The Lateral Vibration of Bars. 581] 
the lower. dele 5 is from the same string plucked at 4 
and observed at 4. The simple harmonic components are now 
limited practically to the ape aaa and octave, the latter 
being too sharp by the inter val 1 — 
Vibration-jorms and Timbre. 
An interesting point which arose in the course of the 
investigation was that the vibration-forms were independent 
of the quality of the tone heard, and of the presence on the 
same frame of strings resonating with the plucked string. We 
photographed the motion of a gut string of a guitar (the 
G string) under three conditions: (1) with the other strings 
removed ; (2) with the other strings on the instrument and 
tuned to resonate : the lowest string to the octave below the 
plucked string, the next two to unison with it, and the two 
upper strings to the octave above ; (3) the string mounted on 
a rough wooden frame, on which it gave a tone of ver y inferior 
quality. The vibration-forms followed exactly the same 
course in all three cases. This seems to imply that the 
supporting frames take the same component vibrations from 
the string, but act differently in their way of communicating 
to the air the vibrations imparted to them. The vibrations of 
the string are given to the air via the scunding-board. It 
would seem that the selection of the harmonics, determining 
the good or bad quality of the tone heard, is made at the 
transference from sounding-board to air, and not at that from 
string to sounding-board. 
Queen’s College, Belfast. 
August 2nd, 1904. 
—_ =z + 
LVI. On the Lateral Vibration of Bars. 
By C. A. B. Garrett, University.College, Nottingham*. 
| [Plate XVIL] 
HE problem of the lateral vibration of bars has been 
treated very fully by Lord Rayleight. He also shows . 
that in the case of a bar fixed at one end we can get an 
approximate expression for the frequency of the fundamental 
vibration, if we assume the shape of the vibrating bar to be 
the same as if it were pulled aside by a force at the end. 
Further, he goes on to show{ that we get a closer approxi- 
mation, if we assume the shape to be the same as if pulled 
a Communicated by Dr. E. H. Barton. 
+ ‘Theory of Sound,’ vol. i. chap. viii. 
t Loe. ert. § 182. 
