Six of the papers and discussions included in this volume were presented at a session on Radiography at the Fifty-second Annual Meeting of the American Society for Testing Materials, held in Atlantic City, N. J., June 27–July 1, 1949. This Session under the Chairmanship of L. W. Ball was sponsored by Committee E-7 on Non-Destructive Testing. The paper by W. W. Buechner, et al., entitled “An Investigation of Radiography in the Range from 0.5 to 2.5 Million Volts,” was not presented at this Session. It was published in ASTM Bulletin, No. 155, December, 1948, and appears here since the substance of the paper is pertinent to and not duplicated by any of the others. The paper by D. T. O'Connor and W. R. Maddy on “Radiography and Autoradiography by Photoelectrons” was presented before the members of Committee E-7 in 1949 in an informal session. These papers correlate late developments in the field of radiography.
