IN a communication, dated October 17, from the Smithsonian Institution, Washington, an account is given of experiments made by Dr. Charles G. Abbot, secretary of the Institution and Mr. W. H. Hoover, ...
THE three-electrode valve offers a very simple and trustworthy method of amplifying the small currents produced in the thermopile of an infra-red spectrometer. Bright lines are more readily picked up ...
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