The year after Mr. Clement brought out his improved turning-lathe, he added to it his self-adjusting double driving centre-chuck, for which the Society of Arts awarded him their silver medal in 1828. In introducing this invention to the notice of the Society, Mr. Clement said, "Although I have been in the habit of turning and making turning-lathes and other machinery for upwards of thirty-five years, and have examined the best turning-lathes in the principal manufactories throughout Great Britain, I find it universally regretted by all practical men that they cannot turn anything perfectly true between the centres of the lathe." It was found by experience, that there was a degree of eccentricity, and consequently of imperfection, in the figure of any long cylinder turned while suspended between the centres of the lathe, and made to revolve by the action of a single driver. Under such circumstances the pressure of the tool tended to force the work out of the right line and to distribute the strain between the driver and the adjacent centre, so that one end of the cylinder became eccentric with respect to the other. By Mr. Clement's invention of the two-armed driver, which was self-adjusting, the strain was taken from the centre and divided between the two arms, which being equidistant from the centre, effectually corrected all eccentricity in the work. This invention was found of great importance in ensuring the true turning of large machinery, which before had been found a matter of considerable difficulty.