59] 



The additions to the Zoological Society's Gardens during the 

 past week include a Huanaco [Lama hiianacos, i ) from Punta 

 .■\renas, presented by Mr. Henry F. Fox ; a Crossbill (Loxia 

 cun'iros/ris), European, presented by Mr. H. O. Blanford : 

 two Delalande's Geckos { Tarentola delalandi] from West Africa, 

 presented respectively by Mr. Percy Leach and Mr. H. Munt ; 

 three Grey Squirrels {Schirus cinereus) from North America, 

 two Dorsal Squirrels (Sciunts hypopyrrhus) from Central 

 America, three Nose-crested Iguanas (Iguana iubtrctilata rhin- 



ohphiis] from Nicaragua, a • Iguana {Iguana, sp. inc. ) from 



Tropical America, deposited ; a Leopard, Black variety (Felis 

 pardits), from Africa, three Brazilian Caracaras {Polyhoriis bra- 

 s/lieiisis) from South America, two Warty-faced Honey-eaters 

 (Xanthony~.a phyrgia) from Australia, purchased. 



OUR ASTRONOMICAL COLUMN. 



Comet Chase. — This comet, which is a faint object and 

 difficult to observe, has the following ephemeris for the present 

 week : — 



Ephemeris for Berlin Midnight. 

 1S99. R.A. (app.). Dec. (.ipp.). 



Jan. 13 

 15 



19 



II 8 48 

 9 15 

 9 35 

 9 48 



II 9 55 



+ 30 54 '6 

 31 179 



31 4i'2 



32 4-6 

 + 32 27 7 



Its brightness is now about the same as that at the time of 

 its discovery, and is on the decrease. 



Artifici.-m, Moon Markings. — Mr. S. H. R. Salmon has 

 sent to us a series of slides which are of great interest, since 

 they appear to represent portions of lunar landscapes, and are 

 astonishingly like the real photographs of them. In fact, among 

 all artificial methods of trying to produce lunar eft'ects with- 

 out the intervention of any hand work this is, as far as we 

 know, the most successful. The process Mr. Salmon employs 

 is very simple and can be easily repeated by any one. It is 

 only necessary to smear a little paste on to a glass slide, and 

 gently warm it from below with a spirit-lamp until it is dry. 

 Observing it then with a microscope, we are confronted with 

 this lunar-like appearance. The slides which we have before 

 us represent many variations of lunar formations. In this one 

 we see a small craterlet on the wall of a large crater, while in 

 another we have rills widening now and again into craterlets. In 

 a third slide we have a large crater, very like some on the 

 moon, showing beautifully the gradation of tone on the sur- 

 rounding wall. All the markings are, as Mr. Salmon states, 

 perfectly accidental, and can be seen with the microscope. The 

 .slides before us are the result of a first attempt at micro-photo- 

 graphy on the part of Mr. Salmon, and he is to be congratulated 

 on obtaining such excellent results. 



A New Dome for Equatorials. — The natural evolution 

 in the construction of domes under which equatorials are housed 

 is the elimination of the shutter. Shutters, if they are not per- 

 fect, are the causes of so many evils in an observatory, for they 

 may leak, jam, break, and in several other ways do indirectly 

 damage to a valuable instrument. There are several ways in 

 which a dome can be erected and found to work satisfactorily 

 without their presence, and one, set up at Greenwich in 1S91 for 

 a transit instrument, has met with marked success. In this 

 case the dome consists of two halves, and as the aperture is 

 required only in the meridian, these are made to roll back one 

 east and the other west. More recently the idea has been ex- 

 tended to the new altazimuth, also at Greenwich ; but here the 

 halves are mounted on a ring girder, to allow the aperture to 

 take up any required azimuth. In both these cases the openings 

 had parallel sides. 



A later modification for equatorials, due to Messrs. T. Cooke 

 and Sons, of York, is described and illustrated in the current 

 number of the Observatory (January), and here the opening is 

 wedge-shaped. The arrangement, as described by the makers, 

 is the following. 



" Our object was to do away with the usual shutter covering 

 an opening in the dome. To carry this into effect, the dome is 



