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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 date ASC, 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
 1880
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.
 Transposition  

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