I believe there is no better floor for a working horse to tread on, than a plane of wood—on condition, of the horse being rough shod: I speak however, on recollection of many years’ standing. I then felt persuaded that a horse wastes less effort by travelling on this floor than on any other; which is one of my reasons for the adoption of the present Machine. It consists ([Plate 26], [fig. 1],) of a wheel A B, on which the horse walks, as indicated by the sketch of him given in the figure. Besides this, he is placed between two shafts C D, affixed to the lever E F, the latter carrying round with it, at intervals, the drum G, whose office it is to raise the weight I, whatever kind of resistance that weight represents. This lever runs by means of it’s cannon L, on a round part of the shaft common to it and to the drum G. Moreover, there is a second drum H, destined to raise the weight K, whatever kind of resistance that represents. Both the drums, G and H, turn on round parts of the main shaft M, but are alternately connected with it—first, the drum G, by the rising of the bolt a into it; and secondly, the drum H, by the falling of the cross piece b c, between the studs e d affixed to it. Now, this cross piece b c, is part of a T-formed bar, that penetrates the centre of the shaft as low as f, where it rests on a transverse lever f g, connected to the right with the bolt a above mentioned, and forming a branch of the bent lever f g h, which works the bolt h i under the wheel. In the present state of things, if the horse steps forward, he draws the shafts C D, round the common centre; for the wheel is immoveable by means of the bolt i, which takes against some fixed object at k: and thus will the weight I be raised. And when this motion is achieved, the handle o is raised a few inches, which brings it into contact with the obstacle p, and puts a stop to that motion of the lever E F. At the same time the bolt a, is drawn out of the drum G, and the cross piece b c is let down between the studs of the drum H, while, by the bent lever f g h, the bolt h i, which held the wheel, is drawn back, and then the horse, instead of progressing round the centre of the wheel, is himself brought locally, to a stand; and without even knowing it, (for he is blinded) he now treads round the wheel in a backward direction, and raises the weight K, while the drum G permits the weight I to descend by the uncoiling of the rope, till this operation has likewise produced the desired effect—when things are again placed in the state first observed. One thing remains to be noticed: It is, that both these motions might have been produced by acting from a fixed point on the central bar b c f, through the upper gudgeon of the shaft, instead of using the handle o, as before directed. It is even easy to conceive how the Machine may itself be made to perform these changes, and thus to produce the whole effect without any personal care or attendance.
OF
AN EXPANDING VESSEL,
For Steam Engines, Pumps, Blowing Machines, &c.
It is one of the simplest and most perfect operations of the mechanic art, to form a flat surface: witness the process of grinding looking glasses, and forming one plane from another. Nor is it, necessarily, more difficult to place two surfaces parallel to each other, by means of three or more pillars with proper shoulders, or counternuts against which to screw the plates from behind. It is therefore easy to compose an expanding and contracting vessel, that shall become a mover by the force of any fluid, elastic or not, or shall act as a water or air pump, when driven by a convenient power; or both together, when this combination may be desirable. Thus, in [Plate 26], [fig. 2 and 3], A B C D is a box with four sides and four jointed angles—which, if one of it’s sides, D A, be fixed to a given position in the cage or frame E F G H, will expand or contract according as the sides A B and D C shall rise toward the perpendicular, or fall toward the horizontal position. The dotted lines A 2, A 4, A 6, &c. shew that the successive capacities included in the vessel, are respectively as the sines of the angles which those sides A B and D C make with the horizon; so that, although this device furnishes an unequable power, yet it is equable enough for many purposes in the first few divisions D 3, D 5, &c. and might be altogether equalized in it’s effect if necessary. Let us suppose then, that the aperture 8, brings steam into this vessel: The lid B C will rise to 6, 7, when, if the pipe 9, communicating with a condenser, be opened, the steam in the vessel will rush thither and be destroyed: when the atmosphere will press on the lid B C, and cause the vessel to collapse with a power proportionate to that area; for the sloping and parallel sides A B and C D counterpoise each other; where note, on occasion of the pressure which I am now speaking of, that the ribs or bars L M, are used to strengthen the sides of the vessel, and thus prevent it’s fracture under this pressure.
From this manner of making these expanding vessels, it follows among other things, that if the frame E F G H were surrounded with wood or any non-conducting substance, and made to communicate with a warm close room, the atmosphere thus acting on the vessel would not cool it, and that therefore, an atmospheric engine, would, in this respect, be as good as a steam-acting one. But steam might be introduced into this outer case, and act as a spring to reciprocate the internal effect of the same agent.