Worthen, William Ezra, 1819-1897, [from old catalog] ed · New York, Appleton · leaf 389
Fig. 851. Fig. 853. feathers are straight, and often four instead of three. Fig. 850 is a poppet-valveguided by a central stem ; both these valves have conical faces and seats, withgenerally an inclination of 45° to the axis of the valve. In many valves thefaces and seats are flat, one or the other…
Mechanical drawing
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