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SCIENCE, MECHANICS, INVENTION 201
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A Folding Dark Room
A clever contrivance has
been patented which will
permit an amateur photographer
to change plates
or develop exposed plates
without using a dark room.
The device is constructed
in the shape of a large
square. The sides fold up
and the top and bottom
sections ari; light-tight
trays which fit over the
sides when ready for use.
An opening in front of the
box containsasheet of ruby
glass which allows the entrance
of enough light to
discern all necessary movements.
A curtain on the
inside of the box regulates
the light passing through
the ruby glass. A peep bole
is pined on the top section
of the box toward the rear
and is protected by an eye
shade which is hinged so as
to allow its being folded up
tl.it mi the top of the box.
PICTURING THE VOICES OF OPERA STARS
Delegates to the Congress of Scientists saw the voices of Caruso, Tetrazzini, and A mato dance before
their eve-, on the wall of a darkened room. The phonodeik—the device is shown above—consists of a
supersensitive diaphragm of a gauze-like material, through which the soun I waves pass, causing vibration.
A series oi highly polished mirrors reflects the vibrations to a revolving triangular mirror disc.
which in turn reflects them upon a screen. The sound wave reflections appear upon the screen magnified
40,000 times the size of the vibrations upon the diaphragm. Caruso's voice is pictured through
the phon deik. varied from a clearly outlined curved line to a shadowy blue as his voice rises from a
low, natural note to a high burst of volume. The voice of Tetrazzini was as different from Caruso's as
d,iv from night, The voices of four opera stars are charted on the wall back of the machine*.
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