[en] A variety of measurements has been made on the scars on some tube-on-flat impact wear specimens. The results have allowed examination of some of the assumptions made previously in formulating a theory relating the maximum wear depth to the wear volume for this geometry. The assumption that the shape of the scars would be cylindrical was reasonably borne out, as was the part of the theory which predicted that for a specimen pair the ratio of wear depths would be in the ratio of the wear volumes in the scars. The most encouraging result was that wear depths predicted by the theory using the measured wear volumes compared very well with the measured depths. The predicted depths averaged 5% less than the measured ones, with a range of from 3% more to 12% less. As a fraction of the tube wall, the percentages would be considerably smaller. (author)