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
Catalogue details

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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    occurred, after one had jiut on the second pair of stockings outside the boots, whereby much air could be included. Again, in Captain Boyton's swimming apparatus a bag of Indiarubber, or other water-proof material, includes a quantity of air in a state of perfect rest ; which intervenes between the body and the colder watei*, preventing loss of heat by the man. Besides fat, animals have various kinds of hair or fur, dense in proportion to the climate they inhabit and their requirements: being hair in various grades of development. Of such may be mentioned the hair of horses, the wool of sheep and such like, -which increase in length and thickness as the cold affects them, and fall off in the spring. Those animals which live in very cold climates, as the sable, and the seal, which inhabit the Arctic Seas, have a secondary, densely develo^^ed coat nearer the skin, which we call fur. Birds have a form of hair development, which we call feathers; different from that of mammals in being larger and longer; but the transition is gradual, as in the apteryx, the cassowary, the emu, the ostrich and the penguin. The feathers of birds, when lying closely one upon another, are admirable non- conductors, or media for i-etention of heat: and this is increased, as in hair and fur, by the presence of minute quantities of still air, which are retained between them. Watei birds still farther supplement this power by thoroughly, frequently and carefully dressing them with oil; whereby heat retention is still more increased. In some countries too, in which the cold is very excessive, where the surface of the earth is covered with snow, and is thus uniformly white, animals in winter change the colour of their coat and become white, as the hare, the fox and the ptarmigan ; which again, as the summer approaches, become of some kind of ■brown colour. Similarly, we find that the ])eoples who are descended from those of the Northern countries, as ourselves, are, comparatively speaking, white : and that, as you gradually approach the equator or tropical regions, you find the colour of the skin assume a darker hue. Graduations of this kind may be noted in the Swede, the Norwegian and the Saxon, who are fair; in the