I've found  a large number of references online which state that the 
original size of the Erie Canal locks was 90 feet by 15 feet, built to 
accommodate boats of 61 feet by 7 feet.  I can't find a primary source to 
confirm this. Is it true that boats on the original (pre-enlargement) canal 
were limited to 61 by 7 feet, and if so, why, if the locks were 90 by 15 
feet? Thanks.