On circle 1 24 holes.
" " 2 36 "
" " 3 23 "
" " 4 12 at an angular distance of 10° from the holes
of circle 3.
" " 5 12 holes at an ang. dist. of 20° from those of circle 3
" " 6 12 " " " 0° "
" " 7 12 " " " 15° "
" " 8 12 " " " 15° "
1. If from the same side two currents of air at an angular distance of
15° are directed against circle No. 8 of 12 holes, we obtain the octave
of the note produced by the same circle if only one current is used.
The wind-chest is provided with a special arrangement for this
experiment. By pulling out button 8, we give vent to 12 currents of air
spaced like the twelve holes of the disk; on pulling out button 9 we
also produce 12 currents, but they are situated just between the first.
Each of these two buttons pulled out alone will produce the same note
corresponding to 12 holes, but drawn together they produce the octave,
or the note of circle 1.
2. If two currents of air are directed against two similar circles whose
holes are situated on the same radii, we obtain the same result.
In this experiment, circles 7 and 8 are sounded by pulling out buttons 7
and 9.
3. When two currents of air are directed on the same radius against two
circles of similar holes arranged alternately, these circles sounded
simultaneously will produce the octave of the note which one of them
would give alone.
This experiment is performed by sounding circles 6 and 7 and pulling out
buttons 6 and 7.
4. If we direct three currents of air on the same radius against three
similar circles having holes alternating by a third of the distance
between two holes of the same circle, the three circles together produce
the fifth of the octave (Note 3) of a single circle.
Circles 3, 4, and 5 sounded together emit the note of circle 2.
(By sounding only two circles, 3 and 4, or 4 and 5, we make the same
experiment with two circles as disk No. 2 enabled us to make with
circle 8 alone; also, by sounding circle 3 alone, we obtain the note
corresponding to 12 holes; then pulling out button 4, the notes
corresponding to 12 and 36 holes are heard suddenly and very strongly;
but as soon as circle 5 is sounded also, the note of 12 disappears
completely, and we have left only that corresponding to 36 holes.)