210 ISAAC A. HOURWICH 



a day. Comparing this amount of water with the average 

 daily tonnage of the district for one year, we find that 

 28.6 tons of water are raised for every ton of ore raised. 

 Careful estimates of the cost of pumping have been compiled 

 and show that it costs 4 cents to pump each ton of water 

 to the surface. Hence, the cost of pumping referred to the 

 ore makes a charge of $1.14 per ton extracted. 



The extraction of the metals from the ore was in the early 

 period not differentiated from mining. The most natural 

 method which suggested itself to the human nund for dealing 

 with the gold bearing rock was to reduce it to the same state 

 in which the alluvial gold deposits were found and to separate 

 the disseminated particles of gold from the pulverized mass 

 by the familiar method of washing. These primitive methods 

 are still practiced in the uplands of Mexico. 



Amalgamation was the most important discovery in- 

 herited by the American miner from his predecessors. In 

 a few cases the ore was crushed in ordinary mortars. At 

 one mine in Maryland the ore, after being crushed in a mortar, 

 was smelted in the neighboring blacksmith shop. 



A type of mill generally used in the west in the early 

 days of quartz mining was the Mexican arrastra. As late 

 as 1880 arrastras still outnumbered the stamp mills. The 

 arrastra in its simplest form consists of a circular bed of rock 

 from 6 to 10 feet in diameter, with walls of vertical planks, 

 having an upright pivoted post in the center, from which 

 extend 2 or 4 horizontal arms. Stone drags, weighing usually 

 from 200 to 1,000 pounds each, are attached by ropes or 

 chains to the extremities of the arms, and are slowly drawn 

 around by the rotation of the latter. The depth is usually 

 between 18 and 30 inches. The pavement and drags are of 

 the hardest rock conveniently obtainable. The capacity of 

 an arrastra does not exceed 4 tons per day of twenty-four 

 hours, and usually varies from 1 to 2 tons. 



Wooden stamp mills of a very crude type were also 

 known to the Spanish-American miners. A quaint specimen 

 of a homemade stamp mill, fairly representative of its Spanish 

 prototype, was seen at work a few years ago in Georgia. The 

 mine and the mill were worked a few months in the year by 



