258 



NA TURE 



[JULV 1 1, 1907 



Rontgen ray and high-frequency apparatus, instruments, 

 and accessories. The list provides full particulars as to a 

 variety of induction coils made by the company, inter- 

 rupters, fluorescent screens, portable accumulators, and 

 high-frequency sets. The information given as to light 

 baths, vibration apparatus, the Finsen lamp and light, and 

 the orthodiagraph, should appeal specially to medical men. 

 The list is conveniently arranged and admirably illustrated. 



A NEW edition of " Bradshaw's Through Routes to the 

 Chief Cities of the World " has just been published. 

 This comprehensive handbook of colonial and foreign 

 travel, besides giving descriptive routes of the chief rail- 

 ways, ocean lines, and caravan tracks, supplies an 

 abundance of maps and plans and some useful vocabu- 

 laries. The volume has been edited by Prof. A. H. Keane 

 and Mr. Stanley Read, and its price is 55. net. The 

 route numbered 50, dealing with tours round the world, 

 is of special interest, .showing as it does the increased 

 facilities for travel since Jules Verne wrote " Round the 

 World in Eighty Days." The actual minimum time re- 

 quired for an all-round journey from London, provided 

 no delay occurred in missing train or boat connections, is 

 38 days 10 hours, and Lieut. -Colonel Burnley-Campbell 

 recently completed the circuit of the world in 40 days 

 195 hours, following the route Liverpool, Quebec, Van- 

 couver, Yokohama, Tsaruga, Vladivostok, Harbin, Irkutsk, 

 Moscow, Warsaw, Berlin, Ostend, Dover ; but the usual 

 quick rate of travel is still 53 days. The book may be 

 commended to teachers as an interesting example of applied 

 geography. 



OVR ASTRONOMICAL COLUMN. 



Transits of Saturn's Satellite Titan and Shadow. — 

 In the Publications of the Astronomical Society of the 

 Pacific, vol. xi.x., p. 125, Hermann Struve gives the 

 following central transits of Titan and shadow during 

 ensuing months : — 



Saturn Rises at Greenwich. 



J"iy 



Aug. 

 Sept. 

 Oct. 

 Nov. 

 Dec. 



II 28 p.m. 



9 28 „ 



7 24 ,, 



5 22 „ 



3 16 „ 



I 18 ,, 



Comet iqoyd (Daniel). — A new set of elements and a 

 daily ephemeris for comet 1907^ are published by Dr. 

 Stromgren in No. 4187 (p. 191, June 29) of the Astrono- 

 mische Nachrichten. A part of the ephemeris is given 

 here; and, in order to facilitate the location of the object, 



NO. 1967, VOL. 76J 



the daily positions, with respect to the surrounding si 

 are marked on the accompanying chart ; — 



Ephi 



1907 



6(t, 



{M.T. Be 



-;.■..). 



log A 

 00216 



July 10 ... I 3yo ... + 7 35'i ... 0-1318 



-t- 8 167 



4- 8 58-8 ... 01133 ... 99977 ■•• 



+ 9 41-2 



-no 23-6 ... 0-0942 ... 99756 ... 



4- II 5-9 



4-11 47-8 ... 0-0744 ... 9-9558 

 .\ccording to Dr. Stromgren 's elements, perihelion 

 occur on September 94. 



iPBhi- 



3'50 



425 



5>4 



6-17 

 will 



Appa!. 



■ 907,/, July 



.As will be seen from the above ephemeris, the comet is 

 brightening rapidly, and may yet become a faint naked- 

 eye object. .At present it is an easy object, when found, in 

 a 3-inch refractor. It has a distinct stellar nucleus which, 

 according to Dr. Zappa, of Rome, was centrally placed 

 and of magnitude 8-5 on June ib. A faint fan-shaped tail 

 was seen on June 21. 



Mars : the Duplication of TtiE Soi.is Lacus. — In 

 Bulletin No. 28 of the Lowell Observatory, Prof. Lowell 

 records that the .Solis Lacus showed double on May iS, 

 this being the first lime that it has appeared divided since 

 the summer of 1S94. This is not a case of gemination, for 

 tlie two portions arc not alike either in shape or size, 

 nor were they in 1894. .Among the canals which emerge 

 from the eastern part, a new one was delected for the 

 first time on May iS, and has been designated Ichon 

 The South Polar cap has retreated southward since the 

 last presentation, leaving dark ground behind it, and it is 

 noticeable that the canals connecting with the Sclis Lacus 

 on the south are darker and more easily seen than those 

 proceeding from it towards the north, although the tilt of 

 ihe planet's axis bhr.uld render the former the more difficult 

 to detect. As the snow has left dark ground behind it, 

 darker than is the case in this region in the later part of 

 the Martian year, Mr. Lowell argues that water, and not 

 CO,, is concerned. As a consequence, it follows that the 

 temperature in tliis region — lat. 42''-52° — was already 

 higher than 0° C. on May 18, or, in the Martian year, on 

 a date corresponding to -March 13 of our calendar. 



Variable Stars. — Astrononiischc Nachrieliten, "So. 4180 

 (June 28), contains several important communications con- 

 cerning variable stars. The first is by Messrs. Mijller and 

 Kempf, of the Potsdam Observatory, on the peculiar 

 variable X Persci, which they have now observed regularly 

 for twenty years. The present paper gives the observ- 

 ational record since September, 1899, and is accompanied 

 by a light curve showing the peculiar fluctuations of 

 magnitude which tills star undergoes. 



In the second paper M. Luizet records some maxima and 

 minima of several long-period variables, among the stars 

 dealt with being o Cc-ti, R Leonis, and S Corona;. 



The third communication is from the Harvard College 



