Dress, with reference to heat : being a lecture written for, and published by the Australian Health Society / by Walter Balls-Headley.
- Balls-Headley, Walter.
- Date:
- 1876
Licence: Public Domain Mark
Credit: Dress, with reference to heat : being a lecture written for, and published by the Australian Health Society / by Walter Balls-Headley. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![people of the south of France, who are dark-haired ; in tliose of Italy, who are dark-complexioned, so that a red-haired girl is a curiosity to them ; while the Spaniards are olive-complexioned ; the Moors, Asiatics and American Indians more or less copper- coloured ; and the Central Africans, Australian Aborigines and Samoans tolerably black. The cause of this appeai-ance is due to the production in the skin of a more or less thick layer of pigment cells, in character resembling those of the eye ; where the iris of the Albino is without colour, and of another person black. Why is it, that the animals of a very cold climate turn white in winter, while indeed some, as the men and Polar bears, are always white ; and that those people and creatures, which inhabit a hot climate, are dark : while ci'eatures inhabiting the Northern seas are not white, nor change their colour? The answer is I think obtained from a considei-ation of two points. The first is the action of the pigment of the eye. This membrane lines the interior of the eye, and its function is to absoi'b all rays of light, not otherwise required. Accordingly we find that Albinoes, who have pink eyes, being without this pigment, see best in a dull light. Now, by the correlation of forces, light is equivalent to heat; as, for example, we know that, when we have most light from the sun, we have most heat. Thus black or darker colors are capable of absorbing an amount of heat much greater than white or lighter colours. The second point is derived from the experiment of ])lacing a thermo- meter under and touching a i)iece of black flannel, exposed to the sun's rays. In one such experiment, which may be taken as a fiiir sample, the temperature in the sun was 86 deg. ; but when the black flannel was ])laced over and close upon it, the heat was found to be 98 deg., that is 12 deg. higher; while, if an interA-al of air was left between the two, it fell to 83 deg. Now taking man in the cold climate; if his body, or, in the case of the animal, its fur, which is part of itself, were black, from immediate contiguity a large amount of heat would be drawn from the body, and at once absorbed by the colouring matter of the skin : but evaporation, as has been shown, is constantly in process; and it would follow, from the moisture attracted to the surface by this lieat, that a constant and](https://iiif.wellcomecollection.org/image/b2227215x_0017.jp2/full/800%2C/0/default.jpg)
