avant la lettre, Fig. 6a.
Fig. 6a. [cropped to square]
Wheeler P. Davey (1886-1959 *). “Radiography of Metals.” Transactions of the American Institute of Mining Engineers 53 (1916) : 150-160
University of California copy, digitized October 31, 2012
...as the inequalities in thickness due to the uneven surface were at least as great as those due to porous or frothy structure. *
avant la lettre; frothy structure; grays; radiography; skiagraphy
W. P. Davey