The Moon-element: An Introduction to the Wonders of SeleniumT.F. Unwin, 1924 - 166 pages |
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Common terms and phrases
action of light apparatus audible Author Barr and Stroud beam of light Birmingham University BLACK-SOUNDING blind person Braille coil colour conductivity conductor constructed copper crystalline dark disc discover discovery dots E. E. FOURNIER D'ALBE effect electric current EXPLORING OPTOPHONE film free electrons galvanometer glass plate graphite illumination inch instrument invention inventor ionisation lamp lens letters luminous magnets matter micro-ampère milliampère mirror Miss Jameson molecules Moon type musical National Institute Nernst lamp notes number of ions obtained optical orbits phonofilm phonoptikon photion photophone picture practice printed produced properties of selenium protons read by ear reading optophone recombination Reginald Bacon relay resistance revolving Ruhmer searchlight selenium atoms selenium bridge selenium cell selenium tablet sensitive Sir Arthur Pearson slate speed sulphur surface telephone receiver telescope tellurium tion transmitted TYPE-READING OPTOPHONE vibrations waves Wheatstone bridge wire wireless words in thirty words per minute
Popular passages
Page 34 - Being desirous of obtaining a more suitable high resistance for use at the Shore Station in connection with my system of testing and signalling during the submersion of long submarine cables, I was induced to experiment with bars of selenium, a known metal of very high resistance. I obtained several bars varying in length from 5 to 10 centimeters, and of a diameter from 1 to 1$ millimeters.
Page 34 - ... was subjected. When the bars were fixed in a box with a sliding cover, so as to exclude all light, their resistance was at its highest, and remained very constant, fulfilling all the conditions necessary to my requirements ; but immediately the cover of the box was removed, the conductivity increased from 1 5 to 100 per cent, according to the intensity of the light falling on the bar.
Page 17 - Kelvin has shown that if a drop of water were magnified to the size of the earth the molecules of water would be of a size intermediate between that of a cricket ball and of a marble.
Page 35 - If the light be intercepted by glass of various colours, the resistance varies according to the amount of light passing through the glass. To ensure that temperature was in no way affecting the experiments, one of the bars was placed in a trough of water so that there was about an inch of water for the light to pass through, but the results were the same ; and when a strong light from the ignition of a narrow band of magnesium was held about nine inches above the water the resistance immediately...
Page 71 - ... affairs, the chancellor of the exchequer, and the first lord of the admiralty; with Admiral Fisher, General Wolfe Murray, the CIGS, and the inevitable Balfour, and Hankey as secretary.
Page 35 - ... intensity of the light falling on the bar. ... To ensure that temperature was in no way affecting the experiments, one of the bars was placed in a trough of water so that there was about an inch of water for the light to pass through, but the results were the same; and when a narrow band of magnesium was held about nine inches above the water the resistance immediately fell more than twothirds, returning to its normal condition immediately the light was extinguished.
Page 34 - While investigating the cause of such great differences in the resistance of the bars, it was found that the resistance altered materially according to the intensity of light to which they were subjected. When the bars were fixed in a box with a sliding cover, so as to exclude all light, their resistance was at its highest, and remained very constant...
Page 34 - I to ij millimetres. Each bar was hermetically sealed in a glass tube, and a platinum wire projected from each end for the purpose of connection. The early experiments did not place the selenium in a very favourable light for the purpose required, for although the resistance was all that could be desired — some of the bars giving 1,400 megs, absolute — yet there was a great discrepancy in the tests, and seldom did different operators obtain the same result. While investigating the cause of such...
Page 35 - ... fulfilling all the conditions necessary to my requirements; but immediately the cover of the box was removed, the conductivity increased from 15 to 100 per cent, according to the intensity of the light falling on the bar. Merely intercepting the light by passing the hand before an ordinary gas-burner, placed several feet from the bar, increased the resistance from 15 to 20 per cent.
Page 34 - Each bar was hermetically sealed in a glass tube, and a platinum wire projected from each end for the purpose of connection. "The early experiments did not place the selenium in a very favorable light for the purpose required; for although the resistance was all that could be desired — some of the bars giving 1,400 meg,ohms absolute — yet there was a great discrepancy in the tests, and seldom did different operators obtain the same results. While investigating the cause of so...