BLOCK MACHINERY immense number of blocks employed in the navy, and the great importance of having them accu rately and substantially made, in order to insure their ready performance in every unfavourable situation which the tackling of a ship is exposed to in bad weather, render the manufacture of these articles of far more importance than the generality of our read ers would imagine, from the appearance of so simple an implement. Cases constantly occur at sea, in tem pestuous weather, where the failure of a single block may put the vessel in imminent danger, by prevent ing the setting of her sails, or other important ope rations. At all times, the saving of labour on board a ship will be very great, from having the numerous blocks of her rigging well made ; for it is well known to mechanics, that, in any system of pullies, a consi derable portion of the purchase they would otherwise exert, is lost in the friction of the sheaves upon their pins, and against the inside of the shell of the block, as well as in overcoming the rigidity of the ropes ; for these, if tight laid, that is hard twisted, will not readily bend over small sheaves, but will take a con siderable power to force them into the sudden curva ture. Hence it follows, that blocks, with small pins made of iron, the sheaves large, and coated or bushed with metal, and all points of contact of the sheaves and shell made accurately, and using slack made ropes, will be the best means of diminishing the friction, and, at the same time, rendering the apparatus durable, a circumstance of equal importance to the seaman.
These, and other circumstances, induced govern ment in 1802, on the recommendation of General Bentham, to attend to the suggestion of Mr Mark Isambard Brunel, a gentleman who had at that time invented and taken out a patent for a complete set of machines for the manufacture of every part of ship blocks. He consequently employed Mr Maudslay of London to erect from his designs an extensive suite of machinery in the arsenal at Portsmouth, for the fabrication of these articles.
These machines were set to work in 1801, and have been in constant use ever since. They consist of 44 machines, forming in the whole the most com plete and perfect system of manufacture by machine ry, of any establishment which is to be met with in this kingdom, or perhaps in the whole world, at least of an article which has so many different parts to be formed in hard materials, and has such a great variety of sorts and sizes to be made by the same machines, not less than 200 kinds of blocks being manufactured at these works. The mechanical contrivance, as well
as the elegant construction of the block machines, is at least equal, if not superior, to any examples of prac tical machinery, which we have at present contempla ted for the succeeding volumes of our work. Under these circumstances, we do not think our readers will require from us any apology for extending this ar ticle beyond the bounds which the manufacture of a ship's block alone would deserve. To our mechani cal readers, this article, and its accompanying Plates, will be highly acceptable, as presenting them with a number of curious machines, which may in their hands, at the expiration of the patent, be rendered applicable to a great variety of other similar opera tions in the mechanical arts, which arc now perform.. ed by manual labour.
Before proceeding to the detailed description of the drawings of the most striking of these machines,. we shall give a general outline of the operations which a block and its sheave, or shiver, are subjected to, that the connection of one machine with another may be more clearly understood. The machines are put in motion by a capital steam-engine of 32 horses' power, erected by Messrs Boulton and Watt. The whole establishment contains 44. machines, as before stated, which form three sets, that is, three blocks of different sizes may be proceeding in all their stages at the same time, though in some of these stages one machine operates at the same time upon two, or even ten blocks. The building or block mill is of great length, having the steam-engine in the centre, which therefore divides the house into three lengths : the centre, which is a large and tall house, for the engine, and two wings for the mills. One of these wings is devoted to the machinery for sawing and converting the timber into scantling, that is parallelopipedons, of the proper size to form the different blocks ; this de partment contains seven large sawing machines. On the opposite side of the building are the machines which form the blocks and their sheaves : These are smaller and more delicate engines, being 37 in num ber. It is to ,these we shall chiefly turn our men.: tion in this article, because they are the real block machinery ; the other seven, though no less deserving of notice from their ingenuity, and perhaps superior from their general utility, are only sawing-machines, and equally applicable to sawing wood for any other purpose besides block making : We shall therefore take a future opportunity of presenting our readers with these, or at least the most curious among them. See SAWING Machinery.