Volume 1

Observations on man, his frame, his duty, and his expectations. In two parts / By David Hartley.

  • Hartley, David, 1705-1757.
Date:
1749
Catalogue details

Licence: Public Domain Mark

Credit: Observations on man, his frame, his duty, and his expectations. In two parts / By David Hartley. Source: Wellcome Collection.

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131/552 (page 99)
Anatomifts, then one would imagine, that the homo¬ nymous Nerves of the right and left Sides mult, in croiTing over, lie fomewhere contiguous to each other, and fo impart Vibrations to each ether. And there feem to be fome Fadts from whence this may be in¬ ferred; but we cannot expect to be able to diftinguifh, with Certainty, fo feeble an Influence, amidfl fo many others that are far flronger. Yawning and Stretching may, perhaps, whencon- fidered in all their Circumitances, take in all the Five Claflfes of motory Vibrations. When they happen in the Attacks of Fever-fits, and other morbid Cafes, the firfl feems to be owing to pretty hidden and flrong Contractions in the Membrane of the Mouth, Fauces, Afpera Arteria, and Oefophagus ; the laft to Contrac¬ tions in the whole Skin. As the Bowels derive their periftalnc Motion, in part, from the Second and Third ClaiTes, fo it feems, that the fecretory and excretory Veffels of the Glands mull be conflantly agitated with a like Motion, from the fame Caufes, performing their ordinary Secretions and Excretions thereby. Their extraordinary ones are generally owing to Irritations in the Membranes, in which the Mouths of their excretory Veffels lie. And this agrees remarkably with the Doctrine of Vibra¬ tions. For the vivid Vibrations excited in the Mem¬ branes by the irritating Caufe muft diffufe themfelves every Way •, and when they come to the Mouths of the excretory Veffels, penetrate them, and, by paffing ; up into the Veffels, both excretory and fecretory, greatly increafe their periftaltic Motion, and, by Con- fequence, their Secretions and Excretions. All this feems equally to hold, in refpedt of the exhaling and abforbing Veffels difperfed throughout the Body. The external Motions of the Eyes in young Chil¬ dren are probably owing, in part at leaf!, to the im¬ mediate Adtion of Light upon the tendinous Expansions of the Four ftrait Mufcles, and particularly upon FI 2 thole