464 JOURNAL OF PROCEEDINGS [Mar. 10,

locks and aqueducts, and giving increased height to the lock
gates; a ruling depth of seven feet or more can undoubtedly
be secured tor the levels without disturbing the foundations of
the locks, and without digging out the bottom of the canal,
and without loweriag the crown of the arched culverts.

The greater economy of getting depth of navigation on
your plan is too obvious to require explanation The impor-
tance of leaving the bottom of the canal untouched cannot be
overestimated in our judgment, especially where portions of
the canal has been built through a limestone region All
new canals will waste water at bottom, until in time, a silt
or fine mud settles down, and to a large extent prevents this
leakage. It is therefoie most desirable not to disturb the
bottom of canals.

The Chesapeake and Ohio Canal in many of its levels was
"unfortunately located too low, and has always been a source
of anxiety and often of great cost in consequence of overflow
in time of river floods We have no hesitation in saying
that by increasing the depth of the canal on the plan of your
"new method," this very serious defect in the first structure
of the work will in a great measure be cured, and the Canal
Company will hereafter be saved from those embarrassing
delays and costly evils.

There are other features of your scheme of improvement,
ou which it is not necessary to express our views at the pres-
ent time We need not at this time examine the question of
enlarging the locks and aqueducts, and the canal generally, to
fit it tor the use of boats of 300 tons burden as you suggest.
We see, however, in such points of change as we have above
referred to, abundant merit to command our hearty appro-
val ; and we cheerfully certify as our professional opinion,
that under your "new method" the following valuable re-
sults can be attained:

First. That the prism of the canal can be deepened to
seven feet—or to a greater depth if required.

Secondly. That the canal will be made safer in its whole
distance from the wash and overflow of floods in the river.

Thirdly. That the business of the canal will be but little,
if at all, impeded during the progress of the work.

Lastly. That these beneficial results can be effected at a
greatly reduced expenditure of money.

Respectfully yours,

ISAAC R. TRIMBLE,
CHAS. P. MANNING.