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6"circle read bytwoopposite verniersto 1 min.of an arc.Completein wooden box.
6" circle read by twoopposite verniersto 30 second of an arc. Complete in wooden box.
7"circle read by two opposite verniers to one minuteof an arc Complete in wooden box
10"c ircle read by two opposite verniers to 30 sec. of an arc. Complete in wooden box