METHOD OF COMPILING THE MAP. 97 
Lieutenant Parke’s map of his surveys for a railroad route in California, in 1854— 55, has 
also been reduced without change on the general map. The following note appears on his map: 
_‘*The entire coast line, with the exception of that portion lying between Point San Luis and 
Santa Barbara, and also the position of Picacho de Gavilan, were obtained from charts of the 
United States Coast Survey. The eastern limits of the Coast range; the position of the Tulare, 
Buenavista, and Kern lakes; a portion of the Mohave valley; the Los Angeles and San Bernar- 
dino plains; the Santa Ana river; and the foot hills of the Sierra Nevada, were obtained from 
the surveys of the United States General Land Office. The lower portion of the Mohave valley, 
and the south end of Soda lake, were taken from the surveys of Lieutenants A. W. Whipple and 
R. S. Williamson, United States Topographical Engineers.”’ 
The portion of the Coast mountains of California lying between the limits of Lieutenant 
Parke's and the Mexican boundary maps, and the country extending as far east as Soda lake, 
are reduced partly from the Land Office maps, partly from Lieutenant Williamson's map of 
surveys in 1853 and 1854, and partly from Lieutenant Whipple's survey of a railroad route 
near the thirty- fifth parallel. The San Bernardino meridian, placed in longitude 116° 55’ by 
referring it to the Coast Survey longitude of San Diego and San Pedro, is considered to deter- 
mine the longitude of other points where the Land Office surveys have been carried with more 
accuracy than either Lieutenant Whipple’s or Lieutenant Williamson’s surveys. The longitude 
of the eastern entrance of the Cajon Pass is thus fixed at 117° 29’; Lieutenant Whipple having 
it 117° 25’, and Lieutenant Williamson 117° 32 40". Los Angeles is placed in longitude 118° 
14’; being on Lieutenant Whipple’s map 118° 10’, and on Lieutenant Williamson's 118° 13 20". 
The maps of Lieutenants Whipple and Williamson have been altered in the reduction to agree 
with these positions. The mouth of the Mojave cafion, west of Soda lake, is placed by Lieu- 
tenant Whipple in longitude 116° 117 35", and by Lieutenant Williamson in longitude 116° 18’. 
As Lieutenant Whipple had the benefit of Lieutenant Williamson’s determination in making 
his own, and was, moreover, supplied with an astronomical transit, his longitude has been 
adopted. - However, as his longitude of Cajon Pass was 4’ too far east, the same error probably 
affects his location of the point under consideration, and it would, perhaps, be more accurate to 
assume a mean position between Lieutenants Williamson and Whipple’s for the mouth of 
the Mojave cañon, viz: 116° 15’. By taking Lieutenant Whipple’s determination, I was enabled 
E. CNEA his map nen Menge from this point to near its eastern or starting point at Fort 
mith. — 
The longnde of Fort Bait, 7 as determined by the Land Office maps in die 
manner already stated, is 949 25'. "This result receives confirmation from the determination of 
the longitude of Fort Gibson, 95° 15’, by Lieutenant Woodruff. For, by the road survey 
made by R. Richardson in 1826, the difference of longitude between Fort Gibson and Fort 
Smith is 0° 51'; agreeing almost exactly with these two independent locations. The following 
positions in longitude have been given Fort Smith on different maps: 
i [e] Li 
Major Long’s map of explorations to Rocky mountains in 1820. .................... 95 05 
Lieut. Simpson’s survey of Canadian in 1849............. Lee cece es e mirri 94 23 
UD RD Mero map of his routes tti 1849.2... مج همم وم مج‎ RE 94 14 
Map compiled in Topographical Bureau in 1850................ cece ee cece ee eese 94 03 
Capt. Marcy’s map of explorations to sources of Red river in 1852 ................ + 94 0T 
Lieut. Whipple's map of pen for Pacific railroad route in 1853 and 1854...... .... 94 29 
pti Dru ee و‎ e ar esu REG «< < ES < 94 25 
13 
