The more batteries used the louder will be the sound produced by
the horn, but avoid using too much battery or the receiver is apt
to heat.
--Contributed by Wm. J. Farley, Jr., Camden, N. J.
** How to Make a Telescope [108]
With a telescope like the one here described, made with his own
hands, a farmer boy not many years ago discovered a comet which
had escaped the watchful eyes of many astronomers.
First, get two pieces of plate glass, 6 in. square and 1 in.
thick, and break the corners off to make them round, grinding the
rough edges on a grindstone. Use a barrel to work on, and
[Illustration: Homemade Telescope]
fasten one glass on the top of it in the center by driving three
small nails at the sides to hold it in place. Fasten, with pitch,
a round 4-in. block of wood in the center on one side of the other
glass to serve as a handle.
Use wet grain emery for coarse grinding. Take a pinch and spread
it evenly on the glass which is on the barrel, then take the glass
with the handle and move it back and forth across the lower glass,
while walking around the barrel; also rotate the glass, which is
necessary to make it grind evenly.
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