A Simple Balance
Having use for a balance in a laboratory and being unable to procure any scales at the time, I hastily rigged up a device that served the purpose as well, as the work did not require very great precision. An elastic band and a short piece of string was procured and the band cut open. The string was then fastened around the beaker as shown, and the whole suspended from a shelf.
A Graduate Scale Used in Connection with an Elastic Band to Make a Simple Balance
Into the beaker was then poured 100 cubic centimeters of water and the stretch of the elastic band noted by the displacement of a knot in the string in respect to the scale on a graduate, placed beside the beaker. The length of the elastic was then changed until the knot was exactly opposite the 100-division mark on the graduate scale. Then, since the elongation of the elastic band follows Hook's law, the extension of the band to the amount of one scale division means an added weight of one gram in the beaker.—Contributed by L. Horle, Newark, New Jersey.
An Ink Eraser
A good knife eraser for ink can be made from a discarded or broken ruling pen. One of the parts, or nibs, is cut off close to the handle and the remaining one sharpened on both edges at the point. This instrument is better than a knife or the regular scratcher, because the cutting edge will shave the surface of the paper or tracing cloth and not roughen or cut it. Erasing done with this knife will readily take ink without further preparation of the surface.—Contributed by Warren E. Crane, Cleveland, O.
One of the Nibs on the Ruling Pen Sharpened and Used as an Eraser