March 10, 1964 The problem of friction and wear between solid bodies is about as old as the human race. The early Egyptians and Romans had discovered the utility of lubricants in reducing friction and wear during a period many years B. C. From the fall of the Roman Empire until the Renaissance, I ittle new information appeared. A major break-through occurred in establ ishing the laws of friction (friction independent of area and proportional to load) through the work of Leonardo da Vinci (1452 - 1519), Amontons (1699) and Coulomb (1785). While most of the studies until this time were based largely on a mechanistic approach, a new trend was initiated in the 1930's by F. P. Bowden and D. Tabor wherein the physics and chemistry of the problem were treated as well. Since then, a large I iterature has been buil t up deal ing with such problems as metal transfer, molecular theories to explain wear, local welding between contacting surfaces, interlocking theories, wear-rate studies, the development of various test methods, effects of surface films, fretting phenomena, effects of temperature and environmental conditions, abrasion, surface energy relations, etc. The I ist of contributors in this field is indeed too long to cite here in any detail. Among those that might be mentioned, however, are R. Holm, G. A. Tomlinson, H. Ernst, M. E. Merchant, 10M. Feng, J. K. Lancaster, W. Hirst, F. T. Burwell, D. W. Baker, F. D. Brailey, E. R.