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@mwichary patentimages.storage.googleapis.com/52/b6/f6/bcbcf6583f950c/US2583184.pdf patentimages.storage.googleapis.com/1f/47/41/7147a728778cd4/US3968583.pdf (Arabic) patentimages.storage.googleapis.com/b5/af/ef/f9188470bbcbf5/US1091335.pdf (1912) patentimages.storage.googleapis.com/bd/cc/cd/f208e92cf4860b/US3938140.pdf (1976) patentimages.storage.googleapis.com/1b/c5/d8/ecf302290cf758/US3945001.pdf (1976, 7 segments, but curved)Permalink On twitter.com
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@mwichary patentimages.storage.googleapis.com/fb/86/68/f4547871966623/US3566391.pdf 1971 - ...many segments.On twitter.com
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@mwichary patentimages.storage.googleapis.com/61/1a/2d/8d8967d1c3410b/US2958009.pdf - 1959 - so far the earliest 'modern' 7 segment I can find.Permalink On twitter.com