Oct. 1, 1864.] THE TECHNOLOGIST. 



WORKING THE BATH FREESTONE. 139 



soundness of the rock. In the Corsham workings, they can, without 

 danger, be driven a width of from twenty-five to thirty-five feet. In the 

 Box quarries, where the rock is not so sound, and the capping bed, 

 before referred to, not so regular, the drivings are limited to from twelve 

 to twenty feet. This is, of course, regulated by the space that may be 

 safely opened without danger to the working beneath. It must be 

 evident that the removal of eight or nine inches of the rock immediately 

 under the ceiling deprives the overlying strata of the support of this 

 area of stone, as effectually as its removal throughout, from roof to floor, 

 would do, and any tendency to settle or drop is at once determined and 

 any risk of life thus guarded against. Another process, by a fresh 

 agency, is now called into exercise, for the cutting of the rock into 

 blocks of required dimensions ; for this, a one-handled saw is used. 

 These saws are worked in lengths of four, five, six, and seven feet, and 

 are made broad, rather I should say, deep, at the head or extreme point, 

 so as to insure the saw sinking to its work at that point. The saw is 

 worked at first horizontally, dropping a little as the cut goes on ; and 

 after the rock is thus opened down to the next natural parting, and the 

 block thus separated laterally from the parent rock, levers are intro- 

 duced into the bed or parting at the bottom of the block, and these 

 levers are weighted and shaken till the block is forcibly detached at the 

 back. It is then drawn down by crane power, and the broken end and 

 the bed dressed with the axe, so as to make the block shapely ; it is 

 then placed on a trolly, and allowed to run to the loading platform. 

 After the first block is removed, it will be evident that the work- 

 men have then access by that opening to the back of the bank of stone, 

 and they avail themselves of this to work the saw transversely, which, 

 separating the block from its back or hinder attachment, renders all 

 further breaking off unnecessary, so the first block of each face is the 

 only stone broken from the rock. To each face or heading of work, a 

 ten-ton crane is erected in such position as to command the whole face. 

 These cranes are now constructed telescopically, so as to accommodate 

 them to slight variations in the headings, arising from differences in the 

 depths of the valuable beds, and the expense otherwise attendant on 

 frequent alteration of the crane is thus avoided, and the periodical shifts 

 from old worked-out to new localities are effected with less trouble and 

 loss of time. Sometimes after a block of freestone has been loosened 

 in situ, a Lewis bolt is let into the face of the block, the chain of the 

 crane attached to it, and the block is then drawn out horizontally. By 

 the removal of the first stratum a sufficient space is obtained to allow 

 the workmen an entrance under the roof ; and vertical cuts are again 

 carried down through the next bed to the parting below, and a transverse 

 cut readily made ; meanwhile, the cutting is continued in the picking 

 bed, the upper layer removed as before, and everything below this point 

 quarried away, with all the sides of the block sawn, except the bed on 

 which it has rested, and those abutting on the natural joints ; hence 



