40 
GEOLOGY OF NORTH CAROLINA. 
Area 
u 
subeast’n, reg’n 9,000 “ “ 
a 
200 
u 
middle i: 12,000 “ “ 
a 
650 
U 
u 
a 
piedmont “ 6,000 “ “ 
a 
1,000 
a 
u 
u 
mountain “ 5,400 “ “ 
u 
2,600 
a 
A simple calculation gives the average elevation of the land surface at 
640 feet. This is different from the result obtained by others, from I 
known not what data, or assumptions. Bi.it the result can not be far 
from the truth. 
The amount uf water carried off annually by drainage is then 46,000,- 
000 tons. This will develop, in a descent of 640 feet, a total force of 3,- 
370,000 horse power. 
The capacity of all the steam engines, stationary and locomotive, in 
England, as given by the Prussian Bureau of Statistics, is 3,300,000 horse 
powers ; that of the United States, 3,800,000. 
The artificial production of such an amount of force requires the con- 
sumption of more than 4,000,000 tons of coal. 
Some notion may be obtained of the relative cost of water and steam 
power from the fact, mentioned by the State engineer of Maine, vV. 
Wells, that the expenditure for the former, at the water works of the 
city of Philadelphia is less than one fifteenth of the average cost for the 
latter, in four cities, in which coal is $5.50 per ton. 
The actual instrumental measurement of even the principal rivers of 
North Carolina will be a work of time and labor ; but a few such meas- 
urements were made during the past autumn, which are given merely as 
first approximations, being made, of necessity, very rapidly and with im- 
perfect appliances. The figures given are therefore subject to future re- 
vision and correction for errors which, however, can hardly be serious. 
The Roanoke, measured at Haskins’ Ferry, more than 50 miles above 
Weldon, and more than one-third of the distance from the latter point to 
Danville, gives a discharge of 177,000 cubic feet per minute, or 335 horse 
powers for every foot of fall. The entire manufacturing value of this 
stream, so far as its course lies within this State, is about 70,000 horse 
powers. 
The discharge per minute of the Yadkin, measured at Brown’s Ferry, 
near the N. C. Railroad bridge, where the breadth is 650 feet, is 155,155 
cubic feet, which gives 294 horse powers per foot. The river at this point 
is not more than half the size which it attains before leaving the State. If 
therefore 300 horse powers be t iken as an average for the fall of 850 feet 
from Wilkesboro’ to the State line, the aggregate of horse powers devel- 
oped is 255,000. The practical effect of this force may be seen from a 
