A further gain is the safety of the system.  The blasting is light and is confined entirely within the holes.  No spalls or fragments are thrown from the bast.

The popular idea that the system is antagonistic to the channeling process is a mistaken one.  There are, of course, some quarries which formerly used channeling machines without this system, but which now do a large part of the work by blasting.  Instances, however, are rare where the system has replaced the channeler.  The two go side by side, and an intelligent use of the new system in most quarries requires a channeling machine.  There are those who may tell of stone that has been destroyed by a blast on the new system, but investigation usually shows that either the work was done by an inexperienced operator, or an effort was made to do too much.

A most interesting illustration of the value of this system, side by side with the channeler, is shown in the northern Ohio sandstone quarries.  A great many channeling machines are in use there, working around the new form of holes, and when used together in an intelligent and careful manner, the stone is quarried more cheaply than by any other process that has yet been devised.

To a limited extent the system has been used in slate.  The difficulty is that most of the slate quarries are in solid ledges, where no free faces or beds exist; but it has been used with success in a slate quarry at Cherryville, Pa., since 1888.  Among notable blasts made by this system are the following:  At the mica schist quarries, at Conshohocken, Pa., a hole 11/2 in. in diameter was drilled in a block which was 27 ft. long, 15 ft. wide and 6 ft. thick.  The blast broke the stone across the “rift,” only 8 oz. of black powder being used.  At the Portland, Conn., quarries a single blast was fired by electricity, 15 holes being drilled with 2 lb. of coarse No.  C powder in each hole, and a rock was removed 110 ft. long, 20 ft. wide and 11 ft. thick, containing 24,200 cu. ft., or about 2,400 tons, the fracture being perfectly straight.  This large mass of stone was moved out about 2 in. without injury to itself or the adjoining rock.

Another blast at Portland removed 3,300 tons a distance of 4 in.  Seventeen holes were drilled, using 2 lb. of powder in each hole, the size of the block being 150 x 20 x 11 ft.  In a Lisbon, O., quarry a block of sandstone 200 ft. long, 28 ft. wide and 15 ft. thick was moved about 1/2 in. by a blast.  This block was also afterward cut up by this system in blocks 6 ft. square.  A sandstone bowlder 70 ft. long, average width 50 ft., average thickness 13 ft., was embedded in the ground to a depth of about 7 ft.  A single hole 8 ft. deep was charged with 20 oz. of powder and the rock was split in a straight line from end to end and entirely to the bottom.  A ledge of sandstone open on its face and two ends, 110 x 13 x 8 ft., was moved by a blast about 3 in. without wasting a particle of rock, 8 holes being used, drilled by three men in just one day, and 15 oz. of powder being used in each hole.  A sandstone ledge, open on the face and end only, 200 x 28 x 15 ft., containing 84,000 cu. ft. stone, was moved 1/2 in. by 25 holes, each containing 1 lb. of powder.