Roper's catechism for steam engineers and electricians .. (1899)
Roper, Stephen. [from old catalog], Keller, Edwin R., [from old catalog] ed, Pike, Clayton W., [from old catalog] ed · Philadelphia, D. McKay · leaf 371
r, as a rule. Forburglar-alarm and watch-clock systems six are, asa rule, sufficient, and sometimes a less numbermay be used. 350 ROPERS CATECHISM FOR THE TELEPHONE. The phenomenon of sound is caused by vibra-tions of the particles of air; its pitch is dependentupon the number of vibrations per… … what difficult to understand. Suppose that amass of air is set in vibration by a tuning-fork,and that we study the motion of a single particleof air by plotting on a flat surface. Let distancesto the right of the vertical represent time, andvertical distances represent the distance which…
Steam engineering · Electrical engineering
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