100 METHOD OF COMPILING THE MAP, 
and I have adopted the latter, thinking it most probable that the discrepancy grew out of error 
in copying the manuscript or printing the report. I have made out the following list of 
latitudes and longitudes from the report, though it is not always certain that they are given as 
the result of astronomical observation. 
Place. dont. Latitude. Longitude. 
۱ o rt» gu v 
Mouth of Big Witchita, (on the map 349 15/) 34 25 1 S | 
Camp on Otter Creek ; |. 84. 34 16 100 00 45 
Camp on North Fork, Red river ES 35 03 00 100 12 ۰ 0 
Do do do ; | 85.15.45 
Do. do do 1 35 24 50 > 
Camp on Sweetwater creek i 56 $6 18 22 ۱ 
Camp on North Fork, near the source — 35 35 03 101 55 00 
Camp near Red river and Panther pond, (on map 34€ 38) : 34 08 39 |. i 
Camp on Gypsum creek, (on map 34° 38’) S4-:08 1 با‎ 
The longitude of the camp on Otter creek was found by lunar distances to be 100° 00’ 45”. 
It is not stated how many observations were taken, but the expedition arrived at the point 
May 22, and by May 29 the observations had been made and calculated, and Captain McClellan 
started on this day, traced the 100th meridian south to its intersection with Red river, and 
marked a cotton-wood tree to indicate the point. The longitude of the mouth of the Little 
Witchita, 98°, and of Fort Washita, 96° 38’, I have already determined, the difference being 
1° 22’. On Captain Marcy’s map of 1852, the first is in longitude 98° 30’, (30' too far west, ) 
and the second is 96° 20’, (18' too far east,) the difference being 2° 10. Fort Arbuckle is 
placed by Captain Marcy in longitude 97° 07’. The position it assumes, by reducing Captain 
Marcy's trail between the mouth of the Little Witchita and Fort Washita to the general map, 
is 97° 08’, and this has been adopted. If the longitudes I have adopted for Fort Washita, 
Fort Arbukle, and the mouth of the Little Witchita are correct, Captain Marcy’s map of 
1852 contains a relative error between the two last points of 30’ of longitude. ` Captain 
Marcy, in his map of 1849, places the mouth of the Little Witchita in longitude 97° 25’, 
and in the one of 1852 in longitude 98° 30’. When at or near the head of the north fork of 
Red river, he made an excursion of about thirty miies direct to the Canadian river, striking it 
at the mouth of Sandy creek, where he marked a tree, in longitude 101° 55’, according to 
his map. Lieutenant Whipple’s exploring party, in 1853, did not know of this, and it is 
not positively certain that the creek, called by Lieutenant Whipple White Sandy creek, 
is that visited by Captain Marcy. If, however, it is the same, its longitude, according to - 
Lieutenant Whipple, is 101° 35’, being 20’ east of the position given it by Captain Marcy. 
This and other reasons lead me to think that Captain. Marcy’s map places the eastern front of 
the Llano Estacado and the sources of ‘the Red river at least 20’ too far west ; for, if Captain 
Marcy’s latitudes be assumed correct, as I have done, and his position of the source of the 
north fork of the Red river be plotted, it falls in the immediate valley of the Canadian, as 
determined hy Lieutenant Whipple, and only about ten miles from the main stream, instead of 
thirty, which Captain Marcy found to be the case. The only way to preserve this distance 
between the streams, without changing the latitudes, is to move the positions of Captain 
