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 Past-board, 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.

I have made several trials and Instruments for discovering the driness and moisture of the Air with this little wreath’d body, and find it to vary exceeding sensibly with the least change in the constitution of the Air, as to driness and moisture, so that with one breathing upon it, I have made it untwist a whole bout, and the Index or Hand has shew’d or pointed to various divisions on the upper Face or Ring of the Instrument, according as it was carried neerer and neerer to the fire, or as the heat of the Sun increased upon it.