nine feet thick, formed by a "Remington lattice truss" of timbers pinned together with wooden pegs. Green rawhide was wrapped around the timbers so that when the rawhide dried it tightened its grip on the pegs. When the roof's structural work was completed, sheeting was applied on the roof, which was then covered with shingles. The interior was lathed and then plastered; the hair of cattle was mixed with the plaster to give it strength. Construction of the Tabernacle began on July 26, 1864, but construction of the roof did not begin until 1865 when all 44 supporting sandstone piers designed by William H. Folsom were in place. Grow rapidly built the roof structure from the center out, but encountered difficulty engineering the semicircular ends of the roof. This difficulty dragged structural work on the roof into fall of 1866 even as other parts of the roof were being shingled. However, Grow finished and shingled the entire roof by the spring of 1867, before the interior of the building was finished. The Tabernacle was first used for the October 1867 conference. The roof has lasted for over a century without any structural problems, though the shingles were replaced with aluminum in 1947. The original benches and columns supporting the balcony were made from the native "white pine" (Engelmann Spruce) that the Mormon pioneers found in the area. Because they wanted to "give their best to the Lord", they hand painted grain on the benches to look like oak and the pillars to resemble marble. During the renovations completed in 2007, the original benches were replaced with new oak pews, and legroom was increased from nine to 14 inches, causing an overall loss of capacity of 1000 seats. The Salt Lake Tabernacle organ has its case positioned at the west end above the choir seats, and is the focal point of the Tabernacle's interior. The original organ was made by Joseph H. Ridges in 1867 and contained 700 pipes. The organ has been rebuilt several times with the total pipe count being 11,623, making the Tabernacle organ one of the largest pipe organs in the world. The current organ is the work of G. Donald Harrison of the Aeolian-Skinner organ company, and was completed in 1948. The organ was renovated and restored in 1989 with a few minor changes and additions. The largest 32-foot display pipes in the façade are made