No owner, agent or operator of any coal mine operated by shaft or slope shall place in charge of any engine whereby men are lowered into or hoisted out of the mines any but an experienced, competent and sober person not under eighteen years of age; nor shall such engineer be permitted to operate the hoisting machinery unless he be located in such close proximity to the engine and drum as will enable him to continuously have supervision and control of both engine and drum and no person shall be permitted to ride upon a loaded cage or wagon used for hoisting purposes in any shaft or slope, and in no case shall more than twelve persons ride on any cage or car at any one time nor shall any coal be hoisted out of any mine while persons are descending into such mine, and the number of persons to ascend out of or descend into any mine on one cage shall be determined by the director; the maximum number so fixed shall not be less than four nor more than twelve, nor shall be lowered or hoisted more rapidly than five hundred feet to the minute.