The measuring of compressed air, under high pressures, by means of observing the drop in pressure on passing thru an orifice, is in a new field of endeavor. The necessity of measuring compressed air, in order to handle it economically, is obvious. Hence, the importance of a simple device by which this may be done. A device, which may be duplicated at any time, at any place, with very little expense, and ordinary materials --Introduction, page iii
