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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 = '137') AND (category.subclass = '512.1') ORDER BY date ASC, patent, type

Total of 1 patents found where: Class is '137'; Subclass is '512.1';

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T / S Patent Date Description Patentee Category Assigned To
 1872
U Specimen known 123,878 February 20, 1872 Improvement in Telegraph Insulators
CD 141.9, four projections to reduce surface contact 		EMMINGER, David R. P.
 Insulator  

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