Bradford reporter. [volume] (Towanda, Pa.) 1844-1884, 1856-02-16
port of New York State Engineer and Sur.

port OF New York State Engineer and Sur
veyor, page l8s. al Laz a.as.ae ee
"The great number of failures in the old
banks of the canal that have occurred the past
season, show conclusively that old banks are
less safe than new ones. Banks annually us
ed and made impervious by sedimentary mat
ter drawn into and deposited as lining on
the face and bottom, will undoubtedly become
more and more safe, but when left to the &c.
tion of rains and frosts for several years. be-
come porous and unsafe, and abound with cav.
tiles where the vegetable matter in the soil has
decayed.
+" Nine years have proved sufficient time to
work great changes in the solidity and COM
pactness Of the old banks 1t is, therefore,
recommended in oil cases where the old banks
are found, to remove the sod to the outside,
and plough and eomminutc thoroughly, to the
depth of twelve to eighteen inches, the mate
rial over the bottom and up the slope of the
prism. This will be found indispensable to
safety. The heavy breaks that have occurred
since the opening of navigation last spring,
were exclusively through the old banks, and
uniformly disclosed loose condition of the
material"
Like results are found in old mill races, and
it is confidently believed that the same would
be exhibited, if water should be excluded for
few years from any of the old and establish
ed lines of canal
The short time that elapsed after my ap-
pointment in the fall of 1854, before the set
ting in of winter, and the pressing duties that
devolved upon me, made it necessary to rely,
in great measure on the information obtain
ed of those who had charge of the line, and of
the foreman who had the season to make OBJ
servations, and who had been superintendng
the repairs, for the condition in whichthe work
was at that time.
They supposed the leakage in the narrows
or rock sections confined to few points, gem
orally well defined, and sufficient to account
for the disappearance of the water
In the " light sections" where the cutting
had exposed strata OF coarse gravel in some
instances of cobble stone and clean river gravel,
it was evident that unless these were removed
and finer material used, that the water would
continue to follow the line of natural drainage
of the country, as it had done for centuries,
and as it obviously did when the experiment
was made by introducing the water, and as
was realized at every rain storm
In making the repairs the past season,
every known expedient has been brought into
requisition, as the peculiar features of the case
demanded. But in general, the tediousness,
expense and unreliability of over hauling with
" pick and shovel" or excavatiug from the bot
tom and side replacing with new material,
made it necessary to adopt some more expedi-
tlouS and economical plan.
Accordingly, force was employed at eyery
point where water could be introduced from
small streams, and wherever the nature of the
material would require and it could be execut-
ed, the ground was ploughed, and the stone
and coarse material exposed in the burrows, or
brought to the surface by the frequent appi-
cation of the harrow, collected by rakes aud
outside of the prism of canal. In
this way the exceptionable portion of the ma
terial only was removed, and that more care
fully selected substituted, and room left by the
of the coarse material for an addition
al quantity of lining, if found necessary. A
heavy cast iron roller was applied both before
aud after the admission of water, for the par-
pose of compression, instead of the usual mode
with commanders. 1t was supposed that the
lining was such, that by oyerhauling the sur
face in this way, leaks would be exposed and
the finer material left would be sufficient to
render that below impervious the rains
showed the porous character of the material
such, that it was afterwards found necessary.
in most cases, to move it to a greater depth,
both in the narrows and light sections, where
gravel occurred, than had been contemplated,
thereby causing unexpected delay and expense.
MECHANICAL Action OF WATER ON EARTH.
The idea has been frequently advanced and
generally by those who had been
engaged in the construction Of the most defcc-
Ire portions of this canal and who in addition
20 their experience on this, claimed knowledge
gained on works for similar purpose, that
al that was necessary to form a good and
perfectly tight canal, was to allow the water !
% pass into it, particularly when in muddy
,r riley condition from freshets that the earth
hen carried forward in solution would be de-
,osited in sufficient quantities to prevent leak
lge" Unfortunately for the theory, it would
,nly apply to the vicinity of the dams on the
eeder levels, as the current is not sufficient to
larry the sediment but a short distance, leav-
ng the remaining places to be stopped by other
means.
Soil being constituted of decomposed rock |
md broken down vegetable tissue, comprising
PARTICLES all shapes and Sizes from stone and |
,ravel to the finest powder, these particles, in
state of nature, resting upon and against |
me another form system of irregular cav-
les or arches. But upon being broken up or
moved, portion of the vegetable matter pas
es off in the form of gases and when in this
'ulverized condition, if water is kept in con
act it percolateS through the mass, displaees
II destroys the adhesion of the particles, and |
.radually brings them into a smaller space,
rhile, the solvent property of the water redu-
es the portion in immediate contact, or the
xternal surface into the state of thin paste, |
which is drawn into the mass by the percola-
ion of the water or capillary attraction, until
he external pores become clogged or imper-
ious, according to the character of the mate
ial used
This Drocess Is gradual and slow in ifs one |