The philosophy of natural history / by William Smellie ; with an introduction and various additions and alterations intended to adapt it to the present state of knowledge by John Ware.

  • Smellie, William, 1740-1795.
Date:
1827
Catalogue details

Licence: Public Domain Mark

Credit: The philosophy of natural history / by William Smellie ; with an introduction and various additions and alterations intended to adapt it to the present state of knowledge by John Ware. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    materials for their support, but the power of altering the nature of those materials and appropriating them to their own use, is peculiar to themselves. The junctions of living systems are not only performed without the assistance of the physical powers ol matter, but often in direct opposition to them ; and the sub- stances which are introduced into them, lose their chemical relations, and are combined according to new laws, and for new purposes. This power of insulation, possessed by living systems, is in no instance more strikingly evinced, than in the possession by animals of a certain degree of vital heat, which they preserve under all circumstances, short of those which impair or destroy the texture of their parts. This degree of heat—which in man is about 98° of Fahrenheit's thermometer—continues nearly the Mime, even when we are exposed to the most intense cold, and is but little elevated, when we are subjected to a heat above that of boiling water. In many countries, in which the degree of cold is for many months in the year very much below the freezing point of mercury, men not only exist, but enjoy all the comforts of life. In some high latitudes, Europeans have been exposed to temperatures as low as -50° or even -G0° of Fahren- heit's thermometer, that is, to a cold 150° below the natural standard of animal heat, and have escaped every ill consequence. Very lately the whole of two ships' crews wintered in about 75° of north latitude in perfect safety, where the temperature of the air was, for many weeks together, almost constantly below 30°, and where they became so accustomed to severe cold, that the atmosphere, when at zero, felt mild and comfortable. On the other hand, in many countries men exist without difficulty under1 a high degree of heat. In Sicily, during certain winds, the thermometer has been observed at 112°, in South America by Humboldt at 115°, in Africa at 125®. But, for a limited period, much higher degrees of artificial heat have been borne with- out injury. Individuals have exposed themselves voluntarily to the air of ovens at temperatures from 260° to 315° of Fah- renheit's thermometer, without any great inconvenience, while water was boiling and meat baking in the same atmosphere. These facts show a power of resisting the operation of external causes, which is possessed by no substances except such as are endowed with life, and is, probably, possessed in some degree by all that are. For, although vegetables and the lower orders of animals are not capable of resisting to the same extent the influ- - of heat and cold, yet they all show, in some measure, the