2 6o 



NATURE 



[October 31, 1912 



flections in the instrument or other causes. The 

 simple method suggested by Mr. Twyman of altering 

 the focussing, when true lines should go out of focus 

 and spurious lines behave irregularly, seems not to 

 have been applied by any of the earlier observers. The 

 favourite method has been to combine two instru- 

 ments giving dispersions at right angles to each other, 

 the two producing a series of interference points. 

 Dr. L. Janicki, of the Reichsanstalt, using two 

 Lummer plates, one of which was slightly wedge- 

 shaped, has recently shown in this way that the 5461 

 line consists of twelve components, the line previously 

 regarded as the principal line consisting really of a 

 group of five. 



The study of the characteristics of the motion of 

 a train during the accelerating period has assumed an 

 importance indicated by the fact that the actual choice 

 of a method of traction for services of a suburban 

 character depends upon the suitability of the tractor to 

 work the train during the accelerating period. Prof. 

 VV. E. Dalbv, in a paper read at the Institution of 

 Mechanical Engineers on October 25, describes a 

 useful method by means of which time-speed, time- 

 distance, speed-distance, and energy-distance curves 

 may be derived from a curve of tractive force ex- 

 pressed as a function of the velocity. A method of 

 reducing the data obtained from a dynamometer-car 

 record is also considered, together with the illustra- 

 tion, bv means of a dynamical diagram, of the prin- 

 ciples underlying the practice of braking. The accu- 

 racv of the curves deduced can be easily checked. 

 The whole family may be drawn rapidly by means of 

 the integraph, starting with a curve of tractive-force. 



A SECOND edition of "The A. B.C. Guide to Astro- 

 nomy," by Mrs. H. Periam Hawkins, has been pub- 

 lished by Messrs. Simpkin, Marshall, Hamilton, Kent 

 and Co., Ltd. Tlie book has been brought up to date, 

 and a photograph of the zodiacal light, taken by Prof. 

 Douglass, at Flagstaff Observatory, Arizona, U.S.A., 

 has been included as a frontispiece. The price of the 

 little volume is is. bi. net. 



A CHEAP edition of Captain Mayne Reid's "The 

 Naturalist in Siluria," has been published by the 

 Year Book Press. The price of the volume is is. 

 net. From his house in the Woolhope district, the 

 author could look over the whole series of Upper 

 Silurian rocks, from near Hereford in the north to 

 their southern projection by Gorstley, in Gloucester- 

 shire. Manv dwellers in this naturalist's paradise, as 

 Mayne Reid called it, will welcome this reprint of 

 his observations. 



Prof. S. W. Williston's " .'\merican Permian 

 Vertebrates," which was reviewed in Nature of 

 October 24, was published in 191 1. There was no 

 date on the title-page, and therefore we printed the 

 letters "n.d." with the bibliographical particulars at 

 the head of the notice. The manager of the Cam- 

 bridge University Press now points out that at the back 

 of the title-page it is stated that the volume was pub- 

 lished in Chicago in October, 191 1. We cannot 

 attempt, however, to do more than give particulars 

 from the title-pages themselves at the head of notices 

 in our review columns. 



NO. 2244. VOL. 90] 



OUR ASTRONOMICAL COLUMN. 

 Astronomical Occurrences for November : — 

 Nov. 4. i5h. om. Mars in conjunction with the 

 Sun. 

 5. 2ih. om. Pallas in conjunction with the 

 Moon (Pallas 0° 26' N.). 



7. I5h. 59m. Venus in conjunction with 



Jupiter (Venus 1° 43' S.). 



8. i3h. 28m. Mars in conjunction with the 



Moon (Mars 3° 7' N.). 



10. 6h. 50m. Mercury in conjunction with the 



Moon (Mercury 1° 54' N.). 



11. ih. 2im. Jupiter in conjunction with the 



Moon (Jupiter 5° 5' N.). 

 ,, 8h. 2im. Venus in conjunction with the 



Moon (Venus 3° 21' N.). 

 13 to 15. Ma.ximum of Leonid Meteor Shower. 

 14. 7h. S9m. LIranus in conjunction with the 



Moon (Uranus 4° 27' N.). 



19. ih. om. Mercury at greatest elongation 



east of the Sun (22° 14'). 



20. i6h. 54m. Mercury in conjunction with 



Jupiter (Mercury 2° 47' S.). 

 22. i8h. om. Saturn at opposition to the Sun. 

 24. ^h. 47m. Saturn in conjunction with the 



Moon (Saturn 6° 17' S.). 

 27. 2oh. 49m. Neptune in conjunction with the 



Moon (Neptune 5° 33' .S.). 



Schaumasse's Comet 19126. — The identity of the 

 comet discovered by M. Schaumasse on October 19 

 with Tuttle's comet, last seen in 1899, 's shown by 

 the elements for its orbit, published in Circular 

 No. 136, from the Kiel Centralstelle, and given below 

 in the first column : — 



ivi?/' I utile 5 



(Fayet and schaumasse) (Rahts) 



IT =113° 50' 2o""j =116° 29' 3"1 



fl=27o 23 58 j-igia-o =269 49 54 I19000 



'■ = 53 52 34 J = 54 29 16 J 



(/ = I 0506 =roigr 



According to the new elements, perihelion passage 

 took place on October 25^3 153 (Paris M.T.), when the 

 comet was some 97'6 million miles from the sun. The 

 previously calculated time of perihelion was January 3, 

 1913, and thus, as a writer in The Times (October 

 24) points out, the present revolution is the shortest 

 on record, as was also the case with the last return 

 of Halley's comet. The difference of seventy days 

 between the calculated and actual returns will probably 

 be disclosed when the planetary perturbations during 

 the last cycle are taken into account. 



The ephemeris given in the Centralstelle circular 

 indicates that the comet will not become brighter, 

 is travelling southwards rapidly, and will not be 

 visible in the northern hemisphere after November 



23- 



Ephemeris \2h. (M.T. Paris). 



10 54'5 



1 1 67 



28 37 



Gale's Comet 1912a. — A number of observations 

 of comet 1912a are published in No. 4606 of the 

 Astronomische Nachrichten, and a photograph by Mr. 

 H. E. Wood at Johannesburg is reproduced. On 

 September 13 the comet was visible to the naked eye, 

 magnitude 5, and had an almost stellar nucleus sur- 

 rounded bv an even coma 4' in diameter. The tail 

 was fan-shaped, with an angle of about 60°, the 

 branch to the south being 40' long, while the south- 

 following branch had a length of !°. On a photo- 

 graph taken with the Franklin-Adams camera, expo- 

 sure 40m., the former branch is the same length, but 



