The sheaves or shivers would, by this new ma chinery, be made so mathematically true, and so ex act to each other in their thickness and diameters, that every sheave of any particular size would equally fit any shell of the size for which it was intended ; and the inconvenience to which ordinary blocks are liable from the friction of the ropes against one or alternately both of the sides of the mortices, was in tended to be removed, by placing a sheet of metal on the upper part of the mortice, bent to the pro per shape by an engine adapted for the purpose. Brunell also proposed a new form for the clue-line and clue-garnet blocks so as to secure the sails from splitting, by preventing the points of the sails getting into the blocks, which has since been adopted and greatly approved of in the navy.
In the sheaves, instead of the double coak or cogue inserted in two halves, he substituted a mined metal coak of a new and particular form, which will be de .
scribed hereafter,- of increased strength and durabi lity. This coak was to be cast with a precision in moulds, and fitted by an engine with the greatest nicety ; the pins or axes of the sheaves to be of wrought iron, case-hardened and coated with tin, which would preserve the iron from rust in the parts which are not kept free from it by friction ; as it has been found by experience that, however tight the pin be forced into the shells, the water will in sinuate itself and corrode the pin ; when this is the the rust soon extends itself to the parts on which the sheave turns, and renders it unfit for use.
Brunelfs prices, 1 4 5 8 11i 18 Contract prices; 2 3 6 12 6 27 Saving in first cost, 0 6k 2 61 4 se 8 101 These savings, if realized to the full extent, were probably not more important than the increased strength; durability, and facility of working, which have been gained by the adoption of the block-ma chinery.
Those parts of the' machinery which Brunell bad completed in London, under his patent, were transferred Portsmouth, and, in the course of the year 1804, were in operation ; but the increased number of machines, the improvements that suggest ed themselves to the ingenious inventor, the appli cation of other machines for making dead-eyes, trucks, and all manner of block-maker's wares, be sides circular and upright saws, lathes, engines for turning pins, rivetting, polishing, &c. exercised his skill and ingenuity till the year 1808y when he sidered the whole system to be complete in every part, and incapable, so far as he could judge, of farther improvement. From that time to the pre
sent, the block-machinery has been in full and con stant employment, without requiring the least alter ation, and very little repair, beyond the unavoidable tear and wear of engines that are kept in almost constant motion ; and, which is still more extraordi nary, without requiring the aid of the inventor, . though attended only by a few common workmen or labourers; but they are superintended by Mr Burr, the master of the wood-mills who is consider ed as an able and ingenious machinist. The quan tity of blocks of every description, manufactured by the machinery in Portsmouth wood-mills, is more than sufficient for the consumption of the whole navy and the Board of Ordnance, and if pushed to the utmost extent of the works, would also have been sufficient to supply a great part of the shipping em ployed in the transport service.
It may be a matter of some curiosity to know the results of this system of machinery. It is put in motion by a steam-engine of thirty-two horses' power, which, however, is applied to a great variety of other purposes at the same time, wholly independent of the block-machinery. It has been found by cal culation, that four men with the machinery, as it now stands, can complete the shells of as many blocks as fifty men could do by the old method; and that six men will furnish as many sheaves as be fore required sixty ; and that these ten men, in dis placing the labour of one hundred and ten men, can with ease finish in one year from 130,000 to 140,000 blocks' of different sorts and sizes, the total value of which cannot be less than L. 50,000; and this is stated to be the average number which has annually been made from the year 1808, to the conclusion of the war. This number is found to be fully suffi cient for supplying the wear and tear of blocks, not only in the naval, but also in the ordnance depart ment. The consumption, however, must depend on other circumstances besides the number of ships in commission, and will be' ter or less according as ships have been employed on severe or easy service, in a good or bad climate, in fine or rough weather, &c. Nor will the number here stated appear to be enormous, when it is considered what a multitude of blocks are required for a thousand sail of ships, which, at one period of the war, were in commission at the same time. A ship of 74 guns, for instance, requires the following blocks for her equipment : The average number of ships of the line in opus. mission, *ppm:5 is he se been about 100 ; Alum would require 143,000; and allowing the senmeising goo ships and vessels to sequive only twice this number, there would be wanted for the first equip. went of the 1000 ships of war, 429,000 blocks, which, at the ordinary rate of making them at the mills, would require three years in completing.