Lectures de Potentia Restitutiva, or of Spring

If one ounce, or one pound, or one certain weight lengthens a spring by one line A "line" was a traditional unit of measurement equal to 1/12 of an inch., or one inch, or one certain length, then two ounces, two pounds, or two weights will extend it two lines, two inches, or two lengths; and three ounces, pounds, or weights will extend it three lines, inches, or lengths; and so forward. And this is the Rule or Law of Nature This is the first formal description of what is now known as Hooke's Law: F = kx. upon which all manner of restorative original: "Restituent" or springing motion proceeds, whether it be by thinning original: "Rarefaction", or extension, or thickening original: "Condensation" and compression.

Or, take a watch spring and coil it into a spiral so that no part of it touches another. Then, provide a very light wheel made of brass or a similar material, and fix it on an axle original: "arbor" that has two small steel pivots. Turn the edge of the wheel upon these pivots until it is very even and smooth, so that a small silk thread may be coiled upon it. Then, put this wheel into a frame so that the wheel may move very freely on its pivots. Fasten the inner end of the spring close to the pivot hole or center of the frame where the axle of the wheel moves, and the other end of the spring to the rim of the wheel.

Next, by coiling a fine, flexible original: "limber" thread of silk upon the edge of the wheel, hang a small light scale at the end of it, suitable for holding the weights that will be placed in it. Then, allowing the wheel to stand in its natural position, use a little pointer original: "index" fastened to the frame and pointing to the rim of the wheel to make a mark with ink (or something similar) on the part of the rim the pointer indicates.

Then, put a dram original: "drachm"; a unit of weight equal to 1/8 of an ounce. weight into the scale and allow the wheel to settle, and make another mark on the rim where the pointer indicates. Then add a second dram and let the wheel settle again, noting with ink, as before, the place on the rim pointed to by the pointer. Then add a third dram and do as before, and so a fourth, fifth, sixth, seventh, eighth, etc., allowing the wheel to settle and marking the several places pointed to by the pointer. Then examine the