“ After absorbing the Gila the river sweeps round in a W. direction for 7 or 8 miles, and soon expands to a width of 1,200 feet. Thence it pursues a tortuous course of 180 miles, the last portion being through Mexican territory to its mouth in the Gulf of California. From the sources of the Green river the Colorado measures a total length of about 2,000 miles. It is navigable for steamers as far as Callville, 612 miles from its mouth, and can be made navigable, it is thought, to the foot of the Grand Cañon, 57 miles higher. ”