Signedunsigned
Inscribedon case: INVAR TAPE / 44M BY 0.5M / CRUFT LABORATORY
FunctionThis tape is made with a metallic alloy known as invar, an alloy of nickel and steel that possesses a very low coefficient of expansion when submitted to thermal variations. This expansion invariance was essential in making accurate measurements.
Historical AttributesThis measuring tape was used for the velocity of light experiment done by Wilmer Anderson at the Lyman laboratory, Harvard University.
This tape was twice calibrated by the Department of Commerce National Bureau of Standards, the latest one Test no. 89518 6/8/40
ProvenanceFrom the Department of Physics, Cruft Laboratory, Harvard University.