The different sorts and sizes of blocks used in the yrivy exceed two hundred, and they vary from four to twenty-eight inches in length. Those above eigh teen inches are more sparingly used, and the shells of the largest kinds are made in parts, and fitted to gether by band.
To the completion of this ingenious machinery, Brunell gave his whole attention from the month of September 1802 to June 1808, during which time he received no other compensation beyond the daily allowance of one guinea ; but as it was now in full operation, and ascertained to be capable of making a sufficient number of blocks for the whole naval and ordnance departments, it became a question in what manner the author of the invention should be re warded. It was suggested by General Bentham, and agreed to by Brunell, that the savings of one year, as compared with the contract prices, would be a fair and not an unreasonable remuneration for the time, labour, and ingenuity, bestowed on these extraordi nary machines. It was no easy matter, however, to ascertain with precision what the actual savings amounted to.
Mr Brunell, by estimate, made them amount to L.21,174 0 0 Mr Rogers, clerk to General Ben tham, by estimate 12,742 0 0 General Bentham, after going into every possible details of expence with the utmost minuteness that could be expected in a private manufacturing con cern, calculated them at - L. 16,621 0 0 Add six years' allowance at a gui nea a-day, about 2,400 0 0 For the working-model 1,000 0 0 Total amount received by Brunel, about L.20,000 0 0 Supposing, therefore, the whole cost of the build ings, steam-engine, machinery, interest of money, &c. to amount (which we understand to be about the mark) to L.53,000, and the net compensation for profits to about L. 18,000, the whole expence of the concern was completely cleared in four years. The savings of L. 18,000 on one year's manufactured ar ticles of the value of L. 50,000, amounts to some what more than Brunell had originally made it by computation.
It would occupy too much space to enter into a minute description, and require more time than we can spare, to prepare engravings in detail of the va rious complicated systems Of machinery that are em ployed for the completion of a block ; and, after all, they would afford but little use or instruction, except ing perhaps to a professed machinist ; and perspec tive views of the several systems would tend rather o efildend or confase, than -to info= the general treader. But as weary body who happens to inspect ,
Portsmouth dock-yard, makes a point of visiting the biock-asachinery, we think it may be of same use, in conveying a general ides of the Most striking parts of the machinery, by following the process of making a block from the rough unaided tree, till the last finish is given to it.
We have stated, that the original intention of the building was that of a wood-mill, in which all man ner of sawing, turning, boring, rabbetting, &c. was• to be performed, and that the block-machinery was superadded to the first design, with which, however, it has interfered so little, that, in addition to the im mense number of blocks manufactured at the mill, upwards of a hundred different articles of wood work are made by other machinery—put in motion by the same steam-engine, from the boring of a pump of forty feet in length, to the turning of a button for the knob or handle of a drawer. (See DOCK-YARD, PORTSMOUTH.) Lest, however, the engine, with such a variety of work, might be overloaded, a se cond engine has been added, to assist, if found ne cessary, or to substitute in the event of accident happening to the other. Among the many ingeni ous machines belonging to the wood-mills, exclusive of those for making blocks, one of very great effect, and, at the same time, great simplicity, is a circular saw for cutting rabbets in the edges of deal planks, invented by Mr Burr, the superintending master or the wood-mills.
The whole of the machinery in thele mills is put in motion by straps passing over drum-heads, which the several movements, numerous as they are, are carried on without the least noise ; and all the engine-work, and every part of the machinery, are so truly made, and to firmly put together, and work with such accuracy in all their motions, that, though the spectator is surrounded on all sides with move ments in every possible direction, and some most re pid and violent, the only noise that disturbs him arises from the cutting, boring, turning, polishing, and other instruments which are actually in contact with the work that is under execution, and none of it from the working of the machinery. All the iron work, of which it is chiefly composed, was made by Mawdsley ; and there is but another workman, per haps, in the United Kingdom, who could have finish ed the engines in a raanner so worthy of the invert• tion.