April 15, 1886] 



NATURE 



559 



to regret that he appears to view with suspicion the competency of 

 the scientific department of the Fishery Board to try it. Perhaps 

 it may serve to reassure him on this point to learn that these 

 suspicions are not in any way shared by the Government, who 

 have now furnished the means for purchasing a steam-vessel for 

 trawling; for maintaining three laboratories (one of them with 

 a large number of tanks) ; and for securing the assistance of three 

 skilled naturalists who will work in conjunction with Profs. 

 Ewart and Mcintosh, to whom y nir contributor alludes. 



S. F. B. 



Protective Influence of Black Colour from Light and Heat 



The difficulty of explaining the black colour of races near the 

 Equator has long been felt. Strong sunshine undoubtedly tends 

 to darken the skin ; but if black, as generally supposed, is the 

 colour that absorbs most heat, natural selection should have 

 developed white as the complexion best adapted to shield man- 

 kind from the intense radiation of an equatorial sun. 



Without venturing to offer an opinion on the subject, I should 

 like to mention three cases that have come under my personal ob- 

 servation, in which brown-skinned natives, in very different parts 

 of the world, blacken their faces to protect them from intense 

 light and heat. 



In Morocco, and all along the north of Africa, the inhabitants 

 blacken themselves round the eyes to avert ophthalmia from the 

 glare off hot sand. 



In Fiji the natives, who are in the habit of painting their faces 

 with red and white stripes as an ornament, invariably blacken 

 them when they go out fishing on the reef in the full glare of 

 the sun. 



Lastly, here in the Sikkim hills the natives blacken themselves 

 round the eyes with charcoal to palliate the glare of a tropical 

 sun on newly fallen snow. 



This I had an opportunity of experimenting on, We were 

 caught in a snowstorm at an elevation of 10,000 feet ; when it 

 subsided all the coolies blackened their eyes, so I had one eye 

 blackened, the other left natural, and went out into the sun for 

 half an hour. I cannot say that I felt much difference. Next 

 day I tried marching for about six hours, up to 12,000 feet, with 

 both eyes blackened. I cannot say how far this may have been 

 palliative, but the glare was so bad, we were all very glad when 

 the mist came up and obscured the sun. Radiation is far more 

 intense at high altitudes than at low levels. Still it is impos- 

 sible to suppose that three such different nations would have 

 adopted the same device to mitigate sun glare if black colour 

 did not give some palliation at least. 



Here then we have one of those strange anomalies in which 

 physiological experience contradicts the teachings of pure 

 physics. Charcoal black, which is used in physical experiments 

 as the best absorbent of every kind of heat radiation, is prac- 

 tically used by three races at least, to protect one of the most 

 sensitive human organs from reflected light and heat. Of course 

 I cannot offer any explanation, but bring the facts to the notice 

 of those who have the skill and opportunity to make physio- 

 logical experiments, in the hope that they may perhaps find a 

 clue to the long-sought-for explanation of the colours of the 

 human race. Ralph Abercromby 



Darjeeling, March 15 



Pumice on the Cornish Coast 



About a month ago I picked up on Maenporth Beach, near 

 Falmouth, apiece of drift pumice of the size of a large goose's 

 egg. It was rounded, floated heavily, and was just twice the 

 weight of a piece of Krakatab pumice of the same size which had 

 been obtained in the Indian Ocean several months after the 

 eruption. No Cirripedes, Serpulas, &c., had attached them- 

 selves to it ; but in one of its crevices I found a tiny dead 

 coleopterous in?ect, which I unfortunately lost. From my 

 familiarity with floating pumice in the Western Pacific I at once 

 perceived that this fragment had been a considerable time in the 

 water. After searching the other beaches in the neighbourhood 

 I failed to find another piece. Mr. John Murray, to whom I 

 sent the specimen, informs me that he has similarly picked up 

 fragments of pumice on the west coast of Scotland. 



Without speculating on the source of the fragment found on 

 the Cornish beach, I should remark that, judging from an experi- 

 ment made in the We-tern Pacific, pumice may float for several 

 years on the sea before it becomes sufficiently sodden to sink to 



the bottom. I kept floating in sea-water for two years and nine 

 monihs three pieces of pumice which I originally obtained in the 

 tow-net whilst cruising in the Solomon Islands. Although they 

 had evidently been a long time in the water before I got them, 

 since they floated heavily and had in two cases the tubes of 

 Serpulce attached, the only apparent alteration in their buoyancy 

 produced by my experiment was that one which floated in fresh 

 water when I first obtained it now sank. How much longer 

 they would have continued to float in the sea-water I cannot 

 say. From their condition before the experiment they must 

 have been previously floating for even a longer period. 



H. B. GUPPY 

 95, Albert Street, Regent's Park, April 10 



The Connection between Solar and Magnetic Phenomena 



In the discussion which followed the reading of Prof. Balfour 

 Stewart's paper on magnetic declination, at the Physical 

 Society, considerable weight was attached to Carrington's 

 observation of a solar outburst observed on September i, 1859, 

 and the simultaneous occurrence of a movement of the magnetic 

 needles at the Kew Observatory. 



Nearly twenty-seven years have now elapsed since the event 

 referred to took place, and both the sun's surface and the 

 magnets have been under observation thousands of hours since 

 that time. 



Hundreds of magnetic movements similar to that above men- 

 tioned have been recorded since, and I should deem it a great 

 favour if any correspondent would either inform me of the time 

 or time< of similar outbreaks to that seen by Carrington, if such 

 have been observed, or refer me to any published accounts of the 

 phenomena. 



Carrington's paper is published in the Monthly Notices of the 

 R.A.S. vol. XX. p. 13. G. M. Whipple 



Kew Observatory, April 12 



Aurora 



A BRIGHT Polar light was observed here on March 30 from 

 8 to II o'clock p.m., how long it had lasted I cannot tell. At 

 8 o'clock only flashes of a pale blue were seen about the 

 Pleiades; their brightness was changing very quickly; at 11 

 o'clock across the whole northern sky there lay the well-known 

 dark segment with the bright arch above ; from the latter only 

 a few reddish beams of light were seen emerging. 



Konigsberg i. Preussen H. Fritsch 



Was it an Earthquake? 



Yesterday morning (Thursday, April 8), at 5.35, the door 

 of my room vibrated regularly for about three or four seconds. 

 I did not perceive any motion of the room itself. I was up at 

 the time, and quite still. Perhaps the best way of finding out 

 whether anyone else experienced anything of the same nature, so 

 as to determine whether it was in any way connected with an 

 earthquake, is to write to Nature. 



Ladbroke Gardens, W., April 9 A. Trevor Crispin 



" Radical " or " Radicle " 



Mr. Madan in his amusing letter last week (p. 533) raises a 

 point which has doubtless often caused the comments of teachers. 

 I think "aparlical of reasoning" at least can be adduced in 

 favour of "radical." In this paradoxical world it is not sur- 

 prising to find that "radical" is the "conservative" and "con- 

 stitutional " spelling, and that " radicle " is a radical alteration 

 in a centenarian word. For next year will be the hundredth 

 anniversary of what was, if I am not mistaken, the first use of 

 the word by Guyton de Morveau. It seems to have long 

 retained its French spelling, and I think it would be a pity to 

 alter one which thus recalls to the memory a host of great 

 names, and perhaps more than any other single word in che- 

 mistry suggests the international brotherhood of scientific men. 

 Of course Mr. Madan's protest has force from the grammatical 

 point of view; it may also be urged that " radicle " is English 

 for the French "radical." But from the chemical standpoint 

 surely the "radical" is as much a "stem" as a "root"? For 

 instance toluene is either CoHsCCHj), or CH3(C„H5), and it 

 would be arbitrary to select from a very limited number of 

 reactions the "root" in prussic acid, H.CN, C.NH, or 



