Signedetched and black filled on front panel, center: CATHODE-RAY OSCILLOGRAPH / TYPE 224 SERIAL NO. 2618 / 115 VOLTS 150 WATTS 60 CYCLES / ALLEN B. DU MONT LABORATORIES, INC. / PASSAIC, N.J., U.S.A.
Inscribedstamped in yellow on side: 100 - 0433
FunctionThe oscillograph or oscilloscope is an electronic device that is used to observe the shape of an electric signal.
For more information on the electron oscillograph, see the wikipedia page here.