Dr. Florence Robertson, checking a Humble-Truman Gravimeter. (J. B. Macelwane Archives, Saint Louis University)

According to Dr. Carl Kisslinger, former chair of the department of Earth and Atmospheric Sciences, a description of this gravimeter was found in a 1940s geophysical exploration text. The instrument is a Truman gravimeter, used by Humble Oil Company and usually called a Humble-Truman Gravimeter. The instrument probably got to Saint Louis University through Father Macelwane's close ties with the oil industry.

Quoting Dr. Kisslinger:
"I believe that Humble was doing exploration in the Libyan desert and had to clear out fast as the German army swept eastward. As I recall Fr. Macelwane's account, a pilot was about to take off when he saw the instrument, didn't know what it was, but it looked valuable. He put it in his plane and got out. I do not know the path by which it got to SLU, but Fr. Mac was well-known to the oil industry and I assume somebody at Humble decided to make it a gift."