There may be multitudes of other ways for contriving this small Instrument, so as to produce this effect, which any one may, according to his peculiar use, and the exigency of his present occasion, easily enough contrive and take, on which I shall not therefore insist. The whole manner of making any one of them is thus: Having your Box or frame AABB, fitly adapted for the free passage of the Air through it, in the midst of the bottom BBB, you must have a very small hole C, into which the lower end of the Beard is to be fix’d, the upper end of which Beard ab, is to pass through a small hole of a Plate, or top AA, if you make use onely of a single one, and on the top of it e, is to be fix’d a small and very light _Index_ fg, made of a very thin sliver of a Reed or Cane; but if you make use of two or more Beards, they must be fix’d and bound together, either with a very fine piece of Silk, or with a very small touch of hard Wax, or Glew, which is better, and the _Index_ fg, is to be fix’d on the top of the second, third, or fourth in the same manner as on the single one. Now, because that in every of these contrivances, the _Index_ fg, will with some temperatures of Air, move two, three, or more times round, which without some other contrivance then this, will be difficult to distinguish, therefore I thought of this Expedient: The _Index_ or _Hand_ fg, being rais’d a pretty way above the surface of the Plate AA, fix in at a little distance from the middle of it a small Pin h, so as almost to touch the surface of the Plate AA, and then in any convenient place of the surface of the Plate, fix a small Pin, on which put on a small piece of Paper, or thin Pastboard, Vellom, or Parchment, made of a convenient cize, and shap’d in the manner of that in the Figure express’d by ik, so that having a convenient number of teeth every turn or return of the Pin h, may move this small indented Circle, a tooth forward or backwards, by which means the teeth of the Circle, being mark’d, it will be thereby very easie to know certainly, how much variation any change of weather will make upon the small wreath’d body. In the making of this Secundary Circle of Vellom, or the like, great care is to be had, that it be made exceeding light, and to move very easily, for otherwise a small variation will spoil the whole operation. The Box may be made of Brass, Silver, Iron, or any other substance, if care be taken to make it open enough, to let the Air have a sufficiently free access to the Beard. The _Index_ also may be various ways contrived, so as to shew both the number of the revolutions it makes, and the _Minute_ divisions of each revolution.