a proof of the accuracy of the statement I made, that positive and negative electricity were alternately evolved at both wires. On this account, however useful this apparatus is when we want the mere stimulant action, the simple shock of the electric agent; yet it is likely to fail in certain forms of paralysis, in consequence of our not being able to transmit by its aid the positive current in the direction of the nervous ramifications.

The more elegant and elaborate magneto-electric machine, especially the very effective and powerful one of Mr. Clark's construction, may of course be substituted for the electro-magnetic apparatus I have described. The advantages it presents of being always ready for use, and requiring no initial voltaic current to set it in action, are not, however, I think by any means sufficient to compensate for its expense, and the readiness with which it is disarranged, especially when in the hands of the uninitiated.

To render the electro-magnetic current available where it is required to be transmitted in a definite direction - where, indeed, we want the currents separated as we get them in the voltaic or galvanic battery, without the serious inconvenience attending the use of these pieces of apparatus some modification of the electro-magnetic machine is required. After devoting some attention to the subject, I contrived the machine before you, which

answers the purpose most completely. It consists of the double coils of wire fixed in a box, on the lid of which is placed a wooden cylinder, capable of revolving between two uprights by means of a proper handle. This cylinder is furnished with two slips of brass fixed in the wood at each end, and connected with the metallic axes by which the cylinder is supported in the brass collars of the uprights. The slips of brass are placed so as to alternate with each other at either end of the cylinder. Two elastic brass springs, supported by pillars of that metal, press on the cylinder at either end. The ends of the thick wire of the coil concealed in the box are connected one to the end of one of the supports of the cylinder, the other to a binding-screw fixed in the lid. The zinc and silver plates of a simple battery are then connected with this screw, and with the supports of one of the brass springs. On revolving the cylinder, contact with the battery is of course made or broken, according as the slip of brass or the wooden portion of the cylinder passes under the brass spring. You know that with each of such unions and ruptures of contact, an induced current circulates in the fine coil of wire in the box. The ends of this coil are soldered to the second upright, and the support of the second spring. The pieces of brass being properly arranged, it follows that one kind of current can alone traverse the

conducting-wires fixed to the supports connected with the fine coil. To prove this I will let these conductors, terminated as before with platinum ends, rest on the iodised paper. On turning the cylinder, the iodine is, as you see, set free at one end only. I know, therefore, that the positive electricity escapes by this wire, and the negative by the other. Hence by this instrument we have succeeded in obtaining separate currents, although we have lost the great convenience of the automatic movement of the other apparatus.

Let me now say one word respecting the agent evolved by these different pieces of apparatus. By all of them electricity is excited, and the terms of electricity, galvanism, and electro-magnetism really refer only to different conductions of the same agent.

A,

*Fig. 24. The single-current electro-magnetic machine. the revolving cylinder, with slips of brass inlaid, on which the springs, B, B, press. C, the battery, connected by wires with the screws D, E. FF, the conductors, connected with the screws G G, which are in communication with the fine coil in the box K.

Thus by the common electrifying machine we obtain a small quantity of electricity in a state of high tension or elasticity, capable of effecting a discharge through very imperfect conductors. Electricity is obtained, on the contrary, from the voltaic or galvanic trough in a very different state, its quantity being large, but its tension or elasticity being so slight that it cannot effect a discharge through any but good conductors, a piece of tissue paper being sufficient to resist altogether the passage of a current capable of heating redhot several feet of platinum wire. In the electromagnetic machines electricity is afforded to us in moderate quantity, and in a state of tolerably high tension, still much inferior in this respect to that afforded by the electrifying machine. The currents alternate in direction in the double current machine (fig. 22.), whilst they are in the same direction in the single current apparatus (fig. 24.).

I purpose, next, to direct attention to the results which have followed the employment of the different modifications of electricity in the treatment of disease. In doing this I do not intend to occupy your time by a tedious reference to all that has been previously published on this subject, in this country and on the Continent. Such records are familiar to every physician, and within the reach of everybody who will take the trouble of referring to them. I am more anxious to avail

myself of this opportunity of presenting to the members of the College the results which have fallen under my own personal experience.

Electricity has been by no means fairly treated as a therapeutical agent; for it has either been exclusively referred to, when all other remedies have failed in fact, often exclusively, or nearly so, in helpless cases or its administration has been carelessly directed, and the mandate, “Let the patient be electrified," merely given, without reference to the manner, form, or mode of the remedy being for an instant taken into consideration.

Conscientiously convinced that the agent in question is a no less energetic than valuable remedy in the treatment of disease, I feel most anxious to press its employment upon the practical physician, and to urge him to have recourse to it as a rational but fallible remedy, and not to regard it as one capable of effecting impossibilities. I again say, I shall advance nothing but what has been repeatedly tested under my own observation, purposing to lay before you the results of many years' careful clinical experience in this matter, in the wards of Guy's Hospital; and hope to make out a strong case in favour of this too much neglected remedy.

In the autumn of 1836, the authorities of the hospital thought fit to set apart a room for the