Mechanical piston drills utilizing connected bits on drill rods and going up and down similar to a piston inside of a cylinder date from 1843. In Germany in 1853 a drill that resembled modern day air drills was invented. Piston drills ended up superseded by hammer drills operate by compressed https://tax-advantaged-retirement96161.blogcudinti.com/36724698/how-central-bank-policy-can-save-you-time-stress-and-money