Sphyg′mo-scope.
An instrument for rendering the arterial pulsations visible.
It is said to have been invented by Galileo, who, by placing one end of a light mirror upon the artery leading to the thumb and the other upon a fixed object, caused the image of a sunbeam reflected from the mirror on an opposite wall to vibrate in unison with the pulse.
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Pond's sphygmoscope. |
Fig 5381 is a view of
Pond's sphygmoscope, patented April 6, 1875 The essential parts of the instrument are a liquid reservoir or receptacle; an opening in the same, which, whether closed by an elastic and yielding membrane or not, is to be applied to or over the pulsating body; and a fine transparent terminal tube, communicating at one end with the reservoir or receptacle, into which tube the liquid, when the open end of the receptacle is pressed on the pulsating body, will enter, and will therein rise and fall to accord with the movement of the pulsating body, said movement being considerably magnified by the moving liquid, owing to the small diameter of the tube in which it is received.