The principles here explained are generally known by well-informed men who are engaged in manufactures, and the example of their application to Argand's lamps ought naturally to lead them to the idea of directing similar currents upon the flame of furnaces, by openings, or particular channels, which can never be stop'ped, in order to supply the insufficiency of the air that passes through the grate, where it is frequently stopped by the slags another disposition still more analogous to these lamps, consists in causing the smoke to pass through a narrow throat, which, from its small surface, and the heat of its sides, would not lower its temperature in any sensible degree, and to which place a continual current of air not disoxygenised may be brought by means of other tubes or channels. Thus the two conditions necessary to combustion, namely, oxygen and a certain temperature, would be united in the current of the smoke, and the combustible materials which are suspended in this smoke would of course be burned.

Messrs. Clement and Desormes being equally versed in the knowledge of natural philosophy, and in the arts, have put in practice, seven or eight years ago, some dispositions of the first sort in a manufactory of green vitriol, established at Paris, near de la Garre, and have made others of the same kind in their manufactories of alum at Verberie. Their connection with M. Montgolfier, a member of this class, had enabled them to assist their conceptions with those of our fellow member. But they have not been the first who have availed themselves of so good a help. It is now two years since M. Champy, junior, who was thinking on the same subject, for his furnace at the gunpowder, works at Essone, had

consulted

consulted with Messrs. Montgolfier and Clement, aud afterwards built, without having seen the establishments of de la Garre and Verberie, smoke-destroying furnaces for the drying houses of the gunpowder works at Essone, with the greatest success.

The constructions of M. Gengembre, of which we have given an account to the class, are, as we have already said, and as he says himself, the result of the knowledge acquired by the labours of Messrs. Clement, Desormes, and Champy. These gentlemen have declared, that when they began to occupy themselves about 'methods of destroying smoke, they did not know of the inventions of Messrs. Roberton and Watt, of which we shall now speak, and we do not hesitate to give credit to their declaration.

It was in 1801, a short time before the first trials of Messrs. Clement and Desormes, that Messrs. Roberton of Glasgow, in Scotland, took out a patent for smokedestroying furnaces. Their process consisted in introducing, immediately over the fire-place, a plate of the external air, the thickness of which may be altered by means of a very simple mechanism, which regulates the distances of two inclined plates of iron between which this plate of air passes. The space between these two plates communicates with the atmosphere by a horizontal opening made above the door, and against which the plates are placed.

Our fellow member, M. Pictet, saw at London a small steam-engine, furnished with this apparatus, of which he has given a description in the Bibliotheque Britannique for 1782, and which perfectly answered the purpose. The late Mr. O'Reilley has since described the

same

same apparatus in the Annales des Arts et Manufac

tures.

It was known, on the other hand, by hearsay, that our fellow member, Mr. Watt, had long before the date of Messrs. Roberton's patent occupied himself on the means of burning the smoke from steam-engines, But we do not believe that he has published his inven tions on that head. At least there is no mention of them in any of the works which give an account of the English inventions that have come to our knowledge *, and as Messrs. Watt and Bolton, who shew with a great deal of complaisance and politeness the working and uses of their engines, are very careful to conceal their internal construction, we should not have had any idea of their method of destroying the smoke, if they had not adapted the apparatus to a steam-engine at Nantes, the several parts of which were got up in their workshops, and which was erected at Nantes in the year 1790, under the direction of our fellow member M. Levêque, who had discussed and arranged the plans with Mr. Watt himself. This apparatus is very similar to that of Mr. Roberton. The principal difference is, that in Watt's engine the current of air is introduced under the grate instead of above it, as in Roberton's engine. The first apparatus is therefore with a direct flame, and the second with a reversed flame. Our fellow member M. Levêque haš assured us that the engine at Nantes does not yield any smoke.

* See the various volumes of this work.

No Patents passed the Great Seal during the month of October.

Specification of the Patent granted to FREDERICK BARTHOLOMEW FÖLSCH, of Oxford-strect, in the Parish of Saint James Westminster, in the County of Middlesex, Mer chant; for several Improvements on certain Machines, Instruments, and Pens, calculated to promote Facility in Writing. Dated May 9, 1809.

With a Plate.

To all to whom these presents shall come, &c. NOW KNOW YE, that in compliance with the said proviso, I the said Frederick Bartholomew Fölsch do hereby describe and ascertain the nature of my said invention and improvements in manner following; that is to say: First; in having a valve acting with a spiral spring, or a screw to affix on the tube of the pen, to supply it occasionally with air to force the ink into the socket of the pen. Secondly; in having a small pipe at the bottom of the tube to convey the ink into the socket of the pen through which it is forced by the operation of the valve VOL. XVI.-SECOND SERIES,

K

at

at the top of the tube. Thirdly; in having a plate on front of the socket of the pen to contain a supply of ink for the nib, and to prevent the ink flowing too freely into the nib.

The drawings or plan in the margin of these presents, and the following description thereof, with the marks of reference, will convey a more perfect knowledge of the separate parts, and in what manner the same is to be performed.

Figure A (see Plate IV.) is a section of a pen, which may be made of any sort of metal consisting of three parts, which may be joined together by screws or socket joints. No. 1 at the top I call the box, No. 2 the tube, and No. 3 the socket; it is made in three divisions, for the purpose of cleaning the pen in case it should get foul, and to supply the tube with ink, and to affix any of the different sockets to the tube at pleasure. The box No. 1 has a bottom soldered in, having a hole in it to admit air to pass into the tube through the top of the box; it contains a spiral spring: a small rod at a, having a plate or valve b at the bottom of it covered with leather, passes through the hole at the bottom of the box, but is not so thick as to fill the hole, and the rod a screws into the nob c, and confines the spring within the box: the spring pressing upwards against the nob c keeps the plate or valve b close to the bottom of the box, to prevent the ink getting out of the top. The tube No. 2 has a bottom soldered in at a, above the joint that unites it with the socket in the bottom is a small pipe or tube e, for the ink to pass through into the socket. The socket. No. 3 is hollow, and has a hole in the front, at ƒ, to admit the air, and to adjust the quantity of ink it will bear: the lower part or cradle g is made in the shape of a

common