the United States of America. 12& 



of water it would rank in a high place among European rivers, 

 the nature of the country is such, that interruptions of a similar 

 character are frequent throughout its whole course. As many 

 parts of the river are bold and deep, the Schuylkill navigation 

 has been effected by using the bed in such places, and con- 

 necting them by canals and lateral cuts. To deepen the river 

 and check its current, twenty-eight wears have been thrown 

 across it. The whole navigation amounts to 108 miles, 46 of^ 

 which lie in the ancient bed of the river, and the remaining 62 

 in the artificial channels. Besides 28 guard-locks at the 

 wears, there are 92 locks overcoming a fall of 588 feet. So 

 that this comparatively short navigation has a greater change 

 of level than the Erie canal of the state of New York. The 

 grand object of this navigation was to form a water communi- 

 cation with a vast coal field, of which we shall have occasion 

 to speak hereafter. 



At a distance of 58 miles from Philadelphia (measured on 

 the Schuylkill navigation,) is situated the borough of Reading. 

 From this a canal, called the Unioriy has been completed to the 

 Susquehannah river. It is 71 miles in length. The summit 

 level is 300 feet above the Schuylkill, and 210 feet above the 

 Susquehannah. In the plan of the canal a difficulty was found 

 in obtaining a supply of water for the summit level. This has 

 been obviated by raising the waters of the Swatura by 

 machinery, at such seasons as the other sources are usually 

 scanty, and this will no doubt be effectual. 



An important improvement in the structure of the locks of 

 this canal was planned and carried into effect, by the very 

 intelligent and skilful engineer (Mr. C. White) who super- 

 intended its construction. This improvement consists in the 

 suppression of the breast wall, and making the upper gate 

 nearly of the same depth as the lower one. The bottom of the 

 lock has a slight slope, and the upper reach of the canal is 

 gradually deepened until its bottom reaches the same level as 

 that of the lower. As the breast wall is the weakest part of a 

 lock, and adds considerably to the expense of construction, 

 while it involves, in addition, the cost and inconvenience of 

 lateral culverts in the walls, this improvement may be con- 

 sidered as very important ; it is, in truth, the only change of 



