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NA TURE 



[February 26, 1903 



distances up the river valleys. ... As we enter the timbered 

 country on the higher foot-hills and lower mountain sides, 

 we encounter a fauna which, while not unmixed with species 

 that have come up from the plains, shows a strong affinity 

 to the life about our Great Lakes. Higher still — from about 

 8000 to 9000 feet — we meet with species of genera still more 

 boreal in their habits. . . . Above timber line the peaks 

 sustain a few beetles which seem to be of Arctic origin, left 

 probably by the retreating ice-sheets of the Glacial period." 



In the January issue of the Journal of Anatomy and 

 Physiology, Dr. Tims discusses the evolution of the cheek- 

 teeth of mammals. In the development of the premolar 

 series it is considered that the increase or suppression of the 

 cusps of the cingulum has played a part. The molars appear 

 to have attained complexity by the fusion of two or more 

 simple teeth in the same line. The molars of a rabbit re- 

 present a simple type, in which two cones, with their cingu- 

 lum, have been fused. In most rodents two cones seem 

 to be involved, although in the water-vole four may be 

 united. The two outer cusps on the upper molar of a dog 

 represent two elements united by fusion, and the evolution 

 of the molars of ruminants is believed to run on parallel 

 lines. The author adopts the concrescence theory of dental 

 evolution, so far as it relates to fusion in the molars of 

 cones situated in the same line ; but is unable to find evidence 

 of fusion out of this line, and cannot accept the view that 

 cones of two dentitions are represented in the molars. 



The London Stereoscopic Company has sent us a list of 

 cameras, lenses, optical lanterns and other apparatus con- 

 nected with photography which are offered for sale at greatly 

 reduced prices in order to make room for new articles. 

 Opportunity is thus afforded for obtaining or supplementing 

 a photographic outfit at much less than the usual cost. 



The February number of the Parents' Review', the monthly 

 organ of the Parents' National Educational Union, contains 

 two articles treating of two distinct branches of nature- 

 study. The first, on " The Boughs of the Branstock," by 

 Mr. W. G. Collingwood, deals with the pictorial representa- 

 tion of trees in an artistic manner; the second, "A Plain 

 Account of a Kerry Potato-patch," by Miss E. A. Magill, 

 describes certain experiments designed to test what could be 

 done by one individual with the least possible capital in the 

 cultivation of a kitchen garden. 



In pursuing his researches on the emanations from radio- 

 active bodies, M. Henri Becquerel has recognised that the 

 rays given off by polonium are identical with the Kanal- 

 strahlen of Goldstein. In the current number of the Comptes 

 rendus, M. Becquerel classifies the various rays as follows : — 

 Uranium emits only one kind of radiation, charged with 

 negative electricity and possessing high penetrating power. 

 The emanation from polonium is charged with positive 

 electricity, and is very easily absorbed, whilst the emanation 

 from thorium and radium contains both kinds of rays. 



The' additions to the Zoological Society's Gardens during 

 the past week include an Agile Wallaby (Macropus agilis), 

 a Brush Turkey (Talegalla latliami), a Frilled Lizard 

 (Chla.mydosa.urus kingi) from Australia, presented by Mr. 

 H. W. Fawdon ; a Two-spotted Paradoxure (Nandinia bino- 

 tata) from West Africa, presented by Mr. C. W. Wilson ; 

 two Red-sided Tits (Pants varius), European, presented by 

 Mr. Howard Williams; a Chimpanzee (Anthropopithecus 

 troglodytes) from West Africa, three Coquerel's Mouse 

 Lemurs (Chirogaleus coquereli) from Madagascar, three 

 Hoarded Lizards (Amphibohtrus barbatus), a Blue-tongued 

 Lizard (Tiliqua scincoides) from Australia, two Black-headed 

 Buntings (Embcriza melanocephala), European, deposited. 

 NO. 1739, VOL. 67] 



OUR ASTRONOMICAL COLUMN. 

 Photographs of the North Polar Region. — In the 

 February number of the Bulletin de la Sociiti astronomique de 

 Frame, M. Flammarion gives an interesting description, em- 

 bodying a catalogue of positions and several charls, of a series 

 of photographs ot the region surrounding the North Celestial 

 Pole. The article describes the obtaining of the photographs 

 and also shows how they indicate very clearly the movement of 

 the pole among the surrounding stars during short intervals of 

 time. In the catalogue, 356 stars, all within 2° of the dole, 

 are arranged in the order of their North Polar distances on 

 September 3, 1902, and their magnitudes, coordinates and 

 numbers in the Redhill (Carrington's 1S57) catalogue of cir- 

 cumpolar stars are also given. The charts show the movement 

 of the pole among these stars during the period 1600 to 2200 

 A. D. , and that Polaris, which is at present No. 129 in the 

 catalogue, will attain its minimum N.P.D. in the year 2104. 



A Device for Obtaining Good Seeing. — In a paper com- 

 municated to the American Journal of Science for February, 

 Prof. S. P. Langley describes a novel device which he has 

 found efficient in producing steady images of the sun and 

 stars when observed with the reflector of the Smithsonian 

 Astrophysical Observatory, and he believes that it will have 

 the same effect when used with refractors. 



Generally the point aimed at in previous attempts to 

 obtain " good seeing " has been to abolish all air currents 

 in and about the telescope tube, but Prof. Langley has found 

 by experiment that the definition is very little improved when 

 this course is followed. After various experiments at 

 different altitudes he arrived at the conclusion that it is the 

 air within a few hundred yards, or even feet, of the tele- 

 scope that has the greatest disturbing effect, and he en- 

 deavoured to find some method of tranquillising this. The 

 reflector he was using was fed by a coelostat, and he caused 

 the reflected beam 'to pass through a long three-walled tube 

 which was covered by a canvas tent, so that the contained 

 air was thoroughly well insulated from the variations of 

 temperature and the draughts in the surrounding atmo- 

 sphere. Very little relief was found as a result of this 

 arrangement, so Prof. Langley tried an experiment of a 

 somewhat paradoxical character, which he found to answer 

 very well. He drew a strong current of air through the 

 inner tube and introduced cross currents by several inleis at 

 various points in the length, thereby thoroughly agitating 

 and mixing the enclosed air. Taking some artificial double 

 stars for his objects, he found that doubles which were 

 blurred and inseparable under the former condition were 

 plainly visible and sharply separated when the air was thus 

 agitated. When the sun was observed under the new con- 

 ditions it was found that the " boiling " on the limb, which 

 is normally so annoying to the observer, was very nearly 

 abolished. No quantitative results are yet ready for publica- 

 tion, but Prof. Langley has no doubts as to the general 

 advantages to be obtained from the application of his • 

 method. 



Proper Motion of the Sun Compared with Stellar 

 Velocities. — In a paper communicated to Section A of the 

 American Association for the Advancement of Science, Profs. 

 Frost and Adams, of Yerkes Observatory, give the results 

 they have obtained, using the Bruce spectroscope, of the 

 radial velocities of twenty stars having spectra of the Orion 

 type. The table of radial velocities included in the paper 

 shows that of all the stars considered, those between 3 hours 

 and 7 hours R.A. have a positive motion, i.e. they are re- 

 ceding, whilst those in the opposite region of the heavens, 

 16 hours to 20 hours R.A., have a negative motion, i.e. they 

 are approaching. This difference is chiefly due to the 

 velocity of the proper motion of the sun, and if the amount 

 of this motion be subtracted from the values obtained, the 

 remaining proper motions of the stars are very small, 

 scarcely any of them having such great velocities as that of 

 the sun. 



Discovery of Ancient Astronomical Records. — During 

 Prof. Hilprecht's excavations at Nippur, a library, which it 

 is estimated contains 150,000 tablets, has been discovered. 

 Many of the tablets refer to ancient astronomical records, 

 and it is expected that when these are finally translated, some 

 remarkable facts concerning the state of astronomical know- 

 ledge during the period about 2300 B.C. will be disclosed. 



