In [Plate 17], [figs. 7 and 8], offer a mechanism different from the preceding, though intended to produce a similar effect. Referring to that cause of friction which consists in the want of parallelism between a principal shaft and its friction rollers, I here introduce a form for the latter, which admits of this consideration being in a measure neglected. These friction rollers are only portions of cylinders; and they have no shafts. They turn simply on a sharp edge, placed in a prismatic box A B, in a well formed angle of which, they move to and fro, without rubbing. When at rest, these axes D C D, ([fig. 7 and 8]) are drawn against the right hand side of the box, by small weights E; and the shaft is carried by one or the other of them, according as they are, or are not, within reach of its radius. Thus, in the present position of the shaft, (see [fig. 7]) the second arc C supports it, the third having fallen behind the first, so as not to be seen: and the first arc D being on the point of taking up the load. In short there are six spaces, either left or cut on the shaft, opposite the three arcs D C D. 1st. one space, of 1⁄3 of the circumference, left concentric with the real centre of the shaft, opposite the first arc D, followed by 2⁄3 of a circumference cut an eighth of an inch lower. 2ndly. another third of a circumference opposite the second arc C, beginning where the first ends, and followed by 2⁄3 of a circumference cut an eighth of an inch lower: and 3rdly, another space of 1⁄3 in circumference, opposite the arc D, followed by a similar space of 2⁄3 cut an eighth of an inch lower. By these means the shaft is never without a concentric bearing: and the better to secure this property these arcs left, may be each of them more than one third of a circumference in length, so as to avoid the least drop at each change of roller; and even to give the shaft a support from two rollers at once, during a good part of its revolution.
In using this mechanism, the vessel A B, would be filled, to a certain level, with oil or water, to prevent any blow from the returning arcs—which latter might be made to fall on a lining of leather, to avoid still further all commotion: and thus, even were these rollers not placed quite parallel to the shaft, this imperfection would be corrected by the frequent renewal of these movements, and the consequent absence of lateral friction between the arcs and the shaft. It may be observed that either of the above methods of destroying friction is not confined to the vertical direction: but may be so used as to receive the pressure caused, in any direction, by the action of a wheel or other agent. And with respect to the best use of each method respectively, I would propose the former for light and swift motions, and the latter for slow-going shafts, heavily laden: it being well understood that the shafts must be kept in their places, in the less essential directions, by proper steps, at the discretion of the person who employs these Machines.
Finally, I consider it as a matter of course, that all the surfaces coming into contact in these operations, should be as hard and impenetrable as possible. For if, by neglecting this precaution, any change of form occurred, what is said above could not be practically true: But these properties can be realized, with only those degrees of hardness that are often employed in the mechanical world. Thus a die of hardened steel, bears almost unimpaired, the strokes and pressure it suffers in the coining-press. A chisel, stands thousands of blows and cuts hard metal, without sensibly giving way. The knife-edges which carry a heavy pendulum, suffer it to vibrate many years without wearing out; and the fulcrums of scale-beams, bear enormous weights, for almost an indefinite period, without any injurious effect. I request therefore, that these facts, may be put into the scale, when my foregoing statements are tried: whether as applied to these anti-attrition machines, or to my late patent wheel work, or both combined: for I foresee the use of these friction rollers, cut into teeth on that principle, to insure the proportionality of their respective motions.
OF
AN EQUILIBRIUM COCK,
To prevent abrasion and leakage.
In the common form of this useful instrument, no method seems to have been devised for preventing the plug from being pressed aside, by the weight of the liquid: which provision nevertheless would have diminished the wear and tear of the touching surfaces, and secured much longer the perfection of the instrument. This property would be particularly desirable in cocks which convey a fluid from a great height; and still more so in those used for containing steam or any other fluid under a high pressure. I can hardly persuade myself that I have stood so long alone in my ideas upon this subject; but not having seen any thing published on the subject, under a name implying the above mentioned property, I venture to give this as my invention—which indeed it is, even should other persons have pursued and embodied the same idea.