From Toledo, Ohio, in April of 1938, inventor John L. Bloomheart filed for a U.S. patent on his “Contact Thermometer.” On March 26, 1940, he was granted U.S. Patent No. 2,195,019 (right), which noted that he had assigned his rights to Toledo’s Martha F. McKesson. She was the widow of Elmer I. McKesson, M.D., who had built much of his reputation on perioperative monitoring of patients’ vital signs. Using Bloomheart’s patent, the McKesson Appliance Company (plaque, top left) produced the wood-boxed “McKesson Dermalor” (middle left) for measuring skin or other contact temperature. Using “a Wheatstone bridge including an applicator tool having a high temperature-coefficient of resistance as a first leg thereof,” the Dermalor’s indicator needle swung through a “CENTIGRADE SCALE” (enlarged, bottom left) with 0.2 °C divisions of temperatures ranging from 20 to 42 °C or through the corresponding Fahrenheit range by divisions of 0.25 °F. Besides monitoring the temperature of human patients or veterinary subjects, the battery-operated Dermalor could be used for contact thermometry in the laboratory. (Copyright © the American Society of Anesthesiologists, Inc.)