Signedetched and white filled on front panel: VACUUM TUBE OSCILLATOR / TYPE 381 SERIAL NO. 11 / GENERAL RADIO CO. / CAMRBIDGE, MASS / LICENSED FOR RADIO LABORATORY / EXPERIMENTAL USE ONLY WHERE NO / BUSINESS FEATURES ARE INVOLVED / PAT. NO. 1113149 OCTOBER 6, 1914
Inscribedplate on top lid: GIFT OF / MR. GEO. E. CABOT / BOSTON
FunctionPossible function: the invention of the vacuum tube oscillator, consisting essentially of an amplifier with coupling between the output and the input and some definite means for regulating the frequency of oscillation. http://www.leapsecond.com/pages/marrison/