groove, which meets the edge of metal in the middle of the vanes kk, Fig. 3. FF, is the main axle of the machine, laid in its place without the vanes; one end of which is to perform the necessary work required, and the other is applied to the discharging-pump. At DD the packing extends to WW, so as to embrace the nave as well as the descending vane, by which means both the nave. and the vanes move steain-tight in their revolutions, vvvv is that part of the partition which forms a plane at the axis of the globe, and is secured in its place by being seated in a rabbet with the usual jointing materials on the interior margin of the steam vessel. G G are two brasses let down into the partition, and they are raised or depressed with screws, as adjustment may require. Attt spaces are left for packing round the axle; and the upper brasses which keep down the axle serve also to keep it in its place. At HH are the stuffing-boxes, mer tioned in Fig. 1; they have a division-plate of metal in them, so that SS being supplied with steam from the valve-box, the packing of each side of these vacuities are rendered air tight. The manner in which the partition and vane-ports are constructed, is by rivetting the two parts v together by means of flanches at II, first having mounted them on an axis, to correct, by turning, (either by hand or otherwise,) the want of smoothness and truth from the casting; and when this is done the main axle is fixed to its place as a guide by which to set up the four vanes, as at Fig. 3, where, by a mere inspection, it is plain how this is performed. The open yane exhibits a frame of metal, which receives a plate on each side these plates, with the edge of metal K K, cast with the frame, form grooves and vacuities to receive the packing, The naye being hollow, receives two iron

axles, which are curved in the middle, and there cross each other. The manner in which they receive the vanes is shewn by the figure; also how the packing renders them steam-tight on the spherical part of the nave, and that when one of them is moved its opposite vage on the same axle must likewise be moved. The main axle is turned true by rivetting the two parts together at the nave, and re-rivetting them after the cross axles are set in their places. All the several parts of the machine being then put in their respective situations, it is very evident that when steam is admitted into the lower apartment the rising vane, which occupies the largest passage, must overpower the other in its descent; and that if by any means one of the vanes be turned a quarter of a revolu tion, it must at the same time carry with it the onc which is connected on the opposite side of the nave; and this turning is effected by fixing with screws a block of wood on the partition at KK, in the form of a strong bracket. This block will not permit the ascending vane to pass it without being turned on its edge, by which means the one below is turned at the same time, to present its broad surface to the large vane port. It may be necessary to remark, that when the machine is to be set at work, the steam is not admitted into the upper apartment of the vessel, to exclude the air, but enters immediately from the valve-box to the eduction or discharging pipe, in order to preserve the grease which is made use of to lubricate the internal moveable mechanism of the engine.

For the farther explanation of the manner in which I prepare the packing for the necessary parts of the machine, I farther remark, that I arrange strands of ropeyarn by a method somewhat similar to that adopted in making fringe. A sufficient number of fringes are laid

at

Fig. 4.

at the side of each other for filling the grooves or spaces they are to occupy; and then they are sewed slightly to-. gether. After this they are, for the vanes, placed edge-, wise on a flat iron collar, jointed at its corners, and then lashed firmly thereto by means of rope-yarn passing through the body, of this fringed fabric, and wrapping round the iron collar, so that when the collars of hemp and iron are in their respective places, the end of the fibre of the hemp is presented to the abrading parts; and by means of a small pin, driven through the thickness of the vane at SS, Fig. 3, the whole are immoveably retained in their proper situations. I also adopt the same kind of fabric for the side packing at DD, Fig. 2, but I here fasten the hempen fringes to pieces of wood instead of iron, and present the ends of their fibre to the sides of the descending vane. At other places where this kind of packing is not eligible, nor so much required, I adopt the common method of packing. As it is not eligible any more than absolutely necessary, to pack the vanes whilst they are situated in the large vane port, they are by cutting or shearing successively made to enter it, and receive their proper configuration. Where circumstances will admit, I adopt the use of angular teeth, in the form of a cheveron, for the purpose of connecting and turning any wheel-work that may be an appendage to the machine, by which means I obtain all the advantages resulting from small teeth, in respect to what artists call their taking and leaving, without the liability of their being so soon broken, or otherwise affected, from the diminutiveness of their size.

Fig. 4 shews an eligible proportion for such angular, teeth, their depth being equal to the part of the tooth at, S in the direction of the dotted line. In order to make my machine appropriate to the draining of mines, &c. I

adopt