September io, 1891] 



NATURE 



453 



intendent. The total number of species included in the Cata- 

 logue amounts to 590, of which 276 are found within the Indian 

 Empire, and 314 are exotic. 



The Smithsonian Institution has issued a set of useful direc- 

 tions, by Leonhard Stejneger, for the use of colle:tors, who, 

 without being herpetological experts, desire to procure for the 

 U.S. National Museum specimens of the reptiles and batra- 

 chians which they may be able to gather in the neighbourhood 

 of their residence or while travelling. The same Institution 

 publishes directions for collecting recent and fossil plants, by 

 F. H. Knowlton ; and notes on the preparation ot rough skele- 

 tons, by F. A, Lucas, 



Students will be glad to welcome the fourth edition of Prof. 

 Milnes Marshall's well-known work on " The Frog : an Intro- 

 duction to Anatomy, Histology, and Embryology." The 

 author explains that the chapter on embryology has been in 

 great part rewritten, and that some new figures have been added. 

 The entire book has been carefully revised. 



The additions to the Zoological Society's Gardens during the 

 past week include a Dorsal Hyrax {Hyrax dorsalis) from Sierra 

 Leone, presented by Mr. Reginald Brett ; a Common Polecat 

 {Mttstela ptttorius), British, presented by Mr. F. D. Lea Smith ; 

 a Ring-necked Parrakeet (Palaornis torquatus) from India, pre- 

 sented by Mrs. Bowen ; an Australian Thicknee {(Edicnemus 

 grallariiis) from Australia, ^presented by Sir Ferdinand von 

 Mueller, C.M.Z.S. ; a Manx Shearwater {Puffinus anglorwn), 

 British, presented by Master Riviere. 



OUR ASTRONOMICAL COLUMN. 



Solar Observations. — In Comptes rendus for August 24. 

 Prof. Tacchini gives a resume of the solar observations made at 

 the Observatory of the Roman College during the second 

 quarter of this year. Spots and faculae have been observed 

 on 73 days, viz. 25 in April, 23 in May, and 25 in June, 

 The following are the results obtained : — 



It is worthy of remark that there was a secondary maximum 

 in May in the case of spots, whilst a secondary minimum is 

 indicated by the observations of prominences. 



Connection between Terrestrial Magnetism and 

 Radiant Sunlight.— Prof. Frank H. Bigelow contributes a 

 note to the American Journal of Science for September, on the 

 causes of the variations of the magnetic needle. He finds, 

 from a discussion of magnetic observations made at thirteen 

 stations during the month of June 1883, that " the permanent 

 magnetic condition of the earth may he principally due to the 

 orbital motion of the earth through the radiant field of sunlight. 

 The rotation of the earth on ils axis causes a modification of the 

 direction of the axis of polarization, by diminishing the angle 

 between the two axes, and as the result of the annual motion 

 may cause it to rotate in a secular period about the axis of figure, 

 or if the magnetization has already become set in the body of the 

 earth, may cause a succession of secular waves to sweep over it 

 fi om east to west, as is shown to be the case in the history of 

 the isogonic lines and the long-period deflections of the needle." 



NO. I 141, VOL. 44] 



This interesting identification of the magnetic and light action of 

 solar radiations is in harmony with the results of the investiga- 

 tions of Maxwell and Hertz. And Prof. Bigelow believes that, 

 by the application of similar considerations to Mercury, he will 

 be able to satisfactorily account for the outstanding motion of 

 this planet's perihelion. 



Two New Asteroids. — On August 28, Charlois discovered 

 the 313th minor planet ; and Palisa found the 314th two days 

 later. 



PHYSICS AT THE BRITISH ASSOCIATION. 



T^HIS Section, as is unfortunately the custom, was housed in 

 -^ an ecclesiastical edifice in which no provision had been 

 made for the exhibition of apparatus or lantern slides by the 

 readers of papers. No doubt, it is impossible always to provide 

 accommodation equal to that furnished two years ago at New- 

 castle, when the Physical Lecture Theatre of the Durham 

 College of Science, with its appliances, was placed at the dis- 

 posal of the Section. Still, it should be possible to provide 

 lantern and screen, and provision should be made, when 

 necessary, for partially darkening the room. If there were a 

 guarantee that lantern slides could always be exhibited, many 

 readers of papers would avail themselves of the opportunity to 

 illustrate their communications much more adequately than is 

 possible at present, when the only appliances are a piece of chalk 

 and a diminutive blackboard ; e.g. on Monday morning the 

 beautiful photographs of Mr. Clayden and Dr. Copeland had to 

 be passed round from hand to hand instead of being exhibited in 

 a manner which would have done justice to their merits. The 

 contents of many of the papers, too, would be much more easily 

 and pleasantly grasped if such a course were adopted. 



Unfortunately, some of the leading physicists, notably Sir 

 William Thomson, Lord Rayleigh, and Prof. Fitzgerald, were 

 unable to be present. Prof. Lodge, however, admirably filled 

 the chair, and spared no exertion in the endeavour to clear up 

 points of obscurity or difficulty that arose during the discussion. 



In all, some fifty papers and reports were read. In the 

 limited space at our disposal, we regret that it is only possible to 

 refer to communications of general rather than of special scientific 

 interest. 



After the President's address on Thursday m irning, Prof. 

 Newton communicated a most interesting account of the action 

 of Jupiter on small bodies passing near the planet, in which he 

 showed that if a comet pass in front of Jupiter, owing to the 

 gravitational attraction between the two bodies the kinetic 

 energy of Jupiter will be increased, while that of the comet 

 will be diminished, and may be diminished to such an 

 extent as to cause it to form (though possibly only tem- 

 porarily) a member of the solar system. On the other hand, 

 if a comet, already a member of the solar system, pass behind 

 Jupiter, the kinetic energy of the planet will be diminished 

 and that of the comet will be increased, and may con- 

 ceivably be increased under favourable circumstances to such 

 an extent that the comet may no longer remain as a member of 

 the system. Prof. Newton had calculated that of 1,000,000,000 

 comets from space crossing, in all directions, a sphere equal in 

 diameter to that of Jupiter's orbit, about 1,200 would come near 

 enough to Jupiter to have their period so much diminished as to 

 be less than that of the planet. 



Mr. W. E. Wilson read a paper on the absorption of heat 

 in the solar atmosphere, and exhibited some of the apparatus 

 he had used in the investigation. The method of observation 

 employed consisted in allowing the sun's image to transit 

 across the thermo-electric junction of a Boys radio- micrometer. 

 He finds that the solar radiation from the extreme peri- 

 pheral portion of the disk is distinctly less than that from 

 the central portions. In this respect the sun's radiation differs 

 entirely from that of the moon, in which there is little or no 

 such difference in the illumination of different parts of the sur- 

 face. This difference is attributable to the absorption of heat in 

 the solar atmosphere, which will necessarily be much more 

 marked for the peripheral than for the central portions of the 

 disk. 



Mr. G. H. Bryan presented an elaborate report on researches 

 relative to the second law of thermodynamics, in which is 

 described an exceedingly simple mechanical representation of 

 Carnot's reversible cycle. 



