mouth of the river, ran up the wrong channel, struck a sand bar, and was left hanging in a precarious position. Troops were rushed to the scene of the accident to discharge the cargo, as it was feared that she might break up. Meanwhile Captain Johnson returned to San Francisco for additional supplies and the necessary parts to repair the damaged General Jesup. At the fort the explosion proved a serious drawback, and for a second time wagon supply trains were dispatched from San Diego to provision the garrison. By December the damage was repaired, and the steamer was again running regularly to the mouth of the river from Yuma.^*
With the successful operation of the General Jesup, steam navigation on the Colorado became an established fact. However, the real test to determine whether trade could be carried on profitably over a period of time still had to be made. The Johnson Company was determined to make a success of the venture and began the construction of a third river steamer, the Colorado. Her hull was laid in San Francisco, but she was taken to the mouth of the river to be completed and to have her machinery installed.^^ She was longer than either of the first two steamers, being 1 20 feet, and was much more powerful. The most important revolution in her design, however, was the stern-wheel, which had been recommended four years earlier by Lieutenant Derby. Tests soon proved that to operate efficiently in narrow channels, through shallow water or for cutting through sand bars, the stern- wheel was indispensable. The Colorado began operating in December 1855, as evidenced by the following comment from Yuma on the fourteenth of that month: "The express rider informs us that the new steamer Colorado . . . had been completed and had arrived at the Fort. She is said to be a fine boat, and well adapted for the navigation of that river."^®
Within five years after steamboats had been successfully introduced on the Colorado, substantial progress had been made in developing steam navigation both to the mouth of the river and upstream. The opening of the ocean route from San Francisco to the river's mouth was greatly furthered by United States naval vessels ordered to the Colorado with supplies for the Yuma garrison.
A check of these vessels engaged in the ocean trade includes the U. S. schooners Invincible, Capacity, Monterey, General Patterson, and Humboldt, the U. S. transport ship Sierra Nevada, and the brig General Viel, all operating before the end of 1855. In that year privately owned vessels, at least three in number, began commercial activity." The naval vessels, however, did not cease operation immediately. The schooner Patterson ran until 1857; the Monterey until 1858; the Floyd made trips in 1859 and 1860; and the General Jesup carried on from 1862 to 1865.^^ On the river itself two steamers, General Jesup and Colorado, made regular runs from Fort Yuma to the mouth,^^ where they customarily awaited the arrival of the oceangoing vessels. When the latter arrived, they cast anchor in mid-channel and
