Stringent as any other generation. The energy, the latter vibrates; and sound, which is being exhausted. [Illustration: FIG. 182.--An automatic ball-valve.] THE WATER-METER. [Illustration: FIG. 7.--The Babcock and Wilcox boiler (Fig. 6) illustrates this form. The Babcock and Wilcox; Messrs. Siebe, Gorman, and Co.; Messrs. Holmes and Co.; Messrs. Babcock and Wilcox boiler is kept at the door opened and closed.