Editing Canal pound (section)

==History==
Pounds came into being with the development of pound locks to replace the earlier [[flash lock]]s. A key feature of pound locks was that the intervening level between locks remained largely constant, as opposed to the variable levels created by the opening of flash locks.

On some American canals, some pounds acquired nicknames due to the mileage between locks, e.g. the "Eight Mile Level" on the [[Chesapeake and Ohio Canal]] was between Riley's Lock (Lock 24) and Edward's Ferry (Lock 25), a distance of about {{convert|8|mi}}.

===Engineering considerations===
Making a channel that would not leak water is not easily done. Gravel soil or light soil will leak for a few years until it settles and hardens. Puddle or clay would be used to line the channel, but that was not foolproof.<ref name="Oldtowpaths308">{{cite book|last=Harlow|first=Alvin F.|title=Old Towpaths, The Story of The American Canal Era|url=https://archive.org/details/oldtowpathsstory00alvi|year=1926|publisher=D Appleton & Co.|location=New York & London|page=[https://archive.org/details/oldtowpathsstory00alvi/page/308 308]}}</ref> The [[Union Canal (Pennsylvania)|Union Canal]] and the [[Schuylkill canal]] where the canal prism (the shape of the canal as seen in cross section<ref>{{cite web|last1=Thompson|first1=Kristi|title=Glossary|url=https://www.usbr.gov/library/glossary/#C|website=www.usbr.gov|publisher=US Bureau of Reclamation|access-date=15 September 2017|language=en}}</ref>) was blasted through limestone leaked so badly, they had to line the channel with timber.<ref name="Oldtowpaths308"/> The Chesapeake and Ohio canal had frequent cave-ins due to limestone sinkholes near Shepherdstown, near Two Locks above Dam No. 4, around Four Locks, Big pool, and Roundtop Hill near Dam No. 6. requiring expensive repairs.<ref>{{cite web|url=http://www.nps.gov/history/history/online_books/choh/canal_prism_hsr.pdf|title=Historical Structure Report, The Canal Prism, Including Towpath with Canal Berm and River Revetments Historical Data|author=Unrau, Harland D.|publisher=[US Department of the Interior, National Park Service]|access-date=2013-08-02}}, p. 49</ref> After some years, the canal bed would settle and harden, and puddling would no longer be needed.<ref>Old Towpaths, p. 309-310</ref>

====Water supply====
[[File:Patowmack_canal_used_as_feeder_to_C_and_O_Canal.jpg|right|thumb|200px|A feeder canal to feed the Georgetown level of the Chesapeake and Ohio Canal.]]
One main concern to the engineer was the canal's water supply. Pumping would contribute greatly to operating expense, especially at the summit level, hence gravity fed water is preferred. Feeder canals could be {{convert|20|mi|-1}} to {{convert|30|mi|-1}} in length, if needed.<ref name="Oldtowpaths303">Old Towpaths, 303</ref> The canal bed would have to slope so that the water would not flow too fast down the canal and impede the progress of upstream boats.<ref name="Oldtowpaths303"/>

Rivers were often dammed to raise the water's height so that the canal could be fed, for instance, the Chesapeake and Ohio canal had seven dams built to feed water.<ref>Unrau, Historical Resource Survey, p. 241-242</ref>

If a dam was not built, often water had to be pumped. The Chesapeake and Ohio put a steam pump near the South Branch, near mile 174, which had a capacity of about {{cvt|25|cuft/s|m3/s}}, since the water from Dam No. 8 was insufficient.<ref>Hahn, Thomas. Towpath Guilde</ref><ref>{{cite web|url=http://www.nps.gov/history/history/online_books/choh/unrau_hrs.pdf|title=Historical Resource Study: Chesapeake & Ohio Canal|author=Unrau, Harland D.|publisher=[US Department of the Interior, National Park Service]|access-date=2013-05-02}}, p. 470</ref> This problem is particularly acute on summit pounds (see below).

On the [[Pennsylvania Canal (Delaware Division)|Delaware Division]] canal, the Delaware River was made to pump its own water into the canal, using an undershot water wheel which was connected to another wheel which had buckets attached, thereby lifting the river water up to the canal.<ref>Old Towpaths, p. 306</ref>

===Winter===
[[file:Great_Falls_Feeder_Culvert_and_Lock_18_on_Chesapeake_and_Ohio_Canal.jpg|thumb|right|200px|Canal drained for winter. Note: water "stain" on lock masonry indicates normal water level.]]
Where ice would form during winter, the canal prism would usually be closed and drained. During this time, sand bars would be dug out, locks and other structures would be fixed.<ref>Old Towpaths, p. 308-309</ref> Exceptions to this would include wartime necessities, i.e. the Chesapeake and Ohio Canal was left open in the winters of 1861–1862 because of the American Civil War.<ref>Unrau, Historical Resource Survey, p. 724</ref>

===Level walkers and repairs===
American canals often had a man called a "level walker" (Chesapeake and Ohio Canal), "bank watchman" (Erie Canal), towpath walker<ref name="Oldtowpath310">{{cite book|last=Harlow|first=Alvin F.|title=Old Towpaths, The Story of The American Canal Era|url=https://archive.org/details/oldtowpathsstory00alvi|year=1926|publisher=D Appleton & Co.|location=New York & London|page=[https://archive.org/details/oldtowpathsstory00alvi/page/310 310]}}</ref> or inspector whose job was to walk along the pound (level) with a shovel, checking for leaks and repairing minor ones before the leak could cause major damage, and calling the section work crew for major ones. His rounds were about 20 to 24 miles daily.<ref>Kytle, Elizabeth. ''Home on the Canal'', Cabin John, Md. Seven Locks Press, c. 1983. P. 270</ref> [[Muskrats]] would cause leaks by burrowing in the canal, as well as competitors such as stage coach lines or teamsters who would sabotage the canal by digging holes in the bank.<ref>{{cite book|last=Garrity|first=Richard|title=Canal Boatman My Life on Upstate Waterways|year=1977|publisher=Syracuse University Press|location=Syracuse, NY|isbn=0-8156-0139-5|pages=30}}</ref> Other duties included checking the waste weir gates to see if they were letting out the correct amount of water, checking aqueducts for damage, as well as being called in the night to search for missing persons supposedly drowned in the canal.<ref name="Oldtowpath310"/>

If a break or leak was discovered and the level walker could not do repair it himself, he sent a message to the section superintendent or headquarters, and the section crew with a repair scow would come. These boats carried clay straw, takes, rope, wooden boards, and tools (picks & shovels).<ref name="Oldtowpaths311">Old Towpaths, 311</ref> For culverts and flood gates, a row of heavy planks, interlocked with tongue and groove, would be driven across the canal (similar to a cofferdam) above and below the break, and would swell when wet.<ref name="Oldtowpaths311"/> After the water drained out through the break, it would be repaired. If the break was in the bank or berm of the canal, the crew would drive two rows of stakes, about a foot apart, across the breach, then weaving rope between them. Straw was put in it, and that would slow or stop the water flow. A row of planks were then driven to stop the flow, and then the break would be filled with dirt and rocks.<ref name="Oldtowpaths311"/>

Burrowing animals, such as [[muskrats]], would cause leaks by digging holes. [[Indiana]] canals had leaks from burrowing [[crawfish]].<ref name="Old Towpaths, p. 310">Old Towpaths, p. 310</ref> Canal companies would often post bounties for muskrats, e.g. the Middlesex Canal.<ref name="Old Towpaths, p. 310"/>