Excerpt from Proceedings, 1876 There was another point that he noticed in the drawing shown of the friction brake dynamometer; the rims of the brake wheels were made convex transversely like an ordinary belt pulley. He had found in running some brakes under various circumstances that they acted better if the rims were flat; the lubrication was then more equal over the whole surface. If the brakes ran very fast with a slightly convex rim, the oil was apt to get more in the centre of the rim, leaving the edges imperfectly lubricated; he had had difficulties with very wide brakes from that cause. He should be glad to know also what was the maximum power that had ever been absorbed by the brake shown in Fig. 17, which was stated to have been proportioned for 100 H. P. At 100 rev. Per min. The three brake wheels being each 5 ft. Diameter and 7 in. Wide, he found that the number of inches in their aggregate width (21 multiplied by the velocity of the rim in ft. Per min., and divided by the 100 H. P. To be taken ofi, gave as a result the constant number 330 per H. P.; but in a number of experiments which he had once tried with a brake of a rather smaller diameter than that, he had found that there was a great difficulty in keeping the rim cool if the constant number obtained in that way came lower than 700 per H. P. Taken ofi; which was about double the number obtained with the brake described in the paper. In other words, he should expect this brake to absorb only about 16 H. P. For each of its three wheels at the speed stated. Of course by a very careful lubrication the brake could be kept cool with the very low constant of 330 pertaining to the proportions given in the paper; but in running for a long time it was necessary to have a higher constant. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.