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1920-1929 machines also required less electricity to run. Another consideration favoring AC was greater safety attained in operation. "Should anybody come into contact with the feed line or any part of a live direct-cur- rent circuit, he would be subject to a shock from a current of this potential." Mechanization was addressed again in an August 17, 1922, article titled "Can Mechanical Replace Human Energy in Underground Loading?"—a summary of a series of papers, in particular one read by J.F. Joy, that were presented at a meeting of the Engineers' Society of Western Pennsylvania. At the meeting, Joy broke down the costs involved in loading coal in terms of power required. "The annual production in the United States, which totals more than 500,000,000 tons is loaded at the face by approximately 400,000 miner workers out of the 750,000 employed…this operation absorbs the greater part of the labor employed in the mining of coal. It is said that a man at work will through an eight-hour shift develop 1/10 of a horsepower, so that for 400,000 miners the power equivalent is 40,000 hp. Converting this value to kilowatt- hours and allowing 200 working days per year, the work equivalent resolves itself into 47,744 kW/hr. With a daily wage of $5 it will be seen that the loading process costs the coal industry $400,000,000 per year or $10,000 a year for each horsepower. Similarly the work costs almost $10 per kw/hr or four to five hundred times the cost of electrical energy." Joy and other engineers had, by 1922, been long focused on replacing human power with mechanical. Part of the problem up until then was that the mines were designed and built with only human power in mind. "To make conditions more suit- able to the handling of a particular type of machine the cry has been raised to supplant the room and pillar system by one of the many wall systems." Room-and-pillar, according to Joy was the method used by 98% of the industry at the time, so the ques- tion was also one of adopting the new machines to that format. Unfortunately, the early machines also broke down frequently and were often available less than 50% of the time. The [Joy] Low Model Machine The paths of the fingers are here plainly shown. In this low model the second conveyor serves for a temporary storage place of the hopper used on the higher machine. This will carry when filled with a sufficient amount of coal to appreciable shorten the time necessary to fill a car upon the track behind the machine. *Coal Age, May 6, 1920 By 1924, however, many of these early problems were being worked out and over 20 different kinds of loading machines were in use nationwide. By then, according to J.F. Joy, more than 200 of his company's machines were then in operation nation- wide. The second largest machine produc- er, Myers-Whaley Co. had about 40 machines then in operation as well. "Asked as to the savings affected by the operation of his machines, Mr. Joy said that the only knowledge he had was from an operator in West Virginia who claimed that he could load with his Joy loader at about 30c. per ton less than by handloading…based on the 1920 wage scale." While eastern producers were learning how best to use and develop the new load- ing machines, at the Union Pacific Railroad underground Hanna No. 4 mine, operators were trying to mechanically mine a huge 32 ft seam. Though blessed with good roof conditions, a lack of available timber pre- sented serious challenges. The company turned to large Thew shovels working in conjunction with Joy loaders. They "earned their keep" during the first six months of the year, said Eugene McAuliffe, president of the company in an October 30, 1924, article. Compared to handloading, the Thews saved nearly 28c a ton and the Joys saved 11 ct ton. "Together the saving averaged 25.2c a ton; but it was Mr. McAuliffe's opinion that nei- 50 www.coalage.com 100th Anniversary Special Issue August 2012