There were two basic designs, subject to various modifications by other makers, of the geometric chuck in the nineteenth century. These were Ibbetson's, made chiefly by Holtzapffel, and this type (about which there was considerable controversy as to whether it had been originated by Hartley or Plant). Certainly most seem to have been made by Plant. The present example appears stylistically to have been made by some other person and subsequently to have been altered. It is still capable of good work.