n his return. They were placed with the Cocopas by
his direction, an arrangement that better describes the relations of the
steamboat people and the natives than anything that could be said about
them. The fuel used was wood, of which there was great abundance along
the shore, the hard, fine-grained mesquite making a particularly hot
fire. The routine of advance was to place a man with a sounding-pole
at the bow, while Robinson, the pilot, had his post on the deck of the
cabin, but the sounding was more for record purposes than to assist
Robinson, who was usually able to predict exactly when the water would
shoal or deepen. Later, Ives says: "If the ascent of the river is
accomplished, it will be due to his skill and good management." Besides
the ordinary shifting of the sands by the restless, current, there was
another factor occasionally to guard against. This was earthquakes.
Sometimes they might change the depth of water on the lower river in the
twinkling of an eye. On one occasion, a schooner lying in a deep part
was found suddenly aground in three feet of water, with no other warning
than a rumble and a shock. Heintzelman, in one of his reconnoissances,
discovered the adjacent land full of cracks, through which oozed streams
of sulphurous water, mud, and sand, and Diaz, in 1540, came to banks of
"hot ashes" which it was impossible to cross, the whole ground trembling
beneath his feet. At low water, even in the lower reaches of the river,
a boat is liable to run aground often, and has to be backed off to try
her fortune in another place. The bottom, however, is soft, the current
strong, so no harm is done and the rush of water helps to cut the boat
loose. One does not easily comprehend how sensitive a pilot becomes to
every tremor of the hull in this sort of navigation. The quality of the
boat's vibration speaks to his nerves in a distinct language, and the
suck of the wheel emphasises the communication.

The Explorer at length arrived at Yuma. Here the remainder of the
party, including Dr. Newberry, having come across country, joined the
expedition, and further preparations were made for the more difficult
task above. The craft was lightened as far as possible, but at the best
she still drew two and one-half feet, while the timbers bolted to the
bottom were a great detriment, catching on snags and ploughing into the
mud of the shoals. There were twenty-four men to be carried, besides all
the baggage that must be t