On the sounds caused by the circulation of the blood : being a thesis read in the University of Dublin for the degree of M.D., at the winter commencement, 1860 / by Arthur Leared.

  • Leared, Arthur, 1822-1879.
Date:
1861
Catalogue details

Licence: Public Domain Mark

Credit: On the sounds caused by the circulation of the blood : being a thesis read in the University of Dublin for the degree of M.D., at the winter commencement, 1860 / by Arthur Leared. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    5/24 (page 5)
    soundj bruit de soufflet, might also be heard in all parts of the reservoir. If the stethoscope was so held that the jet of water impinged upon it, a louder sound, but still a distinct bruit de soufflet was produced. In this experiment the stationary water was forcibly pene- trated by the moving column, while, owing to the mobility of the fluid, sufiicient friction occurred between its particles to give rise to low-pitched sounds—murmurs. The size of the reservoir precluded the possibility of friction of the water against its sides being concerned in causing sound. In order to test the effect of viscidity of the fluid upon sound so produced, the experiment was modified as follows:—The apparatus having been filled with glycerine instead of water, the same motions were performed. The first thing obvious on listening with the stethoscope was the comparative difii- culty of producing sound. But when the india-rubber bottle was compressed very strongly, a faint sound, resembling the first sound of the heart, was heard near the mouth of the tube. When, however, the moving column was allowed to strike the stethoscope, a loud sound, exactly resembling the heart's first sound—and therefore presenting a striking- contrast with the sound produced by water under similar circumstances—was heard. In this exj)eriment, the divisibility as well as the mobility of the fluid was greatly diminished by its increased viscidity and specific gravity. The impact between the fluid forcibly expelled from the tube and the fluid in the reservoir was there- fore more complete than in the case when water was employed. Hence a suiEcient concussion occurred between the opposing particles to give rise to a sound of a very different character from that formed by friction between the particles of water. It was perfectly obvious, in both experiments, that the india-rubber bottle and tube being attached at the bottom, and a stethosco])e being an-auged so as to perforate the reservoir; but the pressure of the fluid gi'catly increases the difficulty of producing sound. I have been always careful to eliminate any extrinsic sound, such as that from compressing the bolitlc, from consideration.