Pipes produced in a similar manner, of which the material was a cement or imitation of stone, have likewise been brought into use.

Some years since Mr. Murdock took out a patent for the economical fabrication of pipes of real stone, the process combining the advantage of making solid cylinders at the same time. In forming a pipe or hollow cylinder of stone, instead of cutting out in useless scraps, or grinding to powder, the whole diameter of the bore, the patentee cuts out a core or solid cylinder, whose outside diameter is only about half an inch less than the inside diameter of the pipe. In like manner, when he intends to form a column or solid cylinder, or disc of stone, instead of breaking off, cutting, or chiseling away the superfluous parts of the stone, these parts are formed into a hollow cylinder, the core of which is the solid cylinder or disc required. Hence, if the stone is large enough to leave the outside parts of a proper thickness, these parts may be used as a pipe, and the core may either be used as a solid cylinder or column; or, by a farther operation, it may be converted into a pipe, and the cylinder cut out of it may again be converted into another pipe, which process may be continued until the core cut out is too small to be useful. 'I he following is the mode adopted by the patentee of accomplishing it: - he fixes the block of stone to be perforated in an upright position, and in the centre of the top of the block of stone, a step to receive the toe of a vertical spindle, which derives its motion from a pulley turning in plummer-blocks in a fixed frame above; this axis is considerably longer than the pipe or column to be formed, having the faculty of sliding vertically through the aforesaid horizontal pulley, over which it is suspended by a rope that passes round a vertical pulley, and thence is connected to a winch to wind up the axis at pleasure.

The saw employed is at the edge of a hollow cylinder (on the same plan as that described by us for trepanning, under the article Annular Saw), and this hollow cylinder is turned by the spindle through the medium of cross-arms, through which the axis slides; and, in order to give the requisite force to the annular saw, the top of the tube to which it is fixed is loaded, provided its own weight be insufficient: the motion given to the saw, though circular, is reciprocating. To effect this, a rope passes round the pulley at the upper part of the axis, and the two ends of the rope are conducted in opposite directions over two vertical pulleys, over which the two ends of the rope respectively fall, where they are each furnished with a cross-handle; one workman takes hold of one handle, and another workman the other, and pulling alternately the pulley at the top of the axis, together with the annular saw, is made to reciprocate circularly, cutting an annular groove in the block of stone. A barrel of sand and water is made to deliver these essential auxiliaries to the saw in the following manner: - it is directed to the upper end of the axis above the tube, which it enters, and runs down into the annular groove under the edge of the saw, whence it flows upward by the pressure of the continued descending current on the opposite side, and thus carries off the sludge clear of the saw.

Stone tubes of this kind were employed by the Manchester Water Works Company.

Elastic tubes of Indian rubber are extensively used for the transmission of gas and corrosive liquids; and they are admirably manufactured by Mr. Thomas Hancock, of Goswell-street Road. Mr. Thomas Skidmore, an American gentleman, whose process is a good one, is as follows: - Take a cylindrical rod of iron of the desired length, round this closely coil annealed wire in the manner of a spiral spring, care being taken that the edges of the coiled wire shall touch each other, but shall, at the same time, not be so firmly wound as to prevent its slipping off the rod: then cover the wire with tape spirally from end to end, and upon it lay strips of Indian rubber, wound in a similar manner, with their fresh cut and clean edges lapping upon each other. Then bind these down tightly with another coil of tape: after this withdraw the rod, and boil the tube in water for an hour or two; when cool, remove the wire and tapes, and an Indian rubber tube will be produced, which, though rough, will be perfectly sound if the process has been properly conducted.

The method of making leaden pipes has been described under the article Lead; but we will take the opportunity of mentioning in this place, that it appears, by some recent experiments made by Mr. Jardine, of the Water Company's Works at Edinburgh, that a lead pipe of 1 1/4 inch bore, and the fifth of an inch in thickness, was found capable of sustaining a power equal to that of a column of water 1000 feet high, which is equal to 30 atmospheres, or 420 pounds per square inch of internal surface. With a pressure of 1200 feet it began to swell, and at with 1400 feet it burst. In another experiment, a pipe two inches in diameter, and one-fifth of an inch thick, sustained 800, but burst with 1000 feet pressure.

Wooden pipes for the conveyance of water, are bored by means of large iron augers, worked by one or two men, who commence with a small bore, and increase it as the work proceeds, by changing the auger to a larger size, which are sometimes extended to eight or nine inches in diameter. The tree in the process of boring, is laid horizontally upon tressels constructed to support and hold it firmly, and the augurs are similarly supported and guided, so as to pass cen-trically through the tree. The manual operation is of course slow, and extremely laborious: machinery, worked by steam, or other power, has therefore been introduced to execute the work. The piece of timber, or tree, is held down upon a frame by chains passing over it, and round two windlasses. The frame and tree, thus bound together, run upon small wheels traversing two long beams, called ground-sills, placed on each side of a pit, dug to receive the chips made by the borers. At one end they are connected by a cross-beam, bolted upon them; this supports the bearing for a shaft, the extremity of which, beyond the bearing, is perforated at the end of a square hole to receive the end of the borer.

The timber and carriage are made to advance towards the borer by means of ropes; one rope being made to wind up, while the other gives out and draws the carriage and piece of timber backwards and forwards according as the wheel is turned. The weight of the borer is supported by a wheel turning between uprights fixed on a block, the end of which rests upon the ground-sills: it is moved forward by means of two iron bars, pinned to the front cross-bar of the carriage. The distance between the wheel and the carriage may be varied by altering the iron bars and pins, so as to bring the wheel always as near as convenient to the end of the tree. The shaft may be turned by any first mover. When the borer is put in motion by turning the wheel, he draws the tree up to the borer that pierces it; when a few inches are bored, he draws the tree back by reversing the motion of the wheel, in order that the borer may throw out its chips; he then returns the tree, and continues the process until the work is finished: the borer, in this case, be its si2e what it may, is of the same shape as that of a common auger.

We would suggest the employment of spiral augers instead of the common, as the former would deliver the chips as it proceeded, and not require withdrawal until the perforation was completed.

Some years ago Mr. Howel, of Oswestry, invented a machine for making concentric wooden pipes out of one piece of timber, the mechanism of which was on the same principle as that we have described under Mr. Murdock's patent for sawing out stone pipes, who, it appears, derived the principle of operating from Mr. Howel, and modified it so as to adapt it to the cutting of stone.