Mechanical piston drills making use of hooked up bits on drill rods and going up and down similar to a piston within a cylinder date from 1843. In Germany in 1853 a drill that resembled modern air drills was invented. Piston drills were superseded by hammer drills run by compressed https://preciousmetalinvestments54062.uzblog.net/monetary-policy-an-overview-50198107