As time went on Smith had more visions until at last the Mormon Church was organized in 1830. Revelations continued. The church grew. Branches were established in various places, but according to their history, the Mormons were persecuted by members of other religious sects and driven from place to place. For a time they were in Kirtland, Ohio. Later they went to Jackson County, Mo., but their houses were burned and they were driven on again. In 1838 "the Lord made known to him (Smith) that Adam had dwelt in America, and that the Garden of Eden was located in Jackson County, Mo." For a time they were in Nauvoo, Ill., where it seems their political activities got them into trouble, and at last Joseph Smith and his brother Hiram were shot and killed by a mob, at Carthage, Ill. That was in 1844. There were then 10,000 Mormons, over whom Brigham Young became the leading power. Soon after this the westward movement began. They established various settlements in Iowa, and in 1847 Young and his pioneer band of 143 men, 3 women and 2 children, entered the valley of Salt Lake, where they immediately set up tents and cabins and began to plow and plant, and where they started what the Mormons say was the first irrigation system in the United States. Certainly there were good engineers among them. Their early buildings show it--especially the famous Tabernacle in the great square they own at the center of the city. The vast arched roof of the Tabernacle is supported by wooden beams which were lashed together, no nails having been used. This building is not beautiful, but is very interesting. It contains among other things a large pipe organ which was, in its day, probably the finest in this country, although there are better organs elsewhere, now. The Mormon Trails are also recognized in the West as the best trails, with the lowest levels, and there are many other evidences of unusual engineering and mechanical skill on the part of the early settlers, including a curious wooden odometer (now in the museum at Salt Lake City) which worked in connection with the wheel of a prairie schooner, and which was marvelously accurate. The revelation as to the practice of polygamy was made to Brigham Young, and was promulgated in Utah in 1852, soon becoming a subject of contention between the Mormons and the Government. The practice was finally suspended by a manifesto issued by President Wilford Woodruff, in 1890, and the "History of the Church," written by Edward H. Anderson, declares that "a plurality of wives is now neither taught nor practised."