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US1407726A
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Thermophone and method of making it
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Thermophone
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Method of making thermophone elements
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Transmitter
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US1338888A
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Method of making thermophones
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US1338886A
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Machine for making thermophone-blanks
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US1338887A
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Machine for finishing thermophones
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Thermotelephone transmitter and receiver
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Thermic telephone
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Thermic telephone
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US1328620A
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Sounding-chamber for thermic telephones and other apparatus
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US1366567A
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Earpiece for thermic telephones
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