The first wing of the building is by upright and circular saws, used fora variety of pur poses not immediately connected with the making of blocks. The only operation for this department is that of converting the rough timber, which is generally elm or ash, most commonly the former, into its proper scantling ; that is to say, squaring it by the upright or straight-cutting saw, and then, bf fi circular saw, cross-cutting it into a certain number of parallele pipedons, whose lengths may bear the required pro portion to the thickness of the log. Some of these pieces are again cut longitudinally; according to the thickness that may be required for the shell of the block,•especially those for single and double blocks, which of course are thinner than three and four fold blocks. This operation is performed by what is called a ripping-saw. The logs thus cut out are then taken into the second wing of the wood-mills, where the machinery peculiar for the construction of blocks is erected; and here the first process may be said to commence in making the SHELL.
This operation is performed by the Boring-Ma chine, which, by means of a centre bit applied to the middle of the shell, bores a hole for the centre pin of the sheave, while another bores one, two, or three holes, at right angles to the direction of the first, to admit the first stroke of the chisel, and, at the same time, to serve for the head of the mortice or mor tices, according as the 'intended block is to con tain one, two, or three sheaves. When thus bored, the log is carried from hence to the Morticing-Machine, which is an ingenious and striking piece of mechanism. The block being firmly fixed on a moveable carriage, the latter is so con • trived as to be made to advance cutting chisels, which are set fast in a moveable frame. Every time the frame, with the chisels, ascends, the block in its carriage advances a little, so as to present to the chisels a fresh surface of wood to be acted upon at each stroke of their descent; and this up and down motion is continued with such rapidity, that the chisels make from one hundred to one hundred and thirty strokes in a minute, until the 'prescribed length has been morticed out ; when, by raising a handle, which is done by a boy, the machine is stopped precisely when the chisels stand at their greatest elevation ; and are thus left in the proper position, ready to commence a second operation. No harm, however, would happen either to the block or the machi nery, should the attending boy neglect to stop the work at the proper time, or even to fall asleep, not withstanding the force and rapidity of the stroke ; for, by a particular contrivance, the farther advance of the block is stopped, and the chisels, therefore, act in full space, and cut only the air. It is, indeed, • a general characteristic of ,Brunell's machinery, to be so constructed as to carry with it a defence or protection against its own operations, and to coun teract all ill effects that might otherwise arise from • any neglect or inattention of the workmen.
The chips cut by the chisels are thrust out of the mortice by small pieces of steel attached to, and projecting from, the back of each chisel. They are each of them, besides, armed with two cutters placed at right angles to the edge, called scribers, which mark out the width of the chip to be cut by the chisel at each stroke. These scribers answer another purpose ; their cutting is so true as to leave the two sides of the mortice so perfectly smooth, as to re quire no further trimming or polishing.
The next process is to remove the block from the morticing machine to a circular saw, in order to have the four corners taken off, by which operation it is reduced to an octagonal shape. This saw being fix ed into a table or bench, the workman has nothing more to do than to slide each log along the surface of the table, in the direction of the line marked out for the saw to cut it.
The next operation is to place the block upon the Shaping Machine. This is perhaps one of the most ingenious and most effective contrivances in the whole machinery of the wood-mills. It consists principally of two equal and parallel circular wheels moving on the same axis, to which one of them is firmly fixed, but on which the other is made to slide ; so that these two wheels may be placed at any given dis tance from each other, and blocks of any size ad mitted between their two rims or peripheries. For this purpose, both rims are divided into ten equal parts, for the reception of ten blocks, which are firmly and immoveably fixed between the two wheels. When the double wheel with its ten attached blocks is put in motion, the outer surfaces of the blocks, or those which are farthest from the centre, strike with great violence against the edge of a chisel or gouge fixed in a moveable frame, which, being made to slide in a curved direction in the line of the axis, cuts those outward faces of the blocks to their proper curva ture, which can be altered in any way the workman pleases, by a contrivance attached to the cutting tool. As soon as the tool has traversed the whole length of the block, or over the space contained be tween the two peripheries of the wheels, the machine is thrown out of the gear, and its prodigious velocity checked by a particular contrivance. The ten blocks are then, by a single operation, and without remov ing them, each turned one fourth part round, and another fourth part of their surface brought out wards, which, being exposed to the cutting instru ment traversing in the same direction as before, have the same curvature given to these new surfaces. A third side is then turned outwards, and, after that, the fourth and last side, when the whole ten blocks are completely shaped, and ten other octagonal logs applied to the peripheries to undergo the same operation.