BORING 



445 



The boring rods are of the best steel, and jointed together by unions or coupling 

 boxes. 



In soft strata it is somewhat difficult to obtain a core by the diamond borer, but in 

 boring through hard rocks for which this machine is specially suitable a very perfect 

 core is produced. The best average speed accomplished by this machine in hard rock 

 equals about 50 feet per day of 12 hours. 



Mather and Plait's System of Boring. The Chinese method of boring with ropes, 

 instead of rigid rods, has been tried at different times in Europe, but without any 

 great amount of success ; the system of rigid suspension being preferred for working, 

 not only the cutting tool, but also the shell. A very important modification of this 

 principle has, however been introduced by Messrs. Mather and Platt of Salford, who 

 have succeeded in carrying bores of considerable size (8 or 10 inches in diameter) to 

 depths of 1,200 feet and upwards. 



In this system, instead of the implements being attached to rods, as in the previous 

 systems, they are suspended by a flat hemp rope about inch thick and 4J inches 

 broad, such as is commonly used at collieries, and the boring tool and shell pump are 

 raised and lowered as quickly in the borehole as the cages in a colliery shaft. 



The flat rope A A, fig. 183, from which the boring head sis suspended, is wound upon 



183 



a large drum c, driven by a steam-engine D with a reversing motion, so that one man 

 can regulate the operation with the greatest ease. All the working parts are fitted 

 into a wood or iron framing E, rendering the whole a compact and complete machine. 

 On leaving the drum c, the rope passes under a guide pulley F, and then over a large 

 pulley o, carried in a fork at the top of the piston-rod of a vertical single-acting 

 steam-cylinder H. 



This cylinder, by which the percussive action of the boring head is produced, is 

 fitted with a piston of 15 inches diameter, having a heavy cast iron rod 7 inches 

 square, which is made with a fork at the top carrying a flanged pulley. 



The boring head having been lowered by the winding drum to the bottom of the 

 borehole, the rope is fixed securely at that length by the clamp J ; steam is then ad- 

 mitted underneath the piston in the cylinder H by the steam-valve, and the boring 

 tool is lifted by the ascent of the piston-rod and pulley a ; and on arriving at the top 



