ther things in order to make the arm operate. At least it is
amusing. Try it and see.
--Contributed by Charles Clement Bradley Toledo, Ohio.

** Effects of Radium [116]

Radium acts upon the chemical constituents of glass, porcelain and
paper, imparting to them a violet tinge; changes white phosphorus
to yellow, oxygen to ozone, affects photograph plates and produces
many other curious chemical changes.

** Naval Speed Record [116]

On its official trial trip the British torpedo boat destroyer
"Mohawk" attained the record speed of a little over 39 miles an
hour.

** How to Enlarge from Life in the Camera [117]

Usually the amateur photographer gets to a point in his work where
the miscellaneous taking of everything in sight is somewhat
unsatisfying: There are many special fields he may enter, and one
of them is photomicrography. It is usually understood that this
branch of photography means an expensive apparatus. If the worker
is not after too high a magnification, however, there is a very
simple and effective means of making photomicrographs which
requires no additional apparatus that cannot be easily and quickly
constructed at home.

Reproduced with this article is a photograph of dandelion seeds --
a magnification of nine diameters or eighty-one times. The
apparatus which produced this photograph consisted of a camera of
fairly long draw, a means for holding it vertical, a short-focus
lens, and, if possible, but not essential, a means for focusing
that lens in a minute manner. On top of the tripod is the folding
arrangement, which is easily constructed at home with two hinged
boards, an old tripod screw, an old bed plate from a camera for
the screw to fit in, and two sliding brass pieces with sets crews
that may be purchased from any hardware store under the name of
desk sliding braces. To the front board is attached a box,
carrying the lens and the bed of the sliding object carrier, which
can be moved forward and back by the rack and pinion, that also
can be obtained from hardware stores. If the bed for the object
carrier be attached to the bed of the camera instead of to the
front board, the object carrier need have no independent movement
of its own, focusing being done by the front and

[Illustration: Enlargement with a Camera]

back focus of the camera; but this is less satisfactory,
particularly when accurate dimensions are to be determined, says
the Photographic Times. This outfit ne