32 



ascending the river. I was accompanied by a steamboat engineer 

 and a party of seven men. The other assistants and empk^yes took 

 the steamer for San Diego, and crossed by land to Fort Yuma, which 

 is on the Colorado, 160 miles above its mouth. 



EXTENT OF EXPLORATIONS. 



The schooner arrived at the mouth of the river on the 2d of De- 

 cember, having been much delayed by calms and head winds. The 

 steamboat was finished and launched on the 30th of the same month, 

 and the ascent of the river was commenced on the day following. I 

 continued up the river for 500 miles, reaching, on the 11th of March, 

 in latitude 36° 06', the mouth of a stream supposed to be the Rio 

 Yirgen, beyond which it was impracticable to proceed in boats. I 

 therefore sent back the steamboat and the hydrographic party to Fort 

 Yuma, and, taking advantage of the permission granted in the in- 

 structions from the department, left the river on the 23d of March, 

 with a pack train, to examine as far as possible the country through 

 which the upper Colorado and its tributaries flow. 



Keeping as near as possible to the river, I traversed the region 

 along the 36th parallel, the greater portion of which had been 

 previously unexplored. Most of the line of the 35th parallel was 

 also visited. Following various lines of examination gradually con- 

 ducting towards the east, I arrived, about the 1st of June, at Albu- 

 querque, on the Rio Grande, the distance accomplished during the 

 land explorations amounting to nearly 900 miles. At Albuquerque 

 the expedition was broken up, a few members of the party still re- 

 tained returning home by the overland route to Fort Leavenworth. 



NAVIGABILITY OF THE COLORADO. 



During the progress of my work upon the navigable portion of the 

 Colorado the water happened to be, according to the evidence of 

 those who had lived in that vicinity for many years, unprecedentedly 

 low. An opportunity was therefore afforded of trying the experiment 

 of steam navigation at the worst stage of the river, and at a time 

 when the difficulties ordinarily to be encountered would be consid- 

 erably magnified. 



The region at the mouth of the Colorado is a flat expanse of mud. 

 The lines of the shore and the channels that afford entrance to ves- 

 sels from the Gulf are shifting and changeable, and bars, shoals, and 

 islands, composed of a semi-fluid mass, are in constant progress of 

 formation and removal. The navigation for thirty miles above is 

 rendered periodically dangerous by the strength and magnitude of 

 the spring tides. These have a rise and fall of from twenty-five to 

 thirty feet, and a flow of extraordinary velocity. The flood is pre- 

 ceded by a "bore," or huge tide wave, from four to seven feet high. 



