35 [ 32 ] 
there will remain 11 miles 1158 yaitls, or about 11| miles. If we 
subtract it from the length of the Youghiogcny route. (50 miles 1172 
yards,) there will remain 20 miles 1580 yards, or about 21 miles. 
These portions, on either of these routes, may be designated as their 
summit levels. On the Yonghiogeny route, this portion might, per- 
haps, be dropped below the rescrv<*irs of tlie Youghiogeny; but its 
length and expanse of water, which is our present object, wouhl re- 
main the same on either level. We should now examine, fu'rit, what 
means exist to feed thes^ summit levels; second, what eacii of these 
requires to s'upply all its wants and losses; third, what are the respect- 
ive advantages of the one and the othei', and which is the most ad- 
vantageous with respect to tliat question. 
The Great and Little Youghiogeny and their upper tributaries, arc 
the only streams of any importance which can feed either of these 
summit levels. Their levels, with respect to tiie base mark, and at 
diiferent j)oints, areas follow: 
Level of the Great Yougliiogeny, at the mouth of Deep Creek, ft. 
below the base mark - - - - 250. 
Do. at the htxid of Swallow Falls, do. - 140.81 
Do. one mile above the mojjlh of Indian Run, do. 70.50 
Do. two miles do. do. G4. 
Do. at the mouth of the Little Youghiogeny, do, 53. 
Do. at the mouth of Snow Creek, two miles above the 
bridge, do. - - - - - S6 09 
Do. at Charles Glade's run, do. - - 28.72 
Do. at the month of Cherry tree Creek, do. - 26.18 
Level of the Little Youghiogeny, ^where it is crossed by the 
state road, do. - - - - - 44. 
These levels being all below the base-maik, proved, that, whichev- 
er summit level we adopt, we must elevate the waters of the two 
Youghiogeiues, by throwing great dams across them. The licightof 
these dams would be lower, and a less quantity of lockage required, if 
we dropped the summit level of tlje Youghiogeny route; but the length 
of the tunnel from Crabby's arm, and deep cutting at each of its ex- 
tremities, would then be ])i'oportionably augmented. For the sake of 
comparison, we have thei'efore supposed those two routes on a level, 
a ])assage was sought to open a communication between Dqcp Creek 
and the great Yougliiogeny, through the opposite valleys gf Indian 
run and Cranberry run. But, as the sources of these runs rise 226 
feet above the base-mai'k, and the Youghiugheny at the Indian run 
lies 70.50 feet below it, a dam across the Yoghiogheny, and a tunnel 
through the Roman Nose ridge, would both be indispensably required 
to accomplish this object. 
An attempt was also made to lead Muddy Creek, which, from the 
west, falls in the Youghiogheny, to the summit level of Uicse routes. 
But to lead it to the summit level of the Deep Crtvek route, it would 
be necessary to conduct it by alongaqueduct upv\iai'ds of 140 feet high, 
and to lead it to that of the Youghiogheny, to run a feeder upwards 
of SO miles, before it reached the mouth of Indian run, and which 
would absorb, by filfrations and evaporation^ during its course, most 
