The blocks, shells, and sheaves, being now finish. ed, we have to consider the iron pins for them. The small blocks, indeed, are fitted with pins of hard wood. The iron pins are first forged to the true size and shape, having a cylindrical part of sufficient length to pass through the shell of the block ; and•a square part, which is to be drifted into one of the cheeks of the shell, to prevent the pin from turning round. They are then taken to, No. 18. The turning lathe, where the iron pins are turned by a slide rest, in a manner something si milar to the facing lathe : they are then covered with spiral scratches from the scoring of the tool. These are rounded by, No. 19. The polishing engine. The pin is fixed into the lower cud of a vertical revolving axis, and forced down into a sort of die, immersed in oil, hold ing three pieces of hard steel, between which the pin is pressed as it turns, and by that means is perfect ly polished.
The wood pins are cut by the circular saw into oc tagon pieces of the proper length. These are put into a common lathe, having adapted to it a simple tool, called a witchit, which quickly cuts the pin to a true cylinder, except a short piece at the end, which is left of an octagon form to be inserted into the cheek of the block, in order to prevent the pin from turning. We have not numbered this as a separate machine, because it • is used in the common way of making blocks, being applied to the same lathe in which they turn the sheaves.
Besides all these machines, the block mills contain three ethers ; one for large blocks, and two for dead eyes.
No.20. The•ormer is a complete apparatus for Go ringverylarge ho/csinanyposition. It is used forblocks or a size beyond what the regular machines are calcu lated for ; some of these blocks being as large as 54 inches in length, with 4 sheaves. The shells_ for these are made up of pieces. They are used for the mast hulks; and by them the masts of the largest ships are suspended while they are fixed in their situation. The number of these blocks which is required, is not so great as to make it worth the expellee of a set of ma chines for them ; but the workmen avail themselves of all the assistance which they can derive from the largest of the three sets of machines, and perform the rest by hard labour. This large boring machine is the• only one exclusively appropriated to large blocks.
J No. 21. The machinesfor Junking dead eyes. Af ter the scantling for these has been cut out by the machines before described, they are bored in the bo ring machine : The angles are then removed by the corner saw ; and they are next put into a machine which shapes them, and cuts the score round them.
They have two of these machines ; the first making dead eyes from five to nine inches diameter, and the second being adapted to those from 10 to 19 inches.
Thus we have given a general idea of the objects, of this really interesting mill ; but a general idea of the whole is all that we can hope to give, from the li.. mite we have been obliged to prescribe to our Plates. We shall seleCt a few of the most curious of the ma chines, and give perspective drawings of them, reser ving others for a future opportunity. On entering, the block mill, the spectator is struck with the mul tiplicity of its movements, and the rapidity of its ope rations. The elegant structure of the small machines, strike the eye as objects of ornament as well as.utili. ty. On this score, great credit is due to Mr Mauds. Icy for the perfection of workmanship displayed, throughout these works ; all the bearings, sliders, and fittings, being executed in the most accurate manner, so as to move freely, but without shake., This accuracy is essential in these machines, ,as they are contrived so as to adapt themselves to blocks of many different sizes and shapes ; for if all the.fittings were not very correct, the parts would be insufficient. to restrain the large blocks, while they were clumsy, and inconvenient for •the small' ones. This will appear from the great number of different blocks' made at these mills, which are as follows:..
Thick blocks, • varieties—single sheaves, double: sleives, treble, and fourfold. The sizes of each va riety are from 4. inches to 28 inches in length ; but: only the three first•varieties are wholly, made by the machine ; the fourfold, which are chiefly made with: the hand, caiLoilly have the assistance of those, ma chines which will form their parts :.their sheaves and pins, however, are completely made by the machines.. These make about 72 sizes. Thin blocks are. the same, but.with nar row sheaves : these. run from. G to 26 inches in length, 4.8 Clue garnet and clue line blocks are of a peculiar construction, introduced by the inventor of the machinery. (See the ar ticle BLocK) 10, Sister blocks, 20 .
• Top sail sheet blocks; 20 Fiddle or viol blocks, 24.
Jack blocks, 20 214.