Tyndall, John, 1820-1893 · New York : Appleton · leaf 111
you are already acquainted. The disks of the twosirens have a common axis, so that when one disk rotatesthe other rotates with it. As in the former case, the num-ber of revolutions is recorded by clock-work (omitted in thefigure). When air is urged through the tube t the upper 1 It is hardly… … THE DOUBLE SIREN. 105 siren alone sounds; when urged through t, the lower oneonly sounds; when it is urged simultaneously through tand t, both the sirens sound. With this instrument,therefore, we are able to introduce much more varied com-binations than with the former one. Helmholtz has…
Sound
Internet Archive · California Digital Library · Public Domain Mark 1.0. Free to use for anything.
