204 

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well enough determined independently, were connected with different 

 points in the main lines. In the central line we have the following 

 parts : From Mount Wilson to station 30, a peak east of it and distant 

 9.3 miles, is a fall of 383 feet, which is the mean of five determinations 

 having a range of 32 feet ; thence east to Sultan Mountain, a distance of 

 6.88 miles, with a fall of 536 feet, the mean of sis determinations, range 

 23 feet ; thence northeast to station 16, distant 6.60 miles, a rise of 17 5 

 feet, the mean of nine determinations, range 35 feet ; thence northeast 

 to Handle's Peak, 7.51 miles, a rise of 456 feet, the mean of eight deter- 

 minations, range 54 feet; thence north to Uncompahgre Peak, distant 

 11.14 miles, a rise of 238 feet, the mean of nine determinations, range 

 49 feet ; thence east to station 8, distant 4.92 miles, a fall of 1,380 feet,, 

 the mean of ten determinations, range 67 feet. This completes the cen- 

 tral or trunk line, whose length is 46.35 miles. From Sultan Mountain 

 a branch was extended eastward ; from this peak to station 25, distant 

 10.28 miles, a rise of 209 feet, the mean of twelve determinations, range 

 67 ; thence to Rio Grande pyramid, distant 8.63 miles, arise of 197 feet,, 

 the mean of nineteen determinations, range 95. 



From station 25, a branch extends to Mount Oso, distant 7.29 miles,, 

 a rise of 64 feet, the mean of seven determinations, range 37. 



From station 30 a secondary branch was extended south and west. 



Station 30 to Engineer Mountain, distant 0.98 miles, a fall of 926 feet^ 

 the mean of eight determinations, range 22 ; thence west to station 36',. 

 distant 6.76 miles, a fall of 417 feet, the mean of eleven determinations,, 

 range 51 ; thence to station 37, distant 3.65 miles, a rise of 94 feet, the 

 mean of five determinations, range 35. 



Another important subline extends from Sultan Mountain to the 

 northwest. The first link in the chain is the line from this point ta 

 station 28. The heights of stations 30 and 16,- above Sultan Mountain, 

 having been already well determined from the central chain, I made use 

 of all the connections between station 28, and each of these points, re- 

 ducing all of them to a common point. The result from this was the 

 following : Sultan Mountain to station 28, distant 7.86 miles, a fall of 

 484 feet, the mean of eighteen determinations, range 76 feet ; thence to 

 station 29, distant 3.77 miles, a rise of 324 feet, the mean of eight de- 

 terminations, range 43 feet ; thence to Mount Sneffels, distant 5.94 

 miles, a rise of 952 feet, the mean of six determinations, range 36 feet ; 

 thence to station 34, distant 6.65 miles, a fall of 1,161 feet, the mean of 

 five determinations, range 23 feet. 



This completes all the well determined chains. Other stations on 

 which barometric readings had been taken, were connected with as 

 many points in the main lines as possible, and these being reduced to a 

 common point a mean was taken. Such points are the following : 

 Sultan Mountain to station 10, a fall of 223 feet, the mean of eleven 

 determinations, range 76 feet; Uncompahgre Peak to station 5, a fall of 

 1,498 feet, the mean of ten determinations, range 85 feet. Uncompah- 

 gre Peak to station 11, a fall of 3,624 feet, the mean of eight deter- 

 minations, range 111 feet; Sultan Mountain to station. 51, a fall of 835 

 feet, the mean of three determinations, range 75 feet ; Sultan Mountain 

 to station 48, a fall of 1,061 feet, the mean of six determinations, range 

 59 feet; Handle's Peak to station 13, a fall of 1,175 feet, mean of fore 

 and back sights, range 6 feet. 



Besides these there are two which depend on single determinations : 

 First from Sultan Mountain to the point in Baker's Park where the road 

 crosses Cement Creek in Silverton, distant three miles, a fall of 

 3,961 feet. Second, from Mount Sneffels to station 32, which is obtainec;! 

 from sights to a common point between them, distant from Mount 



