This is Part II of a paper read by Prof. Ball, who is Chairman of Committee D-13 of the American Society for Testing Materials, at the Papers Session of that Committee held in New York City, Oct. 21, 1937.Part I was devoted to a description of the mechanical features, and essential information as to the operation of a selected, list of 11 abrasion and wear testing machines. Part I was published in the December, 1937, Bulletin of the A. S. T. M.