cautery, "or to burn the nerve," as they call it, and have at times complied. But a great drawback to the successful performance of this operation has always arisen from the necessary fineness of the wire required, which, before it can be inserted into the foramen of the tooth, becomes too cold, and the consequence is, violent inflammation like that following a burn is set up, instead of effecting the immediate and total destruction of the pulp, or dental nerve; whereas the platina wire, heated by electricity, is applied at the fullest heat at once.

Among the many methods made use of by the profession of applying the actual cautery, the coolest, I think, in one sense at least, is that adopted by Mr Kocker, and recorded in his work entitled, "Principles of Dental Surgery," published in the year 1826.

"I require," he says, "for this the following apparatus:1st, A small iron wire, fastened to an ivory handle; the extremity of this wire I file to the size of the exposed nerve, and bend the wire in such a direction as to enable me to touch the tooth or mouth.

"2d, A thick tallow candle, with a large wick. I direct the patient to discharge all the saliva he may have in his mouth, then to incline his head backwards against the head support of my operating chair; I put the candle into his left hand, and direct him to hold it in such a position that the flame of it may be on a level with his mouth."

Some dentists recommend that a sharp wire should be thrust down into the root of the tooth, and then rapidly twisted round, so as to tear out the nerve.

There are advocates for this plan, who declare that there is not much pain in so doing, but that it is an operation rather pleasant than otherwise. I doubt much if many will coincide in this view of the matter, more especially the party operated upon.

When the actual cautery is considered necessary in cases of alveolar hemorrhage, the importance of this instrument, heated by electricity, I think will be appreciated, as the point of the bleeding vessel may be touched with a wire at a white heat, while no other part of the mouth is affected.

The method of applying the actual cautery, which I have now to explain, was suggested to me by seeing the article in the "Lancet," vol. i., for 1851, page 546, in which a proposal was made for excising tumours, &c., by means of wire brought to a white heat by electricity.

I have followed up the idea, and the instrument on the table is the result, and has been in operation since that period.

After several experiments (assisted by Mr Stevenson), I found a battery after "Grove's" plan answered best, being more convenient than Smee's. It is much smaller, and consequently more portable and more easily kept out of sight.

By one pair of plates I can produce a more decided result than I could with six pairs of "Smee's."

In the glass vessel I have a mixture of four parts of water to one part of concentrated sulphuric acid.

In the porous jar there is a mixture composed of two parts of nitric to one part of sulphuric acid.

At the end of each of the conducting wires you will observe a fine platina wire brought to a point. This wire is fine enough to enter the foramen of any tooth; but where it is used to cure toothache, the merely passing the wire round the decay is sufficient, or for the larger cavities the wire can be rolled up as a small ball.

When the wire is to be heated, the communication is made by gently pressing upon the ivory knob, which pressing down the spring, the contact is at once made.

By taking off the pressure the current is broken off as quickly.

At first I found some difficulty in operating, from the want of elasticity in the wires, as the thickness necessary to convey the electricity sufficient to heat the wire, rendered them very unwieldy.

This was overcome by a plan of my son's, which consisted in filling two small india-rubber tubes with quicksilver, the ends of the copper wires being inserted into the mercury at both ends, and tightly tied. By this means the communication was rendered complete, and allowed of freer motion. Since this was done, we find now full freedom can be ob

tained by using a string of very fine wire tied together, instead of a single thick one.

The advantages, then, to be obtained by this instrument are, its easy application to the desired spot in the mouth, and that perfectly cold, instead of alarming the patient by holding a red-hot iron before his face; its being at once raised to the requisite heat, and no more than the mere point of the wire used being heated; also from its being at once cooled on simply removing the finger from the spring; and, lastly, there being no appearance of heat to alarm the patient.

If applied for the purpose of arresting hemorrhage, or the deadening of the dental nerve, the cavity should be first well dried out with a piece of lint, and then the desired spot should be rapidly touched, so as not to come into contact with other parts. This can be repeated, if found necessary. The platina must be at least red-hot, as it then acts effectually and instantaneously, and really with little or no pain; otherwise, if not heated sufficiently, it would cause much pain and subsequent inflammation. I need not say, with timid persons the inhalation of chloroform should be resorted to.

I may, in passing, mention, that I have used this instrument in many cases with and without chloroform. I may instance one case without chloroform. A young gentleman, of about nineteen years of age, came to me (now some months ago) to have a front tooth of the upper jaw stopped; and while engaged in scooping out the decayed bone, previous to putting in the gold, from the great pain he was suffering (although he tried to hide it) he fainted. I made him call next day, and applied the cautery: he felt, he said, a peculiar sensation from its action, but he could not call it pain. The next day again, I stopped it with gold, and he is now quite free from either pain or uneasiness.

With these few remarks, Mr President, I will now conclude, and proceed to show the battery in action, which, I trust, will be thought more available than that of the thick tallow candle of Mr Kocker, or the instrument employed by a Cambridge friend of Mr Tomes of London, who, it seems, was dreadfully tortured with pain in a carious tooth; and that one day,

quite worn out with suffering, he broke off all the prongs of a dinner fork but one; the remaining one he heated red-hot, and in that condition thrust it forcibly into the hole of the aching tooth. The pain, he says, ceased in a moment, and that he has not, from that time to this, a period of nearly thirty years, had a single twinge of the toothache.

It is unnecessary to state to such medical men as may be present this evening, that where suppuration has taken place, the cautery will not be applicable; he must therefore treat the case as circumstances point out as being most proper.

I may mention that when the battery is not in use, the plates should be taken out and washed with water, afterwards to be kept dry. The porous jar must also be taken out, and placed with its contents into the second or receiving jar, and the stoppers put on. By this means the acids are always ready for use, and last much longer, and the unpleasant and destructive nature of the acids is guarded against.

At first, when I only used one glass jar, it was necessary, after being used, to pour the acids into separate bottles, but, from the chance of spilling the liquids, and escape of the acid fumes, it was very troublesome and indeed objectionable; but by the means indicated all this is entirely avoided.

Address delivered by DAVID RHIND, Esq., F.R.S.E., Architect, President of the Royal Scottish Society of Arts, on taking the Chair on 27th November 1854.

GENTLEMEN,-I have to thank you in the most cordial manner for the high honour you have conferred upon me in electing me to succeed your late distinguished President, Professor Kelland, and I have also to thank you in the name of the Vice-Presidents.

Had the success of the Society of Arts, or its progress, depended on the influence and position of its President, I would have felt much diffidence in accepting the high honour your kindness has conferred upon me; but its uninterrupted prosperity and steady career of usefulness for upwards of

thirty years, proves that it is now thoroughly established as one of the permanent institutions of the country. In taking the chair, therefore, it is only necessary for me to express my determination to use every exertion faithfully to discharge its duties, with the hope that at the end of the Session I may have the satisfaction and pleasure of reporting the increasing usefulness of the Society.

I intend as usual to reserve any formal observations I may have to offer until the close of the Session, but meanwhile I may perhaps be permitted, in taking the Chair, to request those gentlemen who have hitherto been in the habit of supplying us with papers, to continue their valuable aid. In particular, I trust the many subjects that have hitherto so largely occupied the business of our meetings, viz., those regarding the safety of railway travelling, the electric telegraph, and other subjects more peculiarly the province of the engineer, will continue to receive a large share of attention. It is not possible to over-estimate the importance of what yet remains to be done for the safety of railway travellers, and it will therefore be for the public interest that this Session should find the gentlemen who during former years have taken up these subjects, still continuing to bring forward suggestions in this department of our labours.

While, however, I think these and other kindred subjects should, as heretofore, receive a large share of attention, I may perhaps be permitted to say, that the selection of an architect for the chair, which I think you have this year done for the first time, would seem to indicate that, during the Session on which we are entering, we will be open to receive papers on subjects connected with building, and also with the different branches of art-manufacture.

It would undoubtedly be of much value both to ourselves and the public, if we devoted some portion at least of the Session to practical subjects connected with building operations, and to an analysis of the results of the Great Exhibition of 1851, as regards art-manufacture. We have all to some extent seen the improvement that has taken place in art-manufacture during the last five years; indeed, it is impossible to have overlooked it, extending as it does to