Another implement prepared, in the course of the winter, for the Bell Rock work-yard, was the Carpenter’s jack, used for raising ships upon the blocks or props for the purposes of repair. This machine, which is simple in its construction, and direct in its application, consists of a rack and pinion, enclosed in a frame of oak timber, strongly bound with iron, as represented in Plate X. By working the handle of the jack, the stone-cutter is enabled, without the assistance of his fellow workmen, to turn and lay the heaviest stone to his hand. This apparatus the writer first saw used to much advantage, by the quarriers at Portland Island, in the year 1801; and though it had not perhaps at that time been put into the hands of the stone-cutter, it was obvious that it might also be applied to his purpose with equal effect. It may further be noticed, regarding this useful implement, as strongly marking the prejudices of habit, that Mr Mylne, the proprietor of Mylnefield Quarry, who, with enlightened views, furnished his works with machinery of the very best description, among other articles, provided a number of these jack-machines for his quarriers, but, for a long time, they could not be induced to make use of them. One of the men, however, happening, of his own accord, to apply the jack in turning a heavy block, its utility soon became apparent; and Mr Allan the manager, who had previously taken considerable pains to get the jack introduced, was at length not a little pleased to find it, after having been laid up in store as useless, in much request throughout that extensive quarry. [Sidenote: Lewis Bat.] A Lewis Bat, of some form, for lifting large stones, is believed to have been known to the ancients. But that now in common use is generally understood to have been at least improved by the French engineers, who, in honour of their Sovereign, gave it the name of Lewis. This useful implement is so universally known in practice, for its great utility in building with heavy materials, that it is hardly necessary to do more than simply allude to it. It consists of five pieces of iron, three of which, forming a dovetail, like an inverted wedge or the keystone of an arch, are inserted into a corresponding hole cut in the stone. The fourth is the bolt connecting the shackle-piece, by which the weight is suspended, as will be better understood by referring to the sketch or diagram illustrative of it in Plate XI. Of this implement, it became necessary to furnish several dozens, as well from the variety in the weight, as from the figure of the stones, many of them requiring two Lewises to produce a proper balance. But the number was more particularly encreased, from the different sets required for the workyard, the stone-lighters, and for the Bell Rock, where it was necessary to provide against loss, to which this service was so peculiarly liable. [Sidenote: Moulds.]