Fig. 36.—Showing whole piece of thread.
A Trick in the Sunshine
This trick can only be done on a sunny day, for a reason which will be very evident to those who try it.
Obtain a clear glass bottle, in the cork of which stick a hooked pin. By means of a piece of thread hang a small weight from this pin within the bottle, as in [Fig. 37], and then request some one to cut the cord without drawing the cork.
Fig. 37.—Sun’s rays focused on weighted thread.
All that is necessary to do this is a magnifying glass which is placed between the bottle and the sun at the right distance to focus the rays of the latter upon the cord. In a few seconds the heat of the converging rays will burn through the thread, and the weight will fall to the bottom of the bottle. In the same way you can
Light a Cigarette Without Matches
Concentrate the rays of the sun upon the end of the cigarette, and draw in the ordinary way (if you are old enough to smoke), when the cigarette will rapidly be ignited.