Estimated Date: 1901
Name: Dr. Kehlers Improved Stethoscope
Manufacturer: Becton Dickinson and Co
Description: 2” diaphragm head with engraving on metal part as above plus Pat dates of May 4, 97 and June 25, 01. It is unique in that the V shaped connectors to the rubber tubing are attached to the head with a swivel device.
Reference 1: 263