|SELECT DISTINCT patent.*, YEAR(date) as year FROM patent LEFT JOIN category ON category.patent = patent.patent AND category.type = patent.type WHERE (category.class = '307') AND (category.subclass = '90') ORDER BY specimen DESC, date, patent, type|
Total of 1 patents found where: Class is '307'; Subclass is '90';
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|T / S||Patent||Date||Description||Patentee||Category||Assigned To|
|U||224,580||February 17, 1880||Induced Current Guard for Electrical Conductors
Pre-transposition technique to eliminate induced current on telephone and telegraph wires
|CHINNOCK, Charles E.
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