This is a standard spring scale used by Cleve H. Shaffer for his experiments with liquid propellant rockets to measure their thrusts. It has a 0 to 400 pound capacity. Schaffer's experiments were made during 1926-1932. He was thus contemporary with Robert H. Goddard but there was no connection between the two.
Shaffer designed and constructed a number of motors, but the details are unknown. Only static tests were carried out and no flight attempts were made. Shaffer was given permission by the Army to conduct the tests on a deserted beach at Fort Barry in Marin County, California. But due to the lack of Army interest and the high expense of the work, he abandoned his experiments. The scale was donated by Schaffer to the Smithsonian in 1961.
Cleve H. Shaffer