The record-union., 1895-04-26
PERISHABLE MATERIAL FOR RE-
STREAMING DAMS.

Some of our contemporaries have
raised the question as to the infallibility
of engineering testimony. We are per-
fectly willing to discuss this question
with our contemporaries, with engineers
and with all comers.
When the bill known as the drainage
bill was passed there was much Haunting
of engineering testimony. The late James
B. Eads, assisted by that distinguished
engineer, Mr. Corthen, inspected the
Parks dam in the Yuba River, and pro-
nOunced it first-class. Mr.. Eads was
personally interviewed by the RECORD
UNION, and gave his unqualified opinion
that the dam being constructed by Mr..
Parks was in all respects perfectly safe
and reliable, and adapted for the purpose
for which it was designed. Mr.. Eads had
all the data relating to the subject at his
command, the maximum floods of the
river, the quantity of debris, so far as it
had been ascertained; and from this data
gave an opinion favorable to the perma-
nency of the structure being erected. He
made some suggestions which were care
fully observed, SO that the Parks restrain
ing dam, now historical as stupendous
failure, was the work of the most emil
nent civil engineer Of this century.
The entire policy of restraining hy-
draulic detritus was based on the testi-
mony of eminent engineers and it failed.
But we. present now for the consideration
of our esteemed contemporaries a fact SO
completely within the knowledge of
every body that engineering science need
not be appealed to. 1t is as follows:
In the list of mines permitted to pursue
hydraulic mining published by the De-
bris Commission, about sixty per cent.
of them proposed to restrain the earth
sluiced into the channels OF the stream
with brush and log dams We ask peo-
pie of common sense-not of engineering
attainment-if wood in the form of brush
and logs will not decay? Is there any
man so great fool as to answer in the
A0BdLAN6s lS II uOL huOMu luAL "OOu
will decay, and that it decays more easily
in the form of brush and logs than in
hewn or sawed timber? The list of
mines permitted to pursue hydraulic
mining behind woodwork of this kind is
as already stated. and therefore the ques-
ton arises if the detritus is to be re-
foT l,r-,r
be retained after the wood and the brush
rot. Since no man is foolhardy enough
70 deny the perishable nature of wood
and brush, does it not follow as a logical
conclusion, and one which may not be
either doubted or gainsaid, that wood
and brush dams are merely temporary
the channel of stream wherein by nat
ural erosion the channel has been worn
to its present grade, the detritus will be
moved and the bed of the stream cleaned,
unless restrained by a physical obstruc-
ton which retains it. Therefore when
the grade in the bed Of the stream is raised
by wood or brush dams, it will remain at
that grade only so long as the wood and
brush do not decay.
Here, then, is conclusive testimony on
the folly of the proceeding. 1t is not
debatable question, since the perishable
nature of wood and brush is not doubt
ful. 1t is not a matter to be brushed
aside as of no consequence or moment
1t is an irrefragable truth that wood and
brush will decay, and that the engineer
who is depending upon them for the per-
manent detention of injurious material
bound to come down the stream is a SIM
pie fool, no matter what his engineering
attainment may be. This is not vituper-
ative statement. 1t is the plainest truth,
plainly expressed. 1t has the cogency of
common sense and the irresistible power
of inherent automatic truth.