<P> To carve a tunnel, one worker held a rock drill on the granite face while one to two other workers swung eighteen - pound sledgehammers to sequentially hit the drill which slowly advanced into the rock . Once the hole was about 10 inches (25 cm) deep, it would be filled with black powder, a fuse set and then ignited from a safe distance . Nitroglycerin, which had been invented less than two decades before the construction of the first transcontinental railroad, was used in relatively large quantities during its construction . This was especially true on the Central Pacific Railroad, which owned its own nitroglycerin plant to ensure it had a steady supply of the volatile explosive . This plant was operated by Chinese laborers as they were willing workers even under the most trying and dangerous of conditions . </P> <P> However, Chinese laborers did far more than mix the volatile ingredients of nitroglycerin for the Central Pacific . Their hard work was also crucial in the construction of 15 tunnels along the railroad's line through the Sierra Nevada mountains . These tunnels were about 32 feet (10 m) high and 16 feet (5 m) wide . When tunnels with vertical shafts were dug to increase construction speed, and tunneling began in the middle of the tunnel, at first hand - powered derricks were used to help remove loose rocks up the vertical shafts . These derricks were later replaced with steam hoists as work progressed . By using vertical shafts, four faces of the tunnel could be worked at the same time, two in the middle and one at each end . The average daily progress in some tunnels was only 0.85 feet (26 cm) a day per face, which was very slow, or 1.18 feet (36 cm) daily according to historian George Kraus . J.O. Wilder, a Central Pacific - Southern Pacific employee, commented that "The Chinese were as steady, hard - working a set of men as could be found . With the exception of a few whites at the west end of Tunnel No. 6, the laboring force was entirely composed of Chinamen with white foremen and a "boss / translator". A single foreman (often Irish) with a gang of 30 to 40 Chinese men generally constituted the force at work at each end of a tunnel; of these, 12 to 15 men worked on the heading, and the rest on the bottom, removing blasted material . When a gang was small or the men were needed elsewhere, the bottoms were worked with fewer men or stopped so as to keep the headings going ." The laborers usually worked three shifts of 8 hours each per day, while the foremen worked in two shifts of 12 hours each, managing the laborers . Once out of the Sierras, construction was much easier and faster . Horace Hamilton Minkler, track foreman for the Central Pacific, laid the last rail and tie before the Last Spike was driven . </P> <P> In order to keep the CPRR's Sierra grade open during the winter months, beginning in 1867, 37 miles of massive wooden snow sheds and galleries were built between Blue Cañon and Truckee, covering cuts and other points where there was danger of avalanches . 2,500 men and six material trains were employed in this work, which was completed in 1869 . The sheds were built with two sides and a steep peaked roof, mostly of locally cut hewn timber and round logs. Snow galleries had one side and a roof that sloped upward until it met the mountain side, thus permitting avalanches to slide over the galleries, some of which extended up the mountainside as much as two hundred feet (60 m). Masonry walls such as the "Chinese Walls" at Donner Summit were built across canyons to prevent avalanches from striking the side of the vulnerable wooden construction . A few concrete sheds (mostly at crossovers) are still in use today . </P> <P> The major investor in the Union Pacific was Thomas Clark Durant, who had made his stake money by smuggling Confederate cotton with the aid of Grenville M. Dodge . Durant chose routes that would favor places where he held land, and he announced connections to other lines at times that suited his share dealings . He paid an associate to submit the construction bid to another company he controlled, Crédit Mobilier, manipulating the finances and government subsidies and making himself another fortune . Durant hired Dodge as chief engineer and Jack Casement as construction boss . </P>

When was the first serious proposal for building a transcontinental railroad