May 25, 1911] 



NATURE 



425 



and upwards has been received from the Central U'eather 

 Bureau at Melbourne. It has been drawn to the same 

 scale as that of New South Wales (published last year), 

 the two forming a comprehensive and valuable rain-chart 

 of the south-eastern portion of Australia. The average 

 rainfall of Victoria is 27-19 in., ranging from 1080 in. 

 in the Mallee district (north-west) to 68-75 '"• in Cape 

 (3tway Forest district (south). The map shows an approxi- 

 mate distribution as follows : — 4a-> 60 in. over an area 

 of 12 thousand square miles ; 20-40 in. over 43^ thousand, 

 and < 15-20 in. over 32^ thousand square miles. The great 

 influence of proximity to the mountains and seashore is 

 plainly shown ; the abundant rains on the Australian Alps, 

 ('a(>e Otway, and Gippsland ranges being particularly con- 

 spicuous. 



In a paper read before the Royal Photographic Society, 

 Mr. Chapman Jones dealt with the relationship between 

 the size of the particle and the colour of the image in 

 the case of lantern-slides developed to show a coloured 

 deposit. The author referred to Zsigmondy's statement 

 that the colour of colloidal solutions has no direct depend- 

 ence upon the size of the particle, and his suggestion that 

 the cause of the colour is not to be sought for in the sizes 

 of the particles, but rather in the distances between them. 

 Mr. Chapman Jones has investigated the matter, not by 

 the usual ultramicroscopical method, but by enlarging 

 the particles by mercurial intensification. Mercury is 

 added in definite proportions by treating the film contain- 

 ing the particles first with mercuric chloride and then with 

 a ferrous oxalate developer, each treatment adding one 

 atom of mercury to each atom of silver, or of silver and 

 of mercury that is present, the linear enlargement for 

 <ight enlargements, the maximum employed, being 7-134. 

 The enlarged particles were then measured by means of a 

 microscope and eye-piece micrometer, the accuracv of 

 measurement being about 5 per cent. The results obtained 

 showed that films that gave the same colour contained 

 particles of approximately the same diameters, particles 

 below o-io micron giving no visible colour; particles from 

 o-io to 0-13, yellow; from 0-14 to 0-17, orange; from 

 0-17 to 0-19, pink, brown, or purple; and particles above 

 this size, grey. No connection between the distance apart 

 of the particles and the colour was found, but a measure- 

 ment of the refractive index of gelatin and calculation of 

 the half wave-length of light in gelatin, showed that the 

 size of the particle giving a definite colour could be taken 

 to correspond approximately with the half wave-length of 

 light the absorption of which would give that colour, the 

 particles being rather smaller than the calculated half 

 wave-lengths. The authors conclusions are that the size 

 of the particle is the determining factor in selective 

 attering, and that light is scattered by particles that 

 cii>proximate in diameter to half a wave-length of the 

 scattered light. 



Himmel und Erde for April 39 contains an article by 



• >f. B. Donath, of Berlin, on the gyrostat and its 



hnical future. After explaining the precessional motion 



a gyrostat by means of the ordinary toy, Prof. Donath 



gives an account of Schlick's application of the gyrostat 



to the diminution of the rolling motion of ships, and hints 



that a similar device may in the future form part of the 



equipment of the aeroplane. The greater part of the 



article is devoted to the applications of the gyrostat to 



mono-rail transport by Brennan and by Scherl, and to the 



gyrostatic compass by the brothers Anschiitz. In the case 



of the compass, the theory is clearly explained, and views 



of the various parts of the instrument are given. The 



author is naturally optimistic as to the future of the com- 



NO. 2169, VOL. 86] 



pass, but expresses himself more guardedly as to that of 

 the mono-rail. 



The opportunity for the dissemination of nature know- 

 ledge offered by the boy scout organisation should not be 

 lost sight of by those who desire to see the study of 

 natural phenomena become more popular in the future 

 than it has been — unfortunately for us and for our boys 

 and girls — in the past. A lecture recently delivered in 

 Leeds by Mr. Elgie was, according to The Leeds Mercury, 

 attended by some 400 of the scouts, who paid enthusiastic 

 attention to the lecturer's instruction as to the apparent 

 movements of the stars, their grouping in constellations^ 

 and the simpler methods by which geographical direction 

 may be ascertained from observation of the heavens. 

 These same subjects are, we understand, also dealt with 

 by Sir Norman Lockyer, in an additional chapter, in the 

 new edition of his "Primer of Astronomy"; in this 

 chapter the author shows the disposition of the most easily 

 recognised asterisms throughout the year, so that the scout 

 may, on recognising any group of stars, determine at once 

 the cardinal points, and so find his direction. Workers in 

 other fields of science, e.g. geology, botany, &c., might 

 usefully give a little time to the simple instruction of the 

 young people already so admirably organised by the general 

 movement. 



The Cairo Scientific Journal for April contains a paper 

 on work under compressed air at the Boulac Bridge, read 

 by Mr. Arthur J. Knowles before the Cairo Scientific 

 Society on March 2. The Nile at Boulac is very deep ; in 

 places there are more than 66 feet of water at low Nile. 

 The number of men who actually worked in compressed 

 air during the sinking of the piers and abutments of the 

 bridge was 493. One hundred and fifteen cases of illness 

 were dealt with by the doctor, one man being attacked 

 three times, thirteen men twice (one fatally), and eighty- 

 six men were attacked once (three fatally). One case 

 resulted in total deafness, four were fatal, and the remain- 

 ing cases completely recovered. Two of the fatal cases 

 were due to the heart and circulatory system, one to the 

 lungs, and one to haemorrhage of the spinal marrow. 

 The majority of the cases were of pains, cramp, slight 

 palsy, and temporary paralysis of limbs and joints. The 

 labourers were all natives of Egypt, supervised by 

 Europeans, but the latter were not in the compressed air 

 for such long periods as the labourers. The author regrets 

 the non-provision by the contractors of a medical air-lock, 

 into which men suffering from the effects of too rapid 

 decompression can be put and recompressed. This remedy 

 is almost universal in English and American practice, and 

 has been attended with great success. 



Tjie Cambridge University Press announces for early 

 [)ut)li(ation in the series of " Cambridge Manuals of Science 

 and Literature " " Aerial Locomotion," by Messrs. E. H. 

 Harper and A. Ferguson, and " Electricity in Locomotion," 

 by Mr. A. G. Whyte. The first-named work will contain 

 an introduction by Prof. G. H. Bryan, F. R.S., and chapters 

 on general principles, propellers and motors, stability and 

 control of aeroplanes, model aeroplanes and gliders, aero- 

 planes, dirififibles, &c., and Mr. Whyte in his volume will 

 give an account of tht; application of electricity to locomotion 

 and show the present condition of affairs and the develop- 

 ments which may be looked for in the near future. There 

 arc to be chapters on the mechanism of the overhead and 

 of the " stud " systems, on electric railways and on electric 

 traction on main line railways. There will also be a dis- 

 cussion of petrol-engine electric power. 



The age of Sir Nathan Bodington, given in N.ature of 

 last week as eighty-two, was sixty-two years. 



