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Repair Weir Slots
"Repair weir slots" are
the small vertical indentations in the lock walls before the upstream
gates. There is some debate as to what they were used for. Were they
used during the construction phase of the lock? Were they used when
the lock needed repaired (most likely)? Or were they used for some
other purpose? They are prominent features on seven locks of the
Sandy & Beaver Canal's Eastern Division: Locks 27, 38, 39, 40,
41, 50 and 53. They also appear less prominently on Locks 28 and
31.
They seem to appear on every lock that
has existing face stone where the slots should be. Other locks with
major amounts of existing face stone, 42, 45, 52 and 54, either have
the affected stone missing or buried in the case of Lock 54. It would
be interesting to do a little digging at Lock 54 to see if the slots
exist there too. Richard Heidel's 1955 shot of Lock 42 showed that
the left front area of face stone was still standing at that time.
Unfortunately, the angle of the shot does not show whether there
were was a weir slot or not. The left front area of Lock 42 has long
since collapsed and the face stone seems to have been carted away
from the rubble.
The question remains, did all the locks
of the Sandy & Beaver Canal incorporate repair weir slots? Or
at least the locks that were built in the 1830's with finished stone?
Roy Winkler, a canal buff who lives in
Monaca, PA, e-mailed me this information about weir slots awhile
back:
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Re repair weir slots. They are just that. Slots in
the lock walls down into which a temporary dam (which is what a weir
is)
consisting of a
number of planks as long as the lock was wide could be inserted above
the upper gate to stop the flow of water. The lower gate then opened
to drain the lock and repairs effected. Mostly to repair damage to the
gates caused by rambunctious canal boat captains,or rusted hinges or
maybe ice damage, the gates being the most vulnerable parts of the locks.
Or to plug up leaks in the canal walls or bed. I can't remember exactly
where, maybe on the C&O, or maybe even in Europe, I recall seeing
a sort of crane erected on top of a lock wall at the upper end. Its main
use was to raise and lower panels covering holes near the bottom of the
gates to permit water to enter and raise the level in the chamber for
upstream bound craft. This was easier than trying to open a gate against
the pressure of water holding it closed. The crane was also used to assist
in lowering the weir components into place. This applied only to manually
operated gates, of course. The Corps of Engineer locks on the Ohio use
the same principal, but a much more sophisticated operation.
In logging operations, weir dams were used for sort of the opposite effect.
A temporary, or weir would be erected across a creek to create a pool
into which the logs were rolled. When ready, a King-pin or brace was
knocked loose, allowing the dam to collapse or fall. The backed up water
would course downstream carrying its load of lumber into a larger stream
or river, where the logs would then be corralled and formed into rafts
for a voyage downriver to the next sawmill. I'm not really all that smart.
We used to camp at Clear Creek State Park up on the Clarion River. They
have a lumber museum there with many of the tools used in lumbering along
with descriptions, drawings and even photos of the operations in the
late eighteen hundreds, early 20th century. There were a couple of places
along Clear Creek where remnants of these weir dam abutments could be
seen. |
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