REPORT OF MEDICAL SECTION. 157 
the thread was rather loose ; anda still louder and shriller sound 
ensued when a knot of string was fastened to the thread. 
The same tube being adapted to the stop-cock of a water-sup- 
ply pipe, through which the current could be left to pass with 
great force, it was found possible to imitate every variety of 
blowing, whizzing, and musical murmurs, by varying the pressure 
on, or impediment in, the tube, and by altering the force of the 
current. When the current was strong, the least impediment 
caused a murmur ; but with weaker currents, greater obstructions 
became necessary for the same effect. A partial obstruction, 
which with a weak current gave a blowing sound, produced, with 
a stronger current, one of a more whizzing character. Grating 
or rasping sounds were best obtained by the effect of a strong 
current on aknotted thread across the diameter of the tube. The 
musical or uniform sounds resulted from a moderately strong cur- 
rent through a considerable impediment : increasing the force of 
the current, or the degree of obstruction, rendered the sound 
whizzing and imperfect ; diminishing the current or the obstruc- 
tion, converted it into a simple blowing. When asound was of 
an appreciable pitch, its note was high in proportion to the force 
of the current and the amount of the obstruction ; a fine forcible 
stream producing the highest note. Sometimes, however, with 
a strong current, a loud trumpet note would be set up, which 
wasnotaltered in pitch, but only in force, by changing the strength 
of the current. This kind of note produced vibrations of the 
tube below the impediment, perceptible to sight and touch, and 
the length of this portion of the tube seemed to affect the cha- 
racter of the note. This phenomenon precisely represented the 
purring sound and tremor sometimes perceptible in the heart 
and arteries. Musical sounds of a more variable character, like 
the cooing of a dove, the humming of an insect, or the whistling 
of wind, were produced with a weak current passing through a 
tube much obstructed. The pressure of a column of water only 
two or three inches high, was sufficient to give acute whistling 
notes, which were sustained, although varying, even when the 
water that passed only fell in drops. 
Bending the tube to an angleproduced a murmur, butno sound 
resulted from any curve that did not infringe on the caliber of 
the tube. A circular constriction by a thread drawn round the 
tube caused a murmur, which was blowing or whizzing accord- 
ing to the force of the current. 
_ When the tube with a weak current was pressed on at two 
points, the murmur was heard at the point where the pressure 
was greatest; and by increasing the pressure at one point the 
pressure was stopped at the other. When the current was strong, 
