Materials Required:—

A large button or small round of leather or thin tin, a piece of strong thin string, strong scissors.

This can be simply made by threading a large button on a string, so that when the ends are knotted together it makes a loop about twelve to fifteen inches long. Keeping the button in the middle of the doubled length of string insert the first and second fingers of each hand into the looped ends, and rapidly whirl the button round till the string gets a considerable twist on it. Now by alternately slacking and tightening the string the button will whizz round with a slight humming noise. If a piece of tin with notched edges (as in Figure 51 of a windmill) is used, it will hum very loud. A piece of heavy lead foil, or a piece of firm leather cut into a round and notched at the edge can be used.