[32] 
lb 
cnce of it, is its exposition to the south, by means of which, the canal 
•will be earlier and lon,e;er navigable, and less subject to be seized by 
sudden fiosts in spring and autumn. To extend tite advantages of 
the canal to the inhabitants of the southern shore of the Potomac, it 
will be proper, in the j)rojcct, to trace the works required, in order 
to unite with the canal the tributary streams which join it on that 
side. Those streams might thus contribute to feed the canal, and 
extend the boiefits of its communication. 
From the mouth of Savage river to Georgetown, the Potomac 
bseaks through the several ridges which run parallel to the Allegha- 
nies, and rccei\es tiie tributary streams which run between them, 
from the north and from the south. Wherever the river breaks 
through these ridges, its navigation is interrupted, by falls or rapids. 
The ai't of the engineer must avail itself of these falls, by erecting 
dams at those places, to raise the waters and form reservoirs, that 
may feed the canal. That same art must, also, make the tributary 
streams of that river, contribute to the same purpose, and convey 
into tiie canal the surplus of their waters, and the produce of their 
T alleys. 
In proceeding from west to east, the principal ridges, which are 
tiius biokcn through by the Potomac, are. Will's mountain, Evit*s 
mountain, Rugged mountain, Sidelong iiill. North mountain, South 
mountain, and Cotoctin mountain. The shores are most rugged and 
precipitous, at tiie spots where the river breaks through them; the 
intermediate parts answer to the valleys, which run between these 
vidges — they ate genei-ally flat, and offer a soft and rich soil, per- 
fectly adapted to tl)e purposes of a canal. 
Tiie main falls of the Potomac are at Harper's ferry, where it 
breaks through Elk and South mountains, at the rupture of Rugged 
Mountain; at that of Sidelong hill, the falls of Green spring at the 
rupture of North mountain; the Ilook falls, at the rupture of Cotoc- 
tin mountain; the Seneca falls. Great falls, and Little falls. Besides 
these, it presents, above Harper's ferry, several rapids, whose fall is 
less considerable, and does not deserve a particular notice with re- 
spect to our subject. 
'j'lie tributaries, from the northern bank of the Potomac, whose 
waters miglit feed the canal, are from west to east: Savage river, 
George's creek, Conococheaguc, Antietam creek, Cotoctin creek » 
and the Monocacy river. 
The tributajies. iVom its southern bank, are, the South branch. 
Great and Little Cacapon, and Shenandoah. The waters of the Po- 
tomac do not lise at fixed pesicKis; they generally, however, attain 
their greatest elevation in the months of AL^rch and April, whilst. 
Vroni .June to September, they are at tlieir lowest stage. In tlie dry- 
osl seasons, the higher parts of its ')cd. do not present abo\e 18 inches 
in depth, as in all othei* rivers, the middle j)arts of its cour-se rise 
more than the n])per or lower [;arts. At Cumberland, it rises about 
l-2lcet: at Hancock, '■25 feet: at Wiiliamsport, 30 feet. From thence. 
