Sucks books

Now, Walter, since you have become
accustomed to this thing take it and tell me what you hear."
Craig had already seized the other apparatus connected with the
art-gallery and had the wireless receiver over his head. He was
listening with rapt attention, talking while he waited.
"This is an apparatus," he was saying, "that was devised by Dr.
Fournier d'Albe, lecturer on physics at Birmingham University, to
aid the blind. It is known as the optophone. What I am literally
doing now is to HEAR light. The optophone translates light into
sound by means of that wonderful little element, selenium, which
in darkness is a poor conductor of electricity, but in light is a
good conductor. This property is used in the optophone in
transmitting an electric current which is interrupted by a special
clockwork interrupter. It makes light and darkness audible in the
telephone. This thing over my head is like a wireless telephone
receiver, capable of detecting a current of even a quarter of a
microampere."
We were all waiting expectantly for Craig to speak.


Pages:
145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169