[Trade Journal]
Publication: Electrical World
New York, NY, United States
vol. XVI, no. 10, p. 177, col. 2
OUR ILLUSTRATED RECORD OF ELECTRICAL PATENTS.
U. S. Patents Issued August 19, 1890.
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434,879. Electric Insulator; Samuel Oakman, of Melrose, Mass. Application filed Sept. 13, 1889. In an insulator, the combination of the petticoat and a series of internal annular projections having inclined tops and flat bases adopted to act as waterstops.
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