The nice excess of pressure or distention, as when the purpose of a pin is pressed upon our pores and skin, produces pain, (and when this pain of the sense of distention is slighter, it’s termed itching, or tickling), without any concept of solidity or of determine: an excess of heat produces smarting, of chilly another form of ache; it is possible by this sense of heat the ache produced by caustic bodies is perceived, and of electricity, as all these are fluids, that permeate, distend, or decompose the parts that really feel them. And it is probable from the unfastened bones, that are found within the heads of some fishes, that the vibrations of water are smart to the inhabitants of that aspect by an analogous organ. Coming from an African household (from Ivory Coast), mama all the time advised me that my closing happiness can be to found a husband and that not having one would put a shame on me and the household. If one edge of a plate of silver about the dimensions of half a crown-piece be positioned upon the tongue, and one edge of a plate of zinc about the identical dimension beneath the tongue, and if their opposite edges are then brought into contact before the purpose of the tongue, a style is perceived in the mean time of their coming into contact; secondly, if one of the above plates be put between the higher lip and the gum of the fore-teeth, and the other be placed beneath the tongue, and their exterior edges be then brought into contact in a darkish room, a flash of mild is perceived in the eyes.
Hence, when they are positioned in the way above described, as quickly as their exterior edges come almost into contact, so near as to have an especially skinny plate of air between them, that plate of air turns into charged in the identical method as a plate of coated glass; and is at the identical immediate discharged via the nerves of style or of sight, and provides the sensations, as above described, of gentle or of saporocity; and only shews the great sensibility of these organs of sense to the stimulus of the electric fluid in immediately passing by means of them. From the experiments above talked about of Galvani, Volta, Fowler, and others, it seems, that a plate of zinc and a plate of silver have larger effect than lead and silver. There are numerous experiments in chemical writers, that evince the existence of heat as a fluid element, which covers and pervades all our bodies, and is attracted by the solutions of some of them, and is detruded from the mixture of others.
The entire set of muscles, whether or not they are hollow ones, as the guts, arteries, and intestines, or longitudinal ones hooked up to bones, contract themselves, at any time when they are stimulated by forcible elongation; and it’s observable, that the white muscles, which constitute the arterial system, seem to be excited into contraction from no different kinds of stimulus, in response to the experiments of Haller. All these motions of the muscles, that are thus naturally excited by the stimulus of distending bodies, are additionally liable to be known as into robust action by their catenation, with the irritations or sensations produced by the momentum of the progressive particles of blood within the arteries, as in inflammatory fevers, or by acrid substances on other smart organs, as within the strangury, or tenesmus, or cholera. These are concepts of suggestion, which we feel or attend to, associated with the motions of the retina, or irritative concepts, which we don’t attend to. Hunger is most likely perceived by these numerous ramifications of nerves which might be seen in regards to the higher opening of the stomach; and thirst by the nerves concerning the fauces, and the top of the gula. Thus an incredible excess of gentle does not give the thought of gentle but of pain; as in forcibly opening the eye when it is far inflamed.
We might add, that even the exterior opening of the ear is just not completely necessary for the notion of sound: for some folks, who from these defects would have been fully deaf, have distinguished acute or grave sounds by the tremours of a stick held between their teeth propagated along the bones of the top, (Haller. These seven last mentioned senses could properly be termed appetites, as they differ from those of touch, sight, hearing, taste, and odor, on this respect; that they are affected with ache as well by the defect of their objects as by the surplus of them, which isn’t so in the latter. And on this the notion of heat essentially differs from the perceptions of the sense of touch, as we obtain pain from too nice pressure of stable our bodies, however none from the absence of it. The instant object however of the sense of vision is mild; this fluid, although its velocity is so great, seems to have no perceptible mechanical impulse, as was talked about in the third Section, but appears to stimulate the retina into animal motion by its transmission by means of this part of the sensorium: for although the eyes of cats or different animals seem luminous in obscure locations; yet it’s probable, that none of the light, which falls on the retina, is reflected from it, however adheres to or enters into mixture with the choroide coat behind it.