Worthen, William Ezra, 1819-1897, [from old catalog] ed · New York, Appleton · leaf 390
ubber, on a suitable grating, with a curved guard attached on one side. For the common air-pump pressure, f rubber is sufficient for apertures 1 X 4. With the use of backing and face plates on the rubber or leather flaps, gratings may be dispensed with (Fig. 859). Valves of this… … 374: MACHINE DESIGN AND MECHANICAL CONSTRUCTIONS.
Mechanical drawing
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