274 



- KNOWLEDGE 



[Nov. 2, 1883. 



THE GREEN SUN IN INDIA. 



By Richard A. Proctor. 



FURTHER letters from Ceylon show that the green or 

 blue sun was only seen there (at least as a marked 

 phenomenon) from the Kth to the 12th September inclusive. 

 The Ceylon Observer contains some interesting communi- 

 cations on the subject. One correspondent, writing on 

 September 12 from Puleadierakam, states that no light 

 came from the sun, though he was visible, until nearly 

 seven in the morning. " For the last four days," he says, 

 " the sun rises in splendid green when visible — that is, 

 about 10 deg. from the horizon. As he advances he 

 assumes a beautiful blue, and as he comes further on he 

 looks like a brilliant blue, resembling burning sulphur. 

 When about 45 deg. high it is not possible to look at the 

 sun with the naked eye ; but, even when at the very 

 zenith " (meaning, no doubt, the hiohest point of his path, 

 near, but not absolutely at, the zenith) " the light is blue, 

 vajying from a pale blue early to a bright blue later on, 

 almost similar to moonlight even at midday. Then as he 

 declines the sun assumes the same changes, but vice versd. 

 The heat is greatly modified, and there is nothing like the 

 usual hot days of September. The moon, now visible in 

 the afternoon, looks also tinged with blue after sunset, and 

 as she declines assumes a most fiery colour 30 deg. from the 

 zenith." It is rather singular that the moon when nearing 

 the horizon should have assumed a fiery hue, while the sun, 

 when in the same position, looked blue. This seems to 

 show that though the moon looks white, there is really a 

 certain degree of ruddiness in her surface tints. 



As to the explanation of the changed tint of the sun, a 

 few points are clear. It is obvious that the absorptive 

 medium whose action gave to the sun its bluish-green tint 

 was in our own atmosphere, not in the sun himself. As 

 the sun was seen blue at Trinidad on September 2, it 

 seems probable that the Java earthquake had nothing, or 

 little, to do with the sun's peculiar tint in India and 

 Ceylon ; for the blue sun of Trinidad cannot possibly have 

 been caused by the Java disturbance. The spectroscopic 

 evidence seems to show that the greenness of the sun was 

 due to an exceptional development of the rainband in the 

 red part of the spectrum (the exact position of the band is 

 shown in a diagram illustrating an article by Mr. J. Brown- 

 ing in Kn'owledge (Xo. 102, p. 230). Thus was occasioned 

 an abnormal absorption of red and orange-red rays, leaving 

 a superabundance of rays from the rest of the spectrum, 

 and, consequently, a tint of green. 



It is noteworthy that an explanation advanced in Nature 

 (whose editor is supposed to know something about spec- 

 trum analysis) by Mr. W. R. Manley, principal of the 

 High School of Madras, is entirely incorrect. He finds in 

 the circumstance that the colour of the sum varied after 

 the order of the colours of the solar spectrum, evidence 

 that there was some refracting medium in the atmosphere 

 which resolved the sun's rays into primary colours. This 

 would not account for the sun appearing green. There is 

 no sort of prism which will show the sun green, or blue, or 

 red, let the refracting quality of the medium be what it 

 may. Seen through any prism whatever the sun would 

 simply show rainbow-tinted fringes on opposite sides of a 

 central and not quite circular white disc. Absorption was 

 manifestly the cause of the sun's colour, not simply refrac- 

 tion — though refraction, of course, took place (as it always 

 does). 



A correspondent calls attention to the circumstance that 

 in the Arctic regions the sun often shines with a pure 

 emerald-green tint all through the day. — Xevxastle Weekly 

 Chronicle. 



TRICYCLES IN 1883. 



By John Browsing, 



Chairman of the London Tricycle CUtl. 



THE "Carrier" just introduced by Messrs. Singer ifc 

 Co. bids fair to bring the tricycle into still more 

 general use in the Imsiness of everyday life. It is of very 

 novel construction. Though a hind-steerer, it is a double- 

 driver, both wheels working with one chain and a balance- 

 gearing. The sides of the hay-fork frame are carried 

 forward in front of the rider, and between them is sus- 

 pended a large square wicker basket of a capacity of= 

 from forty to fifty cubic feet. The machine is contrived so- 

 that no more weight is thrown on the hind steering-wheel 

 than is just necessary to ensure good steering. 



Evidently such a tricycle could be used with advantage 

 instead of a horse and cart, to send out newspapers in 

 bulk to the trade, or for the delivery of a number of light 

 parcels. In country districts it would probably be service 

 able to the Parcels Post. 



The " Carrier 



The machine has wheels from 4G in. to 48 in. diameter, 

 geared down to about 36 in. The value of such a machine- 

 would be increased tenfold if it were provided with a 

 good two-speed gearing. The wheels should be 40 in., 

 geared to run level. As it it necessarily a somewhat 

 heavy machine, and will mostly be used in places of con- 

 siderable traflic, it would not be required to be driven at 

 a high rate of speed. The power-gearing should run at 

 about 2.5 in. to enable the rider to work with a heavy load- 

 over muddy or rough roads, up hills, or against a high 

 wind. 



As the machine is now made I have driven it with great 

 ease carrying between 1601b. and 1701b. in the basket oni 

 level crround. 



The " Tr.wellek." 



The "Traveller " tricycle, brought out by the same firm^ 

 does not possess the same amount of novelty as the 

 " Carrier," but it may prove of considerable value as a fast 

 machine. It is a modification of the well-known "Humber," 

 but the alterations are neither few nor unimportant The 

 double-driving-gear is reduced to about the size of a small 

 tin blacking-box, being only about half the length of that 

 on the usual "Humber." The pivots on which the front 

 wheels swivel in steering (marked P on the block) are 

 arranged in the form of a Stanley head, and are brought 

 some distance behind the handle-bar towards the saddle 

 of the rider. This, it is stated, diminishes the great 



