The foregoing illustrations will give a general idea of the manner in which the stone is broken or crushed between strong iron jaws; in all cases a revolving perforated screen is necessary (not shown in the drawings) to separate the stone broken to proper gauge from that which is too large, and also from the spalls or chippings. The Blake’s or “Blake Marsden’s” machines are of various sizes and weights; the following particulars with respect to them, as advertised, may be of use.[35] ------------+----------+---------+---------------+------------- Size of | | | | machine at | Approxi- | | Total weight | mouth, | mate | | of machine | showing what| quanti- | | with wheels, | size of | ty of | Nominal | axles, horse | stone each |road metal| horse- | shafts, auto- | Price of[36] machine will| broken | power |matic screening| machine take. | per hour.|required.|apparatus, etc.| complete. ------------+----------+---------+---------------+------------- inches. | cube | H.P. | tons cwt. qrs.| £ _s._ _d._ | yards. | | | 10 × 8 | 3¹⁄₃ | 3 | 5 6 0 |157 0 0 12 × 8 | 4 | 3 | 5 11 0 |167 0 0 15 × 8 | 5 | 5 | 6 19 0 |200 0 0 15 × 10 | 6 | 6 | 8 5 0 |220 0 0 20 × 10 | 8 | 8 | 10 2 0 |265 0 0 24 × 13 | 12 | 10 | 15 5 0 |390 0 0 24 × 17 | 13 | 14 | 16 2 0 |415 0 0 24 × 19 | 14 | 16 | 19 17 0 |440 0 0 30 × 13 | 14 | 16 | 16 2 0 |440 0 0 ------------+----------+---------+---------------+------------- Mr. Till, the Borough Engineer of Birmingham, speaking of the work done by one of Blake’s machines in 1874, says:[37] “The stone-breaking machine at Holliday Street will break on an average 40 tons of ragstone per day, at a cost, exclusive of wear and tear of machine, of 10¹⁄₂_d._ per ton, but it produces 16 per cent. of dust or fine stone; of the remainder one-fifth has to be rebroken by hand, the whole is very irregular in size and very flaky in comparison with hand-broken stone. The machine is much more efficient in breaking granites or pebbles. It has, however, been found very useful during the last two years, in consequence of the difficulty of obtaining labour.” Mr. Jacob, the Borough Engineer of Barrow in Furness, read an excellent paper on the subject of stone-breaking machinery to the members of the Association of Municipal and Sanitary Engineers, at their meeting in Manchester in 1875,[38] giving a full description of one of Blake’s machines, to which I will refer my readers.