Labor.-An improvement in the condition of miners is indicated by the government report of 3.54 fatal accidents per 1,000 men in 1913, 3.91 per 1,000 in 1912, and 4.19 per 1,000 in 1911. The big mines and many smaller ones are devoting attention to the "safety-first" movement, and are also inaugurating systems of bonuses, annuities and pensions. The strike of the Lake Superior copper miners ended in failure (see XVI, Labor), and that of the coal miners in Colorado, with its attendant martial law and loss of life, was ended by vote of the strikers in December (see XVI, Labor). Both strikes were claimed by the mine operators to be due to attempts to unionize the men. An interesting struggle in progress is that between rival unions in Butte. The result of the conflict so far has been to cause the operators to open the mines of the district to both union and non-union labor alike.

Government Lands.-Congress has finally passed a bill which will allow the rich coal lands of Alaska to be opened up under competitive bidding for leases in blocks of 40 acres or multiples of that amount. These leases are on a royalty basis of at least two cents per ton and are to run not more than 50 years. Oil, phosphate and potash lands which have been withdrawn from entry by the Government are still awaiting the passage of a bill to allow them to be opened up and put to use. (See also I, American History; VIII, Alaska; X, Public Lands).

Ore Dressing. In ore dressing the problem of saving values in tailings which now go to waste is receiving the most attention. Oil flotation methods are hailed as offering the most promising results, but in the case of copper ores, leaching is also found to be a satisfactory adjunct. Oil flotation has been successfully applied to the lead tailings in southeast Missouri, and experimental work is under way in the zinc district of southwest Missouri. The 600-ton experimental plant of the Inspiration Copper Co. is reported to be working satisfactorily on low grade "porphyry copper" ore and a large mill is in progress of construction. In fact everywhere oil flotation is being in

vestigated for treating original ores, for recovering extra values from tailings, or for enriching concentrates. The legal atmosphere of the oil flotation process has been somewhat cleared by a higher court decision in favor of Hyde against the Minerals Separation Co. (See also Zinc, infra). Wet concentration of iron ores in the Mesabi district is on the increase and is being extended to the Cyuna district. A new process of separation, using a heavy solution of antimony bromide, is being tried out on iron ore at Rich Patch, Va. The first unit of 1,500 tons of the big Alaska Gold Company's stamp mill near Juneau, Alaska, will start early in 1915, and it is expected that the whole 6,000-ton plant will be in complete running order by June 1, 1915.

Prof. R. H. Richards visited various districts during the year, and summarizes important developments as follows: Lake Superior copper district, tendency to finer grinding, leaching of tailings, new White Pine 1,000-ton mill saving very fine copper which could not be recovered by old methods; Butte copper district, improved classification, new 20-deck round table with rough surface, Laist leaching process for tailings, new oil flotation plants for zinc ores of Timber Butte mill and Butte and Superior mill, experimental flotation work at Anaconda; Cœur d'Alene lead district of Idaho, National and Hercules mills using Callow flotation process, Wyman mill using Callow-Wyman flotation, other mills experimenting on flotation, new Bunker Hill and Sullivan mill with latest ideas of construction; Ely, Nev., flotation experiments on porphyry copper ore; Garfield, Utah, experiments on enriching low-grade copper concentrates by flotation. As an illustration of advances in ore dressing, the Anaconda Copper Co. formerly saved only about 75 per cent. of the copper. Now, by additional apparatus, including Dorr settlers, 20-deck round tables, Oliver filters, and leaching of both sand and slime, the extraction of copper will reach 95 per cent. and the waste tailings will contain only 0.1 to 0.2 per cent. of copper. (See also Gold and Silver, infra.)

Coal Mining Machines. The practice of coal mining is still far from being as well systematized as that of other industries. Instead of concentration of work, the operation is still spread over a large area, with a few men working here and there and a small output per man employed. We have underground nothing resembling a steam shovel in operative capacity, no gang work as in railroading, no intensive operation as in a factory. Wherever the several acts of extraction are performed by different men, the work is not continuous; there are long waits between undercutting and shooting of coal, others between shooting and loading and a further wait between loading and transportation.

Till E. O'Toole introduced his mining machine and pneumatic transportation for such coal as is being mined for conversion into coke, all previous attempts at mining the whole coal from floor to roof had been restricted to the heading machines of various kinds which excavated a narrow entry into the coal, speed of progress rather than weight of mineral being the desideratum. During 1913 H. A. Kuhn and H. K. Knopf have been trying to mine and load lump coal by a nearly continuous operation, the coal being hauled out by mule, locomotive or rope in the accepted manner. Their machine mines and drills the coal. It is then shot down and the shoveling conveyor, which is part of the same machine, loads it into

cars.

The Jeffrey entry machine undercuts and shears the coal vertically at one operation, knocks down the coal and loads it into the mine wagons. It is only, as indeed the name implies, intended for narrow work, but it could well be adapted to either a room or a longwall face. Another machine for entry work devised by the Ingersoll-Rand Co. uses a compressed-air punching machine for the cutting of the coal. This is not held to the face by man power, as such cutters usually are, but by the weight of the machine frame. The puncher is moved forward on slides and given a side

wise motion by an auxiliary engine. It undercuts the coal like an ordinary puncher machine and then shears first one side and then the other side of the entry. Finally the conveyor is moved under the cut of coal and the coal is dug down with violent blows from the cutter. As in the other machines mentioned, the coal is delivered by an elevator to a mine car in the rear.

All these machines are indications of a revolution in coal-mining methods; but the last two and the first presage possibly a return to the former method of mining without the use of powder. The shoveling device apart from the punching, undercutting and shearing features is not new and, in fact, there is nothing particularly original except the combination of the many devices in one machine. This, however, is an assurance that the assembled device is practical in its details, even if time is needed to arrange a complete coordination of parts. In some mines shoveling by hand is supplemented by machine loading, the coal being shoveled in an elevator, which passes the material upward and forward into a car.

Mine Locomotives.-The increased use of storage-battery locomotives is significant. The difficulty in the past has been to produce a fool-proof battery. It appears now that all difficulties have been fully met except first cost, and many users believe this objection is not borne out by experi

ence.

Prevention of Mine Explosions.— Further inquiries have been made by the Federal Bureau of Mines into the immunization of mines to explosions by the use of stone dust. The French method of stopping explosions by placing shelves loaded with powdered rock across mine entries, named after its discoverer, Taffanel, was discovered to be most effective when these phenomena were most violent. No opportunity was given in this country for a practical test of its value because the system was not adopted except in a few mines in Colorado, and there the plan used was