Identifier: cassiersmagaz401911newy Title: Cassier's magazine Year: 1891 ( 1890s) Authors: Subjects: Engineering Publisher: New York Cassier Magazine Co. Contributing Library: Smithsonian Libraries Digitizing Sponsor: Smithsonian Libraries

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Text Appearing Before Image: , the shot suffersmore than diamonds, but it is enor-mously cheaper. The spoil is not car-ried to the surface by a return streamof water. Instead, a small amountof water is used and the spoil carriedup a short distance to a part of thedevice known as the calyx. This isan upward extension of the barrelwhich surrounds the short length ofcore. The calyx extension envelopsthe rods and serves as a receptaclefor the spoil. The last may thus bedrawn up to the surface. To securethe core, a little sand or gravel iswashed down the rods, and some ofit finds its wav between the core andthe barrel. Caught between the ro-tating barrel and the stationary core,it operates to wedge the two together.The core is broken off near the root,and may then be drawn up in itsbarrel. It is thought that the diamonddrill is more efficient where there isconsiderable variation in the hard-ness of the rock. The comparativecheapness of the steel shot, however,makes this svstem attractive. The THE CATSKILL AQUEDUCT 34*

Text Appearing After Image: COLD SPRING CUT-AND-COVER WORK. SHOWING CONSTRUCTION OF INVERT truth as to the comparative value ofthe two procedures is probably this—one is better adapted for certain workand certain conditions than the other,and vice versa; and both are equallysuited for still other work and otherconditions. As an example of diffi-culties with which the shot drillseemed unable to cope may be men-tioned certain work connected withthe exploratory operations on theEsopus division. There is a bed ofShawangunk grit having a thickness of about 250 feet. This grit is aconglomerate of pure quartz, and ex-ceedingly hard. The drill was ableto cut the rock. That is not wherethe apparently insuperable difficultylay. There are numbers of seams, insome of which there is runningwater. When the drill would reachsuch a seam the shot would be car-ried off and the grinding effectstopped. Manifestly the diamonddrill is the preferable apparatus forsuch conditions. However, if a large 342 CASSIERS MAGAZINE sized hole

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