George Ludwig's first ultrasound apparatus in his gallstone experiments.
An A-mode "ultrasonic Locator" designed by Ludwig and made by the General Precision Laboratories, Pleasantville, New York.
The power supply is housed on the left and the electronic circuitry and display oscilloscope on the right.

Following are pages 1 and 2 of the sales information leaflet of Ludwig's apparatus which was marketed commercially for "use in Medicine and Biology" (around 1950). Suggested usage already included detection of heart motion, blood vessels, kidney stones and glass particles in the body.

Images courtesy of the Ludwig family.

Back to History of Ultrasound in Obstetrics and Gynecology.