awn 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 liauefled air, va- William J. Hammer, to… … THE RECEIVING INSTRUMENT. upon the carbon caused variations of ARRANGEMENT FOR SPEAKING IN TWO DIRECTIONS 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…
Patents · Motor · Apparatus · Automobile · Piston · Horse power · Castor frame · Sewing machine · Scientific American · Average speed · York city · Tractive effort · Gordon bennett · Swage block · Selenium cell
Internet Archive · Public domain (published before 1931). Free to use for anything.
