vary
as the 1.52 to the 1.87 powers of these grades. How this will agree
with the results obtained from properly conducted experiments on
increasing from 4 or 4-1/2 to 8 or 9 per cent, grades remains to be
ascertained. Mr. Hamilton Smith, Jr., considers that under these
circumstances the transporting power (capacity) of the sluice will
increase about with the square of the inclination.
Mr. P. M. Randall says that the transporting power (capacity) of water is as the 3.75 power of the velocity.
From
official data of the Blue Tent Company of the amounts of light material
washed on a 10-1/2 per cent, grade, it would appear that the
transporting capacity for such material varies as the 1.20 power of the
grade.
The
time, means, and facilities for the careful and thorough investigation
and determination of the duty of the miner's inch have not as yet been
afforded to the engineers who have been appointed for this purpose. In
most cases the amounts of material estimated to have been removed may
be considered as mere approximations, as is evidenced by the wide
differences in the many estimates which are given in the various
publications.
In the suit of the State of California vs. the
Gold Run Ditch and Mining Company the estimates of the amounts of
material washed and remaining, made by the various engineers who had
investigated the subject, showed differences as great as 33 per cent,
where the question of size of excavations and cubic contents was alone
at issue. The difference arose largely from attempts to reconstruct
from insufficient data the former topography of the land mined, no
accurate information upon the point being obtainable.
The
only known attempts at any extended and detailed investigation of the
duty of the miner's inch have been made by the North Bloomfield and the
La Grange Hydraulic Mining Companies. The results of the work
performed at these mines are given in the annexed tabulated statement:
