52 



NATURE 



[July 14, 1910 



The issue of the " Statesman's Year-book " for 1910 has 

 been published by Messrs. Macmillan and Co., Ltd. This 

 is the forty-seventh annual publication of an invaluable 

 work of reference. The information throughout the 1500 

 pages has been corrected to the latest available date, and 

 the changes made necessary by the death of King 

 Edward VIL and the accession of King George V., as 

 well as those arising out of the Union of South Africa, 

 have been recorded. The proposed changes in the adminis- 

 tration of the Belgian Congo are indicated ; the sections 

 on China and on the .^nglo-Egyptian Sudan have been 

 improved. Among matters of current interest, reference 

 may be made to the articles on " Second Chambers " and 

 the results of the census of production. hs usual, the 

 annual provides a number of new maps, and among them 

 may be mentioned those showing the development of the 

 Congo, the proposed Central Scotland and Georgian Bay 

 Ship Canals, the United South Africa and South African 

 railways, and South America, showing the railways. 

 .Altogether,- this edition of the " Year-book " is well up to 

 tine high standard one associates with Dr. Scott Keltic's 

 editorship. The price of the book is 105. 6d. net. 



Messrs. Reem.4N, Ltd., hope to publish during the pre- 

 sent month a new book by Dr. Bernard Hollander entitled 

 " The Mental Symptoms of Brain Disease," with a preface 

 by Dr. J. Morel, Belgian State Commissioner in Lunacy. 



K second edition of Dr. Washington's " Manual of the 

 Chemical Analysis of Rocks " has been published by 

 Messrs. John Wiley and Sons in New Y'ork and Messrs. 

 Chapman and Hall, Ltd., in this country. The first 

 edition appeared in 1904, and was reviewed in these 

 columns on January 5, 1905 (vol. Ixxi., p. 219). The pre- 

 sent issue has been revised and somewhat enlarged. 



OUR ASTRONOMICAL COLUMN. 



H.illey's Comet. — Dr. Ebell's ephemeris for Halley's 

 comet is continued in No. 4423 of the Astronotnische 

 NacJxricbten, and gives the positions, &c., up to Sep- 

 tember 18. On July 16 the comet will be in R.A. 

 loh. 59-4m., dec — 4° 2'7', and its estimated magnitude 

 will be 6'3, so that further observations in these latitudes 

 are impossible. The distances from the earth and sun, on 

 that date, will be 197 and 162 million miles respectively. 



Owing to its apparent proximity to the sun, the comet 

 could not be extensively photographed at any one observa- 

 tory, but it is hoped that when the results from various 

 observatories come to be compared, there will be a fairh' 

 continuous record which will enable the changes in the 

 tail to be closely followed. An example of such change is 

 afforded by the negatives secured at Johannesburg on 

 April 21 and Kodaikanal on April 22, the latter showing, 

 among other changes, a large contorted streamer on one 

 side ; the similarity to the tail of Morehouse's comet is 

 thus emphasised. 



A spectrum of the comet, taken at Mount Wilson, was 

 described by Prof. Fowler, at the last meeting of the 

 Royal Astronomical Society, as being of the usual type. 

 Dark Fraunhoferic lines, due to reflected sunlight, are 

 shown in the narrow strip of the spectrum due to the 

 nucleus, and in that of the coma the bands at \\ 473, 

 421, and 3S8 are seen. Prof. Fowler suggested that the 

 unequal intensities of the five heads in the cyanogen, 388, 

 tiand were, possibly, indications of a rather low pressure 

 condition. A comparison of this spectrum with that of 

 Daniel's comet (1907), taken by Prof. Campbell, shows 

 that they are practically identical. 



In the Comptes rendus (No. i) for July 4 Prof. Eginitis 

 describes the appearance of the comet at .Athens since its 

 inferior conjunction. -An increased activity of the nucleus 

 ejected large masses of matter to great distances, and on 

 May 31 an aigrette was seen, which was brighter than the 

 nucleus itself and turned away from the sun ; this was 

 made up of straight streamers 50" long diverging to form 



an angle of 60°. It was also noticed that, after the 

 passage, the tail became much more brilliant than before, 

 an effect which the author ascribes, in great part, to the 

 change in the relative positions of the comet, the sun, and 

 the observer. From this he deduces that the brilliancy of 

 the tail is largely due to reflected sunlight, and suggests 

 that it affords further evidence that the tail is, to an 

 appreciable extent, made up of fine, solid particles. 



Photographic and visual observations of the spectrum, 

 made at the Madrid Observatory since the conjunction, 

 are described by Father Iniguez. Photographs taken on 

 June I, 3, and 6 show the continuous spectrum and seven 

 superposed monochromatic images of the coma. The three 

 least refrangible of these were Observed in May, and of 

 the four new ones the two brightest are in the extreme 

 ultra-violet, beyond the continuous spectrum. The plate 

 taken on June i shows each of the three less refrangible 

 bands doubled. Three of the four more refrangible bands 

 are well defined, and their wave-lengths are given as 437, 

 425, and 391 ; the other is broad, extending from A 399 

 to \ 407. The visual observations indicate an intrinsic 

 change in the band recorded as X 567 on May 27 and as 

 A 559 on May 30 ; on the former date the red edge was 

 sharp, whereas on the latter it was diffuse, and was not 

 the most intense part of the band. The green band at 

 A 512 on May 27 and A 516 on May 30 was sharp and 

 apparently composite, and the difference of wave-length 

 is attributed to a relative change in the intensities of the 

 components inter se. .Apparently the band at A 472 did 

 not change. The visual and photographic observations 

 of the tail showed various, although not pronounced, 

 changes, which are discussed in the note ; until May 6 

 the tail was of the first type, but from then until the 

 passage of the comet it was of the second, reverting to 

 type i. after the passage. 



Prevention of Dew Deposit upon Lens Slrf.aces. — In 

 a paper published in No. 7, vol. l.\x., of the Monthly 

 -Notices, Mr. Franklin Adams states that the Mervel Hill 

 photography of the northern hemisphere stars could have 

 been completed in two years instead of nearly six if some 

 means had been devised for preventing the deposition of 

 dew on the lens surfaces. 



He then describes a method by which the difficulty has 

 now been overcome. .An air-pump, driven by a motor, 

 delivers a current of dried air on the lens surfaces, inside 

 the camera, and on the film of the plate, thus preventing 

 the dew deposits. The air is dried by forcing it over 

 pumice stone soaked in sulphuric acid and then over glass 

 wool. 



-A Varlable Star as a Time Constant. — Having regu- 

 larly observed a variable star. No. 33 in the Harvard list, 

 in the cluster M. 5 (Libra), Prof. Barnard discusses its 

 light-changes in No. 4409 of the Astronomische Nach- 

 richten. This star was compared with a neighbouring 

 star, which is designated k, and for ten years its period 

 has apparently remained unchanged. Therefore Prof. 

 Barnard suggests that it, and other similar variables, 

 might prove useful for providing a check on the constancy 

 of the earth's rotation, or any other possibly variable 

 elements of the solar system. It rises sharply to a maxi- 

 mum, at which it seems to remain for only a few minutes, 

 and then declines quickly until it is as bright as k ; after 

 that the decline is more leisurely. At minimum the magni- 

 tude is 14-6, and the increase is rather more than i-2 

 magnitudes, the period being 0-50147 -f-d. To facilitate 

 observations of this interesting time-standard. Prof. 

 Barnard gives an ephemeris which is useful up to the 

 year 19 iS. 



Radiation and Absorption. — In discussing various 

 astronomical phenomena, the observer often has to study 

 numerous laws concerning radiation and absorption, and 

 this frequently necessitates looking them up especially. 

 To obviate waste of time in this direction, Prof. Humphreys 

 brings together, in No. 4, vol. xxxi., of the Astrophysical 

 Journal, the chief laws, and discusses the general formulae 

 by which they are expressed. Thus the equations for the 

 Doppler, Maxwell-Bartoli, Zeeman, and other effects are 

 explained, and the most convenient formulae for general 

 use are collected in an invaluable summary which should 

 prove of great convenience. 



NO. 2124, VOL. 84] 



