July 7, 1923] 



NA TURE 



19 



difficulties that are encountered in a preliminary 

 reconnaissance for precise triangulation. The first 

 part of the publication discusses the character and 

 strength of triangulation figures, selection of sites, 

 and intervisibility of stations. The second part 

 deals with signal building, and includes practical 

 directions, with detailed plans and specifications. 

 The section on hydrographic signals is specially 

 interesting. Signals of some kind or other, either 

 ashore or afloat, are frequently necessary in the 

 location of soundings off a low fiat coast. Full 

 plans and illustrations and a note of the amount 

 of material required are given. 



The third number of volume i. of the Japanese 

 Journal of Botany has just been issued by the National 

 Research Council of Japan. In addition to botanical 

 papers, it contains reviews of the current Japanese 

 botanical literature, much of which is published only 

 in Japanese and has hitherto been unavailable to 

 workers in other countries. This is therefore a 

 \ aluable feature of the Journal, and should be of much 



service in making more widely known the work of 

 Japanese botanists. The present number contains 

 papers in English and German, chiefly on genetical 

 subjects, as well as abstracts of the principal botanical 

 papers which have appeared in Japan during the 

 period April-September 1922. 



M. Marcellin Boule, the eminent French anthropo- 

 logist, in the Huxley Memorial Lecture for 1922, 

 published in the Journal of the Royal Anthropological 

 Institute (vol. lii., 1922), describes the services 

 rendered to the study of man by the late Prince 

 Albert I. of Monaco. The Prince, impressed by the 

 importance of the remarkable cave records in southern 

 France, devoted much attention to the develop- 

 ment of these discoveries, of which M. M. Boule gives 

 an interesting account. One important result of his 

 work was the establishment of the Institute at 

 Monaco, where the treasures recovered from the caves 

 find a suitable home, and where the study of them 

 can be conducted. 



Our Astronomical Column. 



D'Arrest's Comet. — This interesting periodic 

 comet is due at perihelion in two months, and its 

 detection in July may be hoped for, as it is well 

 placed in the evening sky. Mr. F. R. Cripps has 

 calculated the perturbations by Jupiter and gives the 

 following elements and ephemeris (for midnight) in 

 B.A.A. Journal for May : — 



T=i923 Sept. 14-12 G.M.T. 



w=i74° 7' 15"! e =o'6i6a 



= 143 32 18 ,-1925-0 log a =0-5478 



i= 18 3 47 j log q =0-1311 



R. A, N. Decl. log r log A 



July 8. i6h 26-0"^ 12° 19' 0-193 9'856 



,, 12. 16 25-2 II 6 



,, 16. 16 25-2 9 42 o-i8i 9*847 



,, 20. 16 26-1 8 8 



,, 24. 16 28-1 6 24 0-170 9-841 



The comet is nearest to the earth at the end of July 

 and brightest in mid-August. The moon will cause 

 difficulty in the latter part of July. The positions 

 given above lie in the southern part of Hercules, and 

 are nearly due south at the end of twilight. 



There is no further confirmation of the announce- 

 ment of the discovery of a comet by Abbot at Athens. 



The Coming of the Perseids.- — Mr. W. F. Denning 

 writes : " Early meteors from the great August shower 

 are occasionally visible at the beginning of July. 

 They should be carefully observed, as it is desirable 

 to ascertain the opening date of the display. A few 

 meteors, if observed at two stations, might satis- 

 factorily settle the question, though, at its first on- 

 coming, the shower is but slightly manifested. This 

 year there will be no moonlight to interfere with 

 the maximum on about August 11 or 12, and with 

 clear weather the event should be witnessed under 

 good conditions. There is no reason for expecting 

 that the ensuing return will be one of very rich 

 character, but the Perseids form an annual spectacle 

 of meteoric activity not equalled by any other 

 system. A maximum of special intensity was 

 witnessed on the morning of August 12, 1921, when 

 the hourly number of meteors visible to an observer 

 was 250. There is evidence to show that the shower 



presents itself most richly at intervals of 11-75 years, 

 but more observations are required. Its duration 

 continues over the two summer months of July and 

 August. 



" The Perseid shower will be supplemented by 

 other radiants, the following being among the more 

 prominent ones visible at or from about the middle 

 of July and, in certain cases, for some time after- 

 wards : — 



16° +31° 47° +44° 303° -10° 334° +73° 



22 +21 270 +47 303 +24 335 +58 



25 -f43 292 +53 312 +62 339 -12 



42 +22 281 +44 315 +48 343 +12 



There are certainly more than 100 different systems 

 in play, but the great majority of them are feeble and 

 apparently the relics of nearly exhausted streams 

 which possibl)^ formed rich displays in ancient times." 



Perturbations of the Minor Planets. — Prof. 

 A. O. Leuschner has published a useful report on 

 this subject as a Bulletin of the Research Council 

 of the National Academy of Sciences, Washington. 

 It deals with twenty-three interesting planets, includ- 

 ing the four bright ones, Eros, Andromache, and the 

 six Trojan planets. Tables are given of all orbits 

 published, with a statement of the method by which 

 they were derived. 



It is obvious that the vast host of minor planets 

 can only be observed efficiently if there is a methodical 

 division of labour. Arrangements for this had been 

 made before the War, which threw them into con- 

 fusion, and it is welcome news that Prof. Leuschner's 

 Bureau is again making arrangements for this 

 purpose. At present planets that are better known 

 are frequently observed to an unnecessary extent, 

 while others are neglected. Marseilles Observatory 

 has published numerous orbits and ephemerides of 

 late years, but it has not been in touch with all the 

 countries where observations were being made. 

 One point emphasised in the report is the importance 

 of giving clear information in all published orbits 

 of the materials that were used in obtaining them, 

 and the perturbations that were applied. Several 

 cases are quoted in which this information is lacking. 



NO. 



2801, VOL. I 12] 



