Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1804 edition. Excerpt: ... CHAPTER IX. I HAVE dwelt 90 long on these preliminary disquisitions, that I may well seem to have kst sight of the principal object. But I have seized the occasion to set before my readers a variety of physical views, some of which are new, and all of them remote from common apprehension. Notwithstanding their apparent subtlety, however, they will, I trust, be found on reflection to be upon the whole solid and important. They will facilitate on? progress, render our fu ture reasonings more intelligible, and enable me to abridge the thread of investigation. I now return to consider the Nature of Heat. It is almost superfluous to remark, that the term heqt. is of ambiguous import, denoting either a certain sensation, or the external cause which excites it. This last sense only we have to consider. Our feelings furnish a most imperfect notice of the measure of heat: indicating merely the the impression made upon the human organs, they depend on the relative temperature and condition of our body, the quickness or slowness of communication, the particular quality of the contact, and a variety of other circumstances. A substance of the same warmth as the hand, feels agreeable; as it grows continually hotter, the corresponding sensation grows more intense; and at length becomes absolutely painful, and would terminate in the destruction of the nervous fibrils. Suppose the procedure to be reversed, by constantly abstracting the heat, or, in common language, exposing the substance to cool; the impressions of touch will then be throughout of the same kind. The feeling is at first only unpleasant, then grows more and more painful, till the sentient organ at last becomes numb, and is destroyed. The extreme sensations are thus in both easel...
