ABSTRACT
The stethoscope that he subsequently adopted was a cylinder of wood, an inch and a half in diameter and a foot long, perforated longitudinally by a bore three lines wide and hollowed out into a funnel shape at one end to the depth of an inch and a half. The double stethoscope of Dr. Leared, shown at the International Exhibition of 1851, was a great improvement. It consisted of two gutta-percha tubes attached to the chest-piece at one extremity and at the other to the ear-pieces. The attachment of a rim of soft rubber to the chest-piece, as devised by Dr. Snelling, is of advantage in applying it more closely to the inequalities of the chest. In most of the instruments now made the rubber band which served to draw the two tubes together is replaced by a spring. Great care is required in the construction of the stethoscope, and many defective ones are sold.
