** Home-Made X-Ray Instrument [151]
Two cylinders, AA, are mounted on a base, B, and mirrors, CC, are
fitted at an angle of 45 deg. into these cylinders. Corresponding
mirrors, EE, are put in the base parallel with those in those
cylinders. An opening extends downward from D of each cylinder so
that light entering at one end of the
[Illustration: Details of X-Ray Machine]
cylinder is reflected down at right angles by the first mirror to
the second, from the second to the third, from the third to the
fourth which reflects the light to the eye. Thus the light never
passes through the cylinders and the observer does not see
through, but around any object inserted at X between the
cylinders.
** How to Make a a Non-Polarizing Battery [151]
Bichromate batteries are very expensive to maintain and dry cells
do not furnish enough amperage for some kinds of experimental
work. A cell of a battery that will run 10 hours with an output of
over 1 ampere can be made as follows: Secure a jar about 4 in. in
diameter and 8 in. high and place in the bottom of this jar the
lower half of a tin baking powder can, to which a wire has been
soldered for connections.
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