Bramah's indefatigable spirit of invention was only stimulated to fresh efforts by the success of his lock; and in the course of a few years we find him entering upon a more important and original line of action than he had yet ventured on. His patent of 1785 shows the direction of his studies. Watt had invented his steam-engine, which was coming into general use; and the creation of motive-power in various other forms became a favourite subject of inquiry with inventors. Bramah's first invention with this object was his Hydrostatic Machine, founded on the doctrine of the equilibrium of pressure in fluids, as exhibited in the well known 'hydrostatic paradox.' In his patent of 1785, in which he no longer describes himself as Cabinet maker, but 'Engine maker' of Piccadilly, he indicated many inventions, though none of them came into practical use,--such as a Hydrostatical Machine and Boiler, and the application of the power produced by them to the drawing of carriages, and the propelling of ships by a paddle-wheel fixed in the stern of the vessel, of which drawings are annexed to the specification; but it was not until 1795 that he patented his Hydrostatic or Hydraulic Press. Though the principle on which the Hydraulic Press is founded had long been known, and formed the subject of much curious speculation, it remained unproductive of results until a comparatively recent period, when the idea occurred of applying it to mechanical purposes. A machine of the kind was indeed proposed by Pascal, the eminent philosopher, in 1664, but more than a century elapsed before the difficulties in the way of its construction were satisfactorily overcome. Bramah's machine consists of a large and massive cylinder, in which there works an accurately-fitted solid piston or plunger. A forcing-pump of very small bore communicates with the bottom of the cylinder, and by the action of the pump-handle or lever, exceeding small quantities of water are forced in succession beneath the piston in the large cylinder, thus gradually raising it up, and compressing bodies whose bulk or volume it is intended to reduce. Hence it is most commonly used as a packing-press, being superior to every other contrivance of the kind that has yet been invented; and though exercising a prodigious force, it is so easily managed that a boy can work it. The machine has been employed on many extraordinary occasions in preference to other methods of applying power. Thus Robert Stephenson used it to hoist the gigantic tubes of the Britannia Bridge into their bed,[2] and Brunel to launch the Great Eastern steamship from her cradles. It has also been used to cut bars of iron, to draw the piles driven in forming coffer dams, and to wrench up trees by the roots, all of which feats it accomplishes with comparative ease.