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 Sierra, construction was much easier and faster. Under the direction of construction superintendent James Harvey Strobridge, Central Pacific track-laying crews set a record with of track laid in one day on April 28, 1869. Horace Hamilton Minkler, track foreman for the Central Pacific, laid the last rail and tie before the Last Spike was driven. In order to keep the CPRR's Sierra grade open during the winter months, beginning in 1867, 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 mountainside, thus permitting avalanches to slide over the galleries, some of which extended up the mountainside as much as . 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. Union Pacific construction 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.