This allowed a shorter train and stronger wheelwork to be used, securing more certain action, and involving less risk of derangement.
Alexander Bain in 1846 suggested enclosing the wheelwork in the rotator.
In Thomas Walker's harpoon or frictionless log, introduced in 1861, the wheelwork was enclosed in a cylindrical case of the same diameter as the body of the rotator or fan, and the latter was brought close up to the register, forming a compact machine and avoiding the use of the 6-ft.
The case A contains the registering wheelwork and a sounding bell.
Case A contains the wheelwork, and case E the spindle and steel ball FIG.