W. L. Stevens—Organ-Pipe Sonometer. 481 
Thus, the cord-length for C being one meter, we have for OF, 
J=944™; for D, =891™™, etc. Two octaves are thus marked 
off for the scale of equal temperament, with twelve division- 
lines to the octave, while on the other side are twenty-one to 
the octave. es 
ference in position of the bridges being easily detectible even 
hen the ear fails to distinguish between the two sounds. Ev- 
ery note in the two scales can thus be compared in a few mo- 
Metts, starting with C as key note. : 
The necessity for temperament, and yet the unavoidable 
derived key for purposes of comparison ; for example, that of 
G. For this purpose a separate strip (4,/”, fig. 2), properly 
marked off, is placed at the side of the central strip, the mov- 
able bridge being grooved below to slide over It. It is pre- 
The division-marks 4, 4, 4, }, 4, ete., each labeled with the 
name of the corresponding note, C’, G’, C”, BE”, G”, ete., as well 
