History of the Jeffrey Mining Corporate Center - State .
A Short History of the Jeffrey Mining Corporate Center. 1876 The Lechner Mining Machine Co. was incorporated to build coal mining machinery. At that time, the slowest part of the mining cycle was the under-cutting, which required a miner to lie on his side for hours at a time, digging out a six inch thick cut, 4 feet deep, across a 10 to 20 foot .