INTRODUCTION. 
39 
that the water power of the State is enormous and distributed over its 
whole territory except the immediate seaboard. 
And only the larger class of streams has been included in the fore- 
going calculation, while hundreds of creeks, many of them large enough 
to be classed as rivers in other countries, — larger than the Tiber or the 
Arno — and of sufficient power for an indefinite number of mills and 
factories, have not even been named. In the piedmont and mountain 
regions especially, exist a multitude of streams, affluents of the great 
rivers, which in their descent of hundreds of feet from the upper slopes 
and table lands develop an aggregate amount of force, probably not much 
less than that of the main streams. 
But it is not impossible to reach some definite conception of the amount 
of this mechanical power. We may arrive at such a result in several 
ways. The data already obtained for the aggregates of the river lengths 
and falls will serve as the basis of a first approximation to an estimate, 
if we add another which can only be obtained by an actual measurement 
of the power developed by such an average river as the Haw or the 
House in a given amount of fall. Such a measurement of Haw River 
lately made at its confluence with Deep River, gives a force which may 
be expressed simply as 200 horse powers per foot of fall, after deducting- 
ten per cent, for a slight rise in the river. If the half of this be taken 
as the average for the whole length of the stream, the additional datum 
required is 100 horse powers per foot of fall, for a river 3300 miles long 
and falling 10 feet to the mile. This gives a total mechanical effect of 
3,300,000 horse powers. 
A second approximation may be reached by starting from an entirely 
different point of departure. Given the average annual rainfall for the 
State, the proportion of it which escapes by evaporation and the average 
elevation of the surface above sea level, the dynamical effect of the de- 
scent of the residuum through the known vertical height is readily calcu- 
lable. The average annual rainfall, as stated elsewhere, is certainly not 
under 45 inches. If the loss by evaporation is assumed to be 70 per 
cent., which is rather over than under the fact, the residuum to be ac- 
counted for by drainage is 13^ inches. 
The average elevation of the surface may be obtained approximately 
from 1 lie following data, viz : 
50.700 square miles. 
3,300 “ “ 
47,400 “ “ 
15.000 . “ “ Elevation, 50’ feet. 
Area of the State, 
“ “ sounds, 
“ “ land surface, 
■“ “ coast region, 
