Nineteenth Annual meeting. 



55 



21. Elevation carried from San Diego over the California Southern Railroad to 

 Waterman by check levels, compares with Southern Pacific elevation from San Fran- 

 cisco +3.684. 



6. Elevation at Deming compares with Southern Pacific elevation, corrected as 

 in No. 3, — 0.062 of a foot. Length of railroad levels, 2,347 miles. 



7. Elevation from Deming carried via Southern Pacific Railroad and Yuma to 

 Port Ysabel compares with mean tide at that point (2.80 —1.79 —0.062) +0.948 of a 

 foot. Length of railroad levels, 1,685 miles. 



8. Elevation at Continental Divide (about 40 miles west of Deming and upon a 

 stretch of 173 miles of unconstructed line) compares with "mean tide" elevation 

 brought from Guaymas, — 3,390 feet. Length of railroad level, 1,657 miles. 



9. Elevation at the Southern Pacific overhead crossing of the A. T. & S. F. R. R. 

 near El Paso compares with the Southern Pacific elevation at the same point ( brought 

 from San Francisco and corrected as in No. 3,) +0.128 of a foot, (from data secured 

 by S. P. R. R. during construction,) and +0.460 of a foot, (from data secured by 

 A. T. & S. F. R. R. four years later.) 



Note. — The A. T. & S. F. determination was merely as a second or double check, and the ditTerence 

 between the two checks (about 4 inches) I attribute to four years' settling of the overhead crossing 

 trestle. For correct results, therefore, I use the first comparison in No. 9, and discard the second. 



10. Elevation at Deming compares with elevation carried from Albuquerque over 

 Atlantic &, Pacific & Southern Pacific railroads via Mojave to Deming (2.04 — 0.062) 

 +1.978 feet. Length of circuit, 1,862 miles. 



11. Elevation at Rincon compares with elevation carried from Rincon via Deming 

 and El Paso crossing back to Rincon, +0.190 of a foot. Length of circuit, 218 miles. 



I had thought I should be doing well if I secured a transcontinental check within 

 10 or even 20 feet, or if I secured a check upon any reliable bench east of the Conti- 

 nental Divide within 10 feet. The first, closest and most reliable check obtained was 

 No. 7; and it was generally looked upon as a remarkable coincidence, if not possibly 

 a "manufactured" check, and I little expected to have it so closely supported by the 

 ten other checks above given. All the old field-note books and profiles were diligently 

 searched for breaks, and all the checks here given are substantiated by documents on 

 file in my office. Summarizing, first those lines which are all rail, or upon which 

 level checks level, and assuming absolute accuracy in the U. S. levels between the 

 Kansas City and Atchison benches, we have the following table of — 



BAIL CIRCUIT CHECKS. 



Next summarizing the checks furnished by the assumption that the mean tides 

 of the two coasts have a common elevation, and that Gardner's Atlantic elevation of 

 Kansas City as above stated is correct, the later levels of the Mississippi River Com- 

 mission and Coast Survey to the contrary notwithstanding, and throwing check No. 8 

 out of the general results on account of the unreliability of 173 miles of unchecked 

 preliminary mountain levels, we have the following table of tide checks: 



