Following J.J. Lister's work on the principle of aplanatic focal points, microscope makers were free to create ever larger angular apertures for their objective lenses. However, with this increase in aperture came the problem of fine focusing these high power lenses; the standard method - by rack and pinion - was sufficient only if extremely well-made and fitted. Other methods, such as Ross's short lever focusing, or Hugh Powell's long lever focusing were tried, but another alternative was William Ladd's fusee chain-driven focusing. The purpose of this method, as laid out by Ladd in a communication to the Microscopical Society of London on 16 April 1851, was to render the exercise of focusing the microscope "smooth and totally free from loss of time". The Jury of the Great Exhibition of 1851, where several instruments employing this method were shown, agreed that this was indeed the happy result of the innovation and awarded Ladd an honourable mention. They further noted, however, that perhaps it was not quite the innovation it purported to be, remarking that it had in fact been "applied to the microscope many years since by Mr Julius Page". Notwithstanding, and partly because little information can be found about Mr Page beyond the fact that he was a member of the Microscopical Society of London, it is with Ladd that this method of focusing is most associated; its most significant incarnation beyond on instruments bearing Ladd's name was its use on the Smith, Beck and Beck "Universal" microscope, described in detail by Richard Beck in his The Achromatic Microscope of 1865.