Page:Proceedings of the Royal Society of London Vol 1.djvu/48

Rh as high as the elbow, while in some cases even the wrist of the other hand will experience a similar sensation.

It has been ascertained by repeated trials, that these effects are stronger in proportion to the greater distance of the metallic pairs, which are made to communicate. Some sensation will be produced when the foot of the column is connected with the third or fourth pair, but it will perceptibly increase as we proceed further towards the summit. This naturally led to an extension of the column much beyond the number of metallic pairs above mentioned; and expedients are here suggested for rendering such extended columns stable and at the same time sufficiently manageable. With a column of about sixty pairs of plates, shocks have been felt as high as the shoulder; such a column may be even divided into two or three distinct cylinders, which being well connected by metallic conductors, will be equally powerful and much more convenient.

Among various other modes of applying the same agents, the author describes an apparatus in which the ﬂuid is interposed between the metals without being absorbed in a spongy substance. This consists of a number of cups or goblets, of any substance except metals, placed in a row either straight or circular, about half filled with a saline solution, and communicating with each other so as to form a kind of chain, by means of a sufﬁcient number of metallic arcs or bows, one arm of which is of silver, or copper plated with silver, and the other of zinc. The ends of these bows are plunged into the liquid in the same successive order, namely, the silver ends being all on one side, and those of zinc on the other,—a condition absolutely necessary to the success of the experiments, it having been observed that if out of sixty bows, for instance, the twenty intermediate ones he turned in the opposite direction from the remainder, the effects produced by the apparatus will be far less perceptible.

It was observed, that if a circular communication be completed by means of a bow connecting the ﬁrst and last of along series of cups, two hands, or even two ﬁngers plunged into one of these cups will still receive an electric sensation. This is explained by admitting the fact, that warm animal substances, and particularly their ﬂuids, are in general better conductors than water.

The sensible effects of either of these apparatus, composed of forty or ﬁfty links, do not, it seems, consist merely in shocks, contractions, or spasms in the muscles or limbs; but, besides affecting the sense of touch, they are also capable of exciting an imitation in the organs of taste, sight, and even hearing. A particular account is given of these singular effects, from which we learn, that the more sensible the parts are which are exposed to the impressions of this agent, the more quick will be the sensation;—that as to taste, we have only to recollect the experiments formerly described by the author, in which the tongue was sensibly affected by the combination of two metals applied to each side of it;—that with respect to the sense of vision, the sparks yielded by this apparatus are sufﬁcient evidence of the effect, certain expedients only being necessary for facilitating the