CHAPTER III.
The First Rapid--Horseshoe and Kingfisher Canyons--A Rough Entrance into Red Canyon--Capsize of the _Nell_--The Grave of a Bold Navigator--Discovery of a White Man's Camp--Good-bye to Frank--At the Gate of Lodore.
Prof.now took observations for time and latitude in order to fix with accuracy the geographical location of the camp in Flaming Gorge, and to check the estimates of the topographers as they sighted the various stretches of the river.

It has been found that estimates of this kind are quite accurate and that the variation from exactness is generally the same in[5] the same individual.

Hence one man may underestimate and another may overestimate, but each will always make the same error, and this error can be readily corrected by frequent observations to determine latitude and longitude.

A series of barometrical observations was kept going whether we were on the move or not.

That is, a mercurial barometer was read three times a day, regularly, at seven, at one, and at nine.