This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1863 edition. Excerpt: ...than the accuracy of the skin in giving notice of changes of temperature; for a difference of one-third of a degree is detected clearly when the hand is immersed repeatedly and successively in two vessels of water, differing only so much in temperature. The skin detects best very minute changes of temperature, ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1863 edition. Excerpt: ...than the accuracy of the skin in giving notice of changes of temperature; for a difference of one-third of a degree is detected clearly when the hand is immersed repeatedly and successively in two vessels of water, differing only so much in temperature. The skin detects best very minute changes of temperature, when the medium examined does not fall short of, or exceed very considerably, the usual temperature of the body. Water at 98 can be much more certainly distinguished by the hand from water at 100, than can water at 120 from water at 118. As the ear perceives best a difference of tone in sounds, neither too high nor too low, or immoderately loud, so the skin judges with most accuracy of medium temperatures, which produce no very violent or painful effect on its nerves. Weber is of opinion that the perception of temperature imparted to each nervous extremity in the skin, goes to unite itself to, and strengthen, simultaneous impressions in the other ramifications of the same nerve, thus producing, by the conflux of a great number of impressions, a much stronger result and effect. This, at least, is certain, that a large surface conveys much stronger impressions than a small one, and estimates changes of temperature with greater delicacy, Thus, if we INFLUENCE OF SUCCESSIVE IMPULSES. 197 place the fore-finger of one hand in water at 104, and plunge the whole of the other hand into water at 102, the latter will appear to us to he the warmer. If we plunge the finger successively into vessels containing hot water, we are unable to perceive very minute differences of temperature, which at once become perceptible when we use the whole hand. Nay, water, which can easily be borne by a single finger, will appear intolerably scalding to the whole hand!...
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