ormation herewith presented we have drawn might, at trifling cost, procure a cool and pure atmos- received by a parabolic reflector, in the focus of which on an excellent paper on selenium prepared by Mr. is placed a selenium cell connected with a battery and phere for himself. Considering that… … THE RECEIVING INSTRUMENT. upon the carbon caused variations of temperature inside of the glass bulb, ature of —191 deg. C., it is hardly a matter of surprise two of the photographs herewith reproduced. which produced the original sounds in the listener’s that, with such an energetic cooling medium…
Internet Archive · Public domain (published before 1931). Free to use for anything.
