" " 2 24 " " " 15 deg.
" " 3 36 " " " 10 deg.
" " 4 36 " at irregular distances.
" " 5 36 " distances t= 101/2 deg., t'=l0 deg.,t''=91/2 deg.
" " 6 36 " " 11 deg. 10 deg. 9 deg.
" " 7 36 " " 16 deg. 14 deg.
" " 8 36 " " 161/2 deg. 131/2 deg.

Circle No. 8 produces the two notes of circles 1 and 2; circle No. 7 the
same, but the low note is stronger than in 8.

Circle 6 produces the notes of circles 1 and 3, and so does circle 5,
but in the latter the low note is stronger than in 6.

Circle 4 produces a noise approximating only to the note of circle 3.

By pulling out one of the buttons of the wind chest, we admit the air
through eleven holes at a time, having an angular distance of 30 deg. and
directing it against the corresponding circle of holes on the turning
disk. If the arrangement of holes is not repeated identically twelve
times on the same circle, we cannot, of course, make use of the above
arrangements of holes of the wind tube, and we must then employ one of
the movable brass tubes, which communicate with the interior of the wind
chest by means of rubber tubes and stopcocks. The experiment with disk
1, circle 4, for example, requires the use of one of these two tubes,
while the perforated wind tube of the wind chest may be used with all
the other circles of the same disk.

B.