December 15, 1921] 



NATURE 



511 



It would not seem desirable to prejudice the design of 

 a prismatic binocular by attempting to suit this small 

 proportion of extreme cases. 



A PAPER on sea casualties and loss of life, read by 

 Sir Westcott S. Abell befwe the North-East Coast 

 Institution of Engineers and Shipbuilders on Novem- 

 ber 4, gives a very interesting analysis for the period 

 of t«\enty-three years immediately preceding the war 

 (1890-19 13). From the results of this analysis, which 

 are displayed both in tabular and graph form, it 

 appears that the chance of loss of life of a passenger 

 bv reason of marine accident is about 002 per cent. 

 Further, if it were possible to attain absolute per- 

 fection in the ship herself, then the reduction in 

 loss of passenger life would amount to 70 per million 

 passengers carried per annum. If, however, the 

 location of casualty and the fact that technical 

 ship and machinery regulations cannot provide against 

 strandlngs and certain miscellaneous risks be 

 considered, it would be possible to reduce loss of life 

 to 30 per million per annum. Taking the whole 

 r\vent}-three-year period, the number of deaths of 

 passengers at sea from disease is nearly four times 

 rhe number arising from marine accidents. The 

 average death-rate from all causes for European sea- 

 men engaged in foreign trade in British vessels is 

 about 40 per thousand, and the occupational risk is 

 about 2-0 per thousand. The risk to underground 



workers in mines- was about 1-7 per thousand in 

 1913, and averaged 1-5 per thousand from 1890-1900. 



Mr. D. E. Pye-S.mith, of Gonville and Caius Col- 

 lege, has become a partner in the firm of Messrs. 

 Bowes and Bowes, booksellers, Cambridge, which 

 will continue to be carried on under the present title. 



The latest catalogue (No. 90) of second-hand books 

 issued by Messrs. Dulau and Co., Ltd., 34 Margaret 

 Street, W.i, gives particulars of upwards of 1600 

 works on botany, fossil plants, and agriculture, many 

 formerly the property' of the late Prof. Ph. van 

 Tieghem, Paris. The list should be useful to 

 librarians and others. We notice that, in addition to 

 the foregoing, Messrs. Dulau are offering for sale 

 many autograph letters of eminent men of science 

 collected by the late Dr. Henry Woodward and Prof. 

 Rupert Jones. 



Messrs. H. K. Lewis and Co., Ltd., 136 Gower 

 Street, W.C.i, have just published a short illustrated 

 account of the establishment and progress of their 

 seven t)--seven years' (1844-1921) work as medical and 

 scientific publishers and booksellers. Though the 

 pamphlet refers particularly to the medical aspects of 

 the business and the technical and scientific sides of 

 the bookselling and libran,- departments are referred 

 to only briefly, for many years books on all kinds of 

 manufactures have come within the scope of the firm's 

 activities. 



Our Astronomical Column. 



Fireballs. — Mr. W. F. Denning writes : — " On 

 Sunday, December 4, a large fireball was observed by 

 Mr. E. H. CoUinson from If>swich at loh. lom. p.m. 

 It was estimated to be several times brighter than 

 Venus, and its path was from 288+67° ^^ 279+51°; 

 it moved swiftlv, and left a silvery streak along its 

 flight. 



"A large and ver)- brilliant meteor was viewed from 

 Eastbourne and other places on Wednesdav, Decem- 

 ber 7, at 9.30 p.m. It illuminated the sky with a 

 strong glare, and many persons mistook it for ball 

 lightning. Exact particulars of the path of this object 

 have not yet come to hand. 



" Observations of the Geminid meteor shower were 

 commenced from Bristol on the morning of Decem- 

 ber 10 at about 3 a.m. In one hour's watch sixteen 

 meteors were recorded, of which eight belonged to the 

 Geminid stream, the radiant point being well defined 

 at 108+ 32^°. Bright meteors were seen at 3.4 and 

 3.56 a.m., but these belonged to other showers." 



Observers' Handbook. 1922 (British Astro- 

 nomical Association).— When it became known that 

 the ^'Companion to the Obserxatoni- " was being dis- 

 continued, the British Astronomical Association de- 

 cided to fill the gap. entrusting the work to the Com- 

 puting Section, of which Mr. L. J. Comrie is director. 

 The Handbook has just been issued at the price ^to 

 non-members) of is. Its aim is not to supersede, 

 but to supplement, the use of the Natttical Almanac, 

 very little space being given to matter contained there. 



The conditions of visibility of the planets in the 

 different months are exhibited graphicallv in a dia- 

 gram. Phenomena of Saturn's satellites' are given, 

 having been computed by Major Levin. 



Other subjects included are periodic comets, variable 

 NO. 2720. VOL. I08I 



stars (the ephemeris of Algol is corrected by recent 

 observations), double stars, of which a series of test 

 objects is given, graduated for apertures from i in. 

 to 10 in., meteors, occultations, etc. 



There are also descriptive notes on objects of special 

 interest in the stellar heavens, and extensive tables of 

 elements and constants. In short, the handbook 

 promises to be of great utility- to obsers'ers of almost 

 every class. 



Perturb.\tions of Saturn's Rings. — Dr. G. R. 

 Goldsbrough (Phil. Trans., A, vol. 222) examines 

 the perturbations of the ring particles produced bv 

 Saturn's satellites. He neglects the oblateness of 

 Saturn and the mutual actions of the ring particles, 

 and then finds boundaries of the zones of instabilitv 

 produced by the separate satellites. The action of 

 Mimas is predominant, owing to its nearness ; he find 

 that it should produce a division from radius 16-9' to 

 17-64" (heliocentric distances from Saturn's centre), the 

 figures agreeing exactly with the edges of the great 

 Cassini division. It should also produce a clearance 

 from radius 20-2" to its own orbit; the actual outer 

 edge of the ring is at 200". Dione should produce a 

 clearance from Saturn's surface to 9-34'; the actual 

 inner -edge of the crepe ring is at 10-83*. Lowell 

 reported a black band between ring B and the crgpe 

 ring, which the author ascribes to the action of Rhea. 

 It is shown that the dissipative action in each case is 

 most effective in the outer portion of the unstable zone. 

 The author thus explains the failure of Titan to dissi- 

 pate the whole of the bright rings, which lie in Titan's 

 zone of clearance (extending from the planet to radius 

 29-94'), hut in the portion where the dissipative action 

 is weakest. The author concludes, however, that this 

 action will eventually dissipate the whole ring. 



