BUILDING AND ORNAMENTAL STONES. 325 



The illustration shows the drill- rod or spindle placed near the base of 

 the machine, and so as to bore horizontally. At one end of tbe spindle 

 is the drill-head, armed with carbons, and supplied with small aper- 

 tures or outlets for water. At the other end of the spindle is attached 

 a hose for supplying water to the drill- head. A rapid revolving move- 

 ment is communicated to the drill-spindle by the gears shown. The 

 speed and feed movement may be regulated by the operator with refer- 

 ence to the hardness or softness, coarseness or fineness, of the material 

 to be bored ; and the feed movement may be instantly reversed at pleas- 

 ure. The machine is so constructed that the drill-spindle may be re- 



Diamond Gadder. 



moved and another inserted in the same holder, adjusted to bore in the 

 opposite direction, the boring apparatus being driven by a double-cylin- 

 der engine. A continuation of one of the piston-rods through the cylin- 

 der forms the plunger to a small pump placed above the cylinder, which 

 supplies water to the boiler and forces water through the drill spindle 

 and head. These jets of water wash out all the borings made, and keep 

 the drill-head from heating. The usual feed of this drill in marble is 

 from 4 to 5 inches per minute. 



Still another style of gadding-machine isused in the Vermont quarries, 

 and which is but an especial adaptation of the eclipse drill shown on 

 page 326o It is claimed that this machine will "put in holes close to the 



