The strength of the source at installation (May, 1956) was approximately 1500 curies. The measurements include accurate assessment of room protection, backscatter factors, build-up in the superficial layers, leading to the computation of overall field factors relating the standard output in air to the dose rate in rads per minute at the "100" level for any given field. Central axis percentage depth doses were in good agreement with reported values, as were effects of field elongation on depth doses.