boiler. Fig. 13, is a vertical section taken through the middle: a, and a*, are two circular chambers, or small cylinders formed of iron or other suitable materials, screwed into or otherwise securely fastened on to a base or footpiece b, b, through which a channel or passage c, c, is made for the purpose of forming a communication between the two cylinders; into the centre of the base a small tube or socket d, is screwed, for the purpose of supporting the glass tube e, and under this tube another channel g, g, is made communicating with the passage c; in the base the lower parts of all these vessels and passages are occupied with mercury up to the level marked m, m; near the top of the cylinder a, a cock f, is inserted, by which steam is to be admitted from the boiler or generator into the cylinder, when the pressure is desired to be ascertained. On the upper end of the other cylinder a*, there is a chamber h, with a cap screwed thereon, supporting a glass tube i, properly secured into the upper end of the chamber, and rendered perfectly air-tight; the top of the tube i, has a spherical air-chamber o. The chamber h, is furnished with a small valve k, for the admission of air into the chamber, and opposite to it there is a socket 1, which receives the upper end of the glass tube e: the chamber a, and a*, with the communicating passages, are charged with mercury, as said by removing the screw cap from the socket, and pouring the mercury into the glass tube e, which, by descending into the chamber a, and a*, will flow to about the level shown. There is a small tube or cylinder piece z, screwed into the foot-piece immediately under the chamber a, in order to conduct the mercury to the passage c, from the centre of the column, and thereby prevent the passage of any condensation of steam which might pass down the sides of the column. On the

admission of steam through the cock f, the mercury will be forced down in the chamber a, and rise up into the chamber h, and glass tube i, i, and there indicate the pressure of the steam within the boiler. The scale n, n, placed behind the tube, or the tube itself being graduated, will show the amount of pressure of the steam upon every square inch. The spherical air-vessel o, has a screw plug p, for the purpose of increasing or diminishing the capacity of the air-chambers, by means of which plug the volume of air to be compressed may be adjusted to the graduated scale. The valve k, is simply employed for the purpose of regulating the air contained in the spaces h, i, o, to the pressure of the external atmosphere, which is done by raising the plug, and thereby opening a small lateral air-channel g; and the equilibrium being thus effected, the plug is then screwed down again, previously to which the steam is to be cut off from the gauge, by closing the cock f. It will be seen by this arrangement the instrument is perfectly under command, for as often as it may be thought desirable to regulate the gauge, the air occupying the spaces may be adjusted to the proper or atmospheric density; and should it be found, on removing the pressure of the steam, that the mercury does not descend, or stand at its former level in the glass tube e, (previously marked), it will be perceived that the air within has varied in density, which may be corrected and adjusted to an equilibrium with the external atmosphere by opening the valve k. The glass tube i, is made conical, or tapering towards the top, for the purpose of diminishing its capacity, as shown in the drawing; by which arrangement the graduations on the scale may be made equal: whereas if the tube is cylindrical, the degrees must be decreasing in space towards the top, in proportion to the

increasing density of the air. It will be evident, when any other elastic vapour than atmospheric air is employed as the volume to be compressed in density by the pressure of the steam, that a reservoir of such gas or vapour must be connected to the valve or passage k, to adjust its density, and restore it to its proper equilibrium, as before described, with reference to atmospheric air.

In conclusion, the Patentee remarks, having now explained the nature of my invention, and the manner of carrying the same into effect, I wish it to be understood that I claim as the subject of my invention the peculiar construction and novel arrangement of the steam-gauge above described, and particularly the application of a volume of atmospheric air or other elastic vapour, under any modified variation, capable of being compressed into a smaller volume or greater density by the pressure or force of the steam, or other elastic vapour or gases, contained in the boiler or generator, for the purpose of ascertaining and indicating the pressure or force of such steam or vapour.-[Inrolled in the Rolls Chapel Office, 4th May, 1836.]

To JAMES LEEMING, of Manchester, in the coun'y of Lancaster, worsted spinner, for certain improvements in the construction of water-wheels and of paddle-wheels.[Sealed 9th February, 1835.]

THESE improvements in the construction of water-wheels and paddie-wheels, have for their object the regulating or governing the positions of the float-boards in such manner that the resistance of the back water may be diminished,

and thereby avoid the loss of power occasioned by such impediment.

Plate I., fig. 14, represents an elevation of one of these improved wheels: a, a, are the radial arms, which are, in this case, provided with a slot or goove extending from the centre outwards: in these grooves, the float-boards b, b, are mounted, being provided with small anti-friction rollers, to enable them to slide more. easily in approaching to, or receding from, the centre of the wheel c, c, is one of two scroll guides or excentric grooves, one of which is to be affixed to each of the sides of the vessel, or walls of the water-course. In the figure, the front one is removed, the better to expose the parts. In this groove, the axles of the float-boards work so, that in the revolution of the wheel they are brought nearer to, or propelled further from, the centre, according to the position of the scroll. By inspecting the figure, it will readily be perceived that as long as the float-boards are in an effective situation, they are propelled to their farthest extent from the centre; but directly they arrive at that point, where, by continuing in their primary position, they would be impeded by lifting the back water, they are withdrawn by the peculiar form of the scroll guide, and retreat from the water without impediment.

The above modification will readily serve for applying the same invention to the paddle-wheels of steam-boats, as no material alteration is necessary.

In conclusion, the Patentee remarks, "Although I have described various well-known parts of machinery in the foregoing specification, I do not claim any such wellknown parts separate and distinct as my invention; but I do claim the application of the scroll excentric, or any similar form of excentric to water-wheels and paddle-wheels,

for the purpose of receding or drawing the floats, paddles, or boards, towards the centre of such wheels, at such period of the revolution as may be found most desirable to lessen the amount of resistance on leaving the water; and such my invention being, to the best of my knowledge and belief, new, and never before used.-[Inrolled in the Inrolment Office, August, 1835.]

TO WILLIAM WESTLEY RICHARDS, of Birmingham, in the county of Warwick, gun-maker, for his invention of certain improvements in primers for discharging firearms by means of percussion.-[Sealed 22nd March, 1836.]

THIS invention of certain improvements in primers for discharging fire-arms by means of percussion, applies to that kind or description of percussion primers commonly called copper caps, or those in which the detonating powder or priming is contained in a copper cap or metal shell or case, and have for their object the transferring or removal of the explosion or discharge of the percussion or detonating powder, whereby the necessity of deep projecting rims or shields round the cavity of the cock is obviated, as no part of the metal cap, case, or shell of these improved primers can be projected from the nipple in firing, and the liability of the head of the cock being broken by the explosion of the priming (which frequently happens with the common copper cap) is also obviated. And another object of these improvements is the making of the primers much larger than the ordinary copper caps, so as to be more readily handled, and easily affixed to the piece; at the same time they are equally impervious to wet,