In his patent of 1802, we find Bramah making another great stride in mechanical invention, in his tools "for producing straight, smooth, and parallel surfaces on wood and other materials requiring truth, in a manner much more expeditious and perfect than can be performed by the use of axes, saws, planes, and other cutting instruments used by hand in the ordinary way." The specification describes the object of the invention to be the saving of manual labour, the reduction in the cost of production, and the superior character of the work executed. The tools were fixed on frames driven by machinery, some moving in a rotary direction round an upright shaft, some with the shaft horizontal like an ordinary wood-turning lathe, while in others the tools were fixed on frames sliding in stationary grooves. A wood-planing machine[5] was constructed on the principle of this invention at Woolwich Arsenal, where it still continues in efficient use. The axis of the principal shaft was supported on a piston in a vessel of oil, which considerably diminished the friction, and it was so contrived as to be accurately regulated by means of a small forcing-pump. Although the machinery described in the patent was first applied to working on wood, it was equally applicable to working on metals; and in his own shops at Pimlico Bramah employed a machine with revolving cutters to plane metallic surfaces for his patent locks and other articles. He also introduced a method of turning spherical surfaces, either convex or concave, by a tool moveable on an axis perpendicular to that of the lathe; and of cutting out concentric shells by fixing in a similar manner a curved tool of nearly the same form as that employed by common turners for making bowls. "In fact," says Mr. Mallet, "Bramah not only anticipated, but carried out upon a tolerably large scale in his own works--for the construction of the patent hydraulic press, the water-closet, and his locks--a surprisingly large proportion of our modern tools." [6] His remarkable predilection in favour of the use of hydraulic arrangements is displayed in his specification of the surface-planing machinery, which includes a method of running pivots entirely on a fluid, and raising and depressing them at pleasure by means of a small forcing-pump and stop-cock,--though we are not aware that any practical use has ever been made of this part of the invention.