Page:St. Nicholas (serial) (IA stnicholasserial402dodg).pdf/483

charges are always necessary to remove the “cut.” About ten or a dozen sticks were used to each hole. ‘The wires to the detonating caps protruded
WATERPROOFING CONCRETE TROUGH WHICH IS TO CARRY THE AQUEDUCT WATER ACROSS IRONDEQUOIT CREEK. from the holes, and the foreman connected them to a pair of line-wires that ran back to a bulkhead, or strong oaken shelter, about 300 feet away. When everything was ready, the men would hide behind this bulkhead while the boss did the “shooting” by closing an electric switch.

The superintendent thought it a little too dangerous for us to stay there, so we went all the way back to the shaft. As we were on our way, there was a sudden crash that sounded like a pistol-shot directly overhead. Will and I both jumped a yard. We thought the dynamite had exploded. The superintendent only laughed at us.

“That is nothing but the flaking of a piece of rock overhead,” he explained; “you must remember that we are going through rock that was made ages ago, and is under enormous pressure. When we cut a big hole through rock of this kind, the pressure is relieved to some extent, and the rock actually expands into the bore, This

THE DOWN-STREAM FACE OF THE MASONRY PORTION OF THE OLIVE BRIDGE DAM.

movement results in flaking off pieces now and then. We have had flakes weighing all the way from a few ounces to a couple of hundred pounds. When the first pieces flaked off, the workmen were badly frightened, and all stampeded. As I told you before, they are a very superstitious lot. After a while, the reports became so frequent and the fall of stones so dangerous, that we had to do something to protect the men. You see, we have a wooden sheathing just under the roof

Vol. XL.—117