Photo 15: YPCIC Milford 2008 Barclay Spiral Groove SDP

By Joe Maurath, Jr.; posted July 13, 2008
View Original: Click to zoom, then click to magnify (1200 x 1600) 373KB


Here is the rear view of the BARCLAY marked insulator with SDP and the familiar October 8, 1907 "spiral groove" patent date. Part of the club's show-n-tell at Milford.

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