Editing Comstock Lode (section)

== Innovations and development ==

===Mining===
[[File:Gould & Curry.jpeg|thumb|right|Bonner Shaft, Gould & Curry Mine, 1874]]
The ore was first extracted through surface diggings, but these were quickly exhausted and miners had to tunnel underground to reach ore bodies. Unlike most silver ore deposits, which occur in long thin veins, those of the Comstock Lode occurred in discrete masses often hundreds of feet thick. Sometimes, the ore was so soft it could be removed by [[shovel]]. Although this allowed the ore to be easily excavated, the weakness of the surrounding rock resulted in frequent and deadly cave-ins. The excavations were carried to depths of more than 3,200 feet (1,000 m) (eventually, after years of work).

The cave-in problem was solved by the method of [[Philip Deidesheimer#Square set timbering|square set timbering]] invented by [[Philip Deidesheimer]],<ref name=Smith/>{{rp|23–24}} a German [[mining engineering|mining engineer]] from San Francisco, who had been requested to survey the problem by the owners of the Ophir Mine. Previously, timber sets consisting of vertical members on either side of the diggings (ribs) capped by a third horizontal member to support the back (roof), creating a tunnel (drift). However, the Comstock ore bodies were not veins, but sporadic pockets too large for this method. Instead, as ore was removed it was replaced by timbers set as a cube six feet on a side (ribs), front (face) or top (back), all at the same time. Thus, the ore body would be progressively replaced with a timber lattice. Often these voids (stopes) would be re-filled with waste rock from other diggings after ore removal was complete. By this method of building up squares of framed timbers, an ore body of any width may be safely worked to any height or depth. Deidesheimer was appointed to the Ophir as mine manager for his ingenious idea.

[[File:Carleton Watkins (American - The Bullion Mine, Virginia City, Nevada - Google Art Project.jpg|thumb|left|Bullion Mine, [[Virginia City, Nevada]] {{Circa|1875}}–77]]
Early in the history of Comstock mining, there were heavy flows of water to contend with. This called for pumping machinery and apparatus, and as greater depth was attained, larger pumps were demanded. All the inventive genius of the Pacific Coast was called into play, and this resulted in construction of some of the most powerful and effective steam and hydraulic pumping equipment to be found anywhere in the world. Initially, the water was cold, but the deeper workings cut into parts of the mountain where there were heavy flows of hot water (mines do not always work in digging ore. Some parts of a mining operation could be deepening the existing shaft, or exploring for more ore bodies).<ref name=Smith/>{{rp|45,113}} This water was hot enough to cook an egg or scald a man to death almost instantly. Lives were lost by falling into sumps of this water, which was heated by [[Geothermal activity|geothermal]] pockets. The hot water called for fans, blowers and various kinds of ventilation apparatus, as miners working in heated drifts had to have a supply of cool air.

[[Compressed air]] for running power drills and for driving fans and small hoisting engines was adopted in the Comstock mines.<ref name=Smith/>{{rp|46}} Diamond drills for drilling long distances through solid rock were also in general use, but were discarded for prospecting purposes, being found unreliable. Several new forms of explosives for blasting were also developed.

Great improvements were also made in the hoisting apparatus and cages used to extract ore and transport the miners to their work. As the depth of the diggings increased, the [[hemp]] [[rope]]s used to haul ore to the surface became impractical, as their self-weight became a significant fraction of their tensile strength (breaking weight). After hemp rope, iron chains began to become more common. However, fracture was quick, at around half a millisecond. In 1829 [[Wilhelm Albert (engineer)|Wilhelm Albert]] had studied and reported on the failure of the iron chains and began creating a twisted metal cabling known as Albert Rope. In 1864 [[Andrew Smith Hallidie]] manufactured [[wire rope]]<ref name=Smith/>{{rp|47}} and was heavily involved in building early cable bridges and [[ropeway conveyor]]s; his wire rope went on to be used in San Francisco's famous [[Cable car (railway)|cable car]]s, and was also added to the cable drums in the hoist houses on the Comstock Lode. Another innovation was spring loaded cages. The only way in and out of a shaft mine was in the cage, cabled to the hoist.

All products, men and supplies, as well as recoverable ore, travels up and down the shaft in a cage. When the hemp rope or chains broke, the cage would plummet uncontrolled to the bottom of the shaft, killing its occupants or destroying its load. Cages were open to the front and rear, with I-beams on both sides to support the floor. The outside of the I-beams slid through wooden guides up and down the shaft, top to bottom. Spring loaded cages were designed with two swivel rods at the top of the cage, one each attached to the I-beams through bolts and lifted in the center. The outside of the rods were designed to be wider than the cage with a bulbous, round head at the end, notched with teeth molded into the rods. The weight of the cage being lifted, lifted the rods, released the teeth and tightened the spring, allowing the cage to move freely. If the chain or cable broke, the springs would force the rods down and the teeth would dig into the wood, stopping the cage.

===Processing===
[[File:PSM V49 D771 Alta mine mill and dump on gold hill.jpg|thumb|Alta Mine mill, {{Circa|1896}}]]

In 1859 the Americans knew nothing about silver mining. John D. Winters Jr., and J.A. Osborn built two [[arastra]]s, for the [[patio process]], at the Ophir claim, and Gabriel Maldonado, a Mexican of Spanish descent, "began to smelt some of his rich ore in little adobe furnaces, Mexican fashion", after purchasing Penrod's share of the "Mexican" mine.<ref name=Smith/>{{rp|16}} These methods proved to be too slow for the Americans and could not process the quantities of ore being extracted. The Americans introduced [[stamp mill]]s for crushing the ore, and pans to hasten the process of [[Pan amalgamation|amalgamation]]. Some of the German miners, who had been educated at the [[Technische Universität Bergakademie Freiberg|mining academy of Freiberg]], were regarded as the best then existing to work with [[argentiferous]] ores. 

Bagley introduced a variation of the Freiberg process, using the revolving barrel process of amalgamation, and chloridizing-[[Roasting (metallurgy)|roasting of ores]], after the stamp dry-crushed. While the barrel process was an improvement on the patio, it was found not to be well adapted to the rapid working of the Comstock ores as pan amalgamation. The Comstock eventually developed the [[Washoe process]] of using steam-heated iron pans, which reduced the weeks required by the patio process to hours.<ref name=Smith/>{{rp|41–45,80}}

In the early days of pan processing of ores, there were tremendous losses in precious metals and quicksilver (mercury). Almost every millman was experimenting with some secret process for the amalgamation of ore. They tried all manner of trash, both mineral and vegetable, including concoctions of cedar bark and sagebrush tea. At that time, untold millions in gold, silver and quicksilver were swept away into the rivers with the tailings. The Carson river and the [[Lake Lahontan (reservoir)|Lake Lahontan]] carry warnings against mercury. Although many patterns and forms of amalgamating pans were invented and patented, there was much room for improvement. Improvements were made from time to time, resulting in reductions in losses of metals, but none of the apparatus in use on the Comstock was perfect.