A Ford Bell stethoscope with a knight
spring mechanism which pulled the earpieces together allowing the
stethoscope to be held with one hand. The chest piece is made of
horn and the earpieces are of gutta-percha. The spring mechanism is
signed "Codman & Shurtleff
Boston". This rare combination of a bell stethoscope with knight's
spring is the only one I am aware of.
