20 F 2 . REPORT OF PROGRESS. K. W. CLAYPOLE. 



The canals and pools along the Susquehanna, however. 

 determine its real rate of descent as follows : 



A. Locks. B. Miles. C. Feet. 



Mahantango lock, 35.6 410.97 



Dry Saw-Mill lock, 33.8 403.32 



Liverpool upper lock, 30.8 397.92 



Liverpool lower lock, 29.0 391.49 



Mt. Patrick lock, 26.4 384.57 



Montgomery lock, 24.7 377.75 



Buffalo lock, 21.6 370. 10 



Juniata Junction lock, . . . • 17.0 370.35 



Raisner's lock, — 362.09 



Clark's Ferry guard-lock, 15.0 356.09 



Twin Tavern lock, 12.0 343.09 



Dauphin lock, 7.7 336.29 



Rockville lock, 5.1 329.30 



Harrisburg lock, 0.0 322.39 



A is the tabular list of locks descending the river. 



B gives the distance, in miles, from Harrisburg. 



C gives the elevation above tide of the water in the clam 

 above each lock, infect, according to Allen and Ames' sur- 

 vey. 1877. as explained in the prefatory note to table 115, 

 page 120, of Report of Progress N. 



From Mahantango,at the northeast corner of Perry county, 

 to Rockville, at the southeast corner of the county, a dis- 

 tance of 30£ miles, the Susquehanna river has a total fall of 

 8H feet, or at the rate of about 2f feet per mile. 



Rate 



From. To. Miles. Fall, per mile, 



Mahantango— Dry Saw-Mill, 1.8 7.65' 4.25' 



Dry Saw-Mill-Liverpool U. L., .... 3.0 5.40' 1.80' 



Liverpool U. L.— Liverpool L. L., ... 1.8 6.43' 3.57' 



Liverpool L. L.— Mt. Patrick, 2.6 6.92' 2.66' 



Mt. Patrick— Montgomery, 1.7 6.82' 4.01' 



Montgomery— Buffalo, 3.1 7.65' 2.47' 



Buffalo— Juniata Junction, 4.6 0.00' 0.00' 



Juniata Junction— Clark's Ferry, .... 2.0 14.26' 7.13' 



Clark's Ferry— Twin Tavern, 3.0 3.00' 1.00' 



Twin Tavern-Dauphin, 4.3 6.80' 1.58' 



Dauphin— Rockville, 2.6 6.99' 2.69' 



Rockville-Harrisburg, 5.1 6.91' 1.35' 



The Susquehanna river, then, descends with comparative 

 rapidity where it passes through the five gaps of Buffalo, 

 Berry's, Peters', Second, and North mountains, and less 



