Take a piece of elastic which is not covered with silk or wool, and
through the middle of this stick a pin, which you have bent as shown
in the illustration.
Now hold the elastic between the thumb and first finger of each hand
and twirl it round, stretching it a little at the same time. The rapid
movement thus caused will make the revolving pin look like a glass
object, and if you have a strong light falling on the pin and a dark
background behind it, the resemblance becomes very much stronger.
After a little practice you will be able to represent many things in
this way--cheese dishes, vases, champagne glasses, etc.; and if the
bent pin should fall into a horizontal position while revolving, on
account of its shape, you can tie one end to the elastic with a piece
of white thread, which will not in any way interfere with the working.
This trick looks well in a darkened room, when the pin is illuminated
by a ray of sunlight coming through a hole in the window shutter.
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