BEFORE the introduction of the modern form of hand micro-telephone instrument and before thermionic amplifiers were introduced on trunk telephone lines, the extra receiver was considered a useful ...
As I noted last week, the term “wireless telephone” in the early 1920s didn’t necessarily mean a device that could both transmit and receive messages. In fact, most radio devices during this time were ...
IIIF provides researchers rich metadata and media viewing options for comparison of works across cultural heritage collections. Visit the IIIF page to learn more. overall: 2 1/4 in x 9 in x 4 in; ...
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