Sir Samuel Bentham now returned to the army, and by his own choice was appointed to the protection of the eastern frontier of Siberia, his command extending from the northern part of the Ural Mountains to the confines of Russia in the Chinese dominions. After holding this appointment for a couple of years, during which period he established schools for his troops, and introduced other improvements into their condition, Bentham obtained leave of absence to visit England. Here commences another epoch in Sir Samuel's life. Arrived in England, he found his brother Jeremy absorbed in investigations relative to jurisprudence. Jeremy, however, had not forgotten his brother's Panoptican, but had proposed its adoption for the County Gaol of Middlesex. This led to some explanations with the ministers, who ultimately entrusted Jeremy Bentham with a thousand convicts, of whose labour he was to make the best use he could. In the meanwhile Samuel went to visit the principal manufactories in England; he found that steam-engines were used for giving motion to machinery for spinning cotton, but in no case were they applied to machinery for the working of wood, metal, &c.; nor, in fact, were there any mechanical apparatuses for saving labour, with the exception of turning-lathes, and some boring tools worked by horses, for making ships' blocks. Bentham therefore patented, in 1791, his machinery for planing and making mouldings, specifying the improvements which he had made on the machine constructed ten years before for Count Demidoff. His brother's arrangements for the industrial employment of convicts having been concluded, Sir Samuel considered that the most profitable means of employing them would be the working of machines for saving manual labour, which at the same time ensured accuracy of work; he therefore exerted his mechanical genius to perfect several engines he had previously contrived in Russia, and patented his inventions in the specification (No. 1951). This specification includes machines for sawing, boring, and many other operations necessary for the working of wood or metal.