Editing Teddington Lock (section)

===Rebuild, 1857===
By 1827 the [[timber]] lock needed considerable repair and in 1829 the weir was destroyed by an accumulation of ice. It is noted that in 1843 the lock keeper prevented a steam vessel from ascending the lock. At that time steam vessels were limited to travel as far (upstream) as Richmond. As originally built, the lock had timber sides up to normal head water level, and turf above that. The crest of the weir was {{convert|3.5|ft|m}} above low water level at Teddington, but following the removal of the piers of old [[London Bridge]] (demolished 1831) in 1832, the drop increased to {{convert|4.5|ft|m}} and increased to {{convert|6|ft|m}} when dredging of the river was carried out.{{sfn |Skempton |1996 |p=166}} At tidally lower water occasional grounding of [[barges]] took place below the bottom sill.

Consideration was given to removing the lock altogether in 1840.<ref>{{cite journal |url=https://books.google.com/books?id=kxJAAAAAYAAJ&pg=PA66 |title=Number II, The Mapledurham Scheme |journal=The Civil Engineers and Architect's Journal |date=February 1840 |volume=13 |page=66}}</ref> However, it was decided to rebuild the lock and in June 1854 proposals included providing capacity for seagoing craft with a side lock for pleasure traffic. In June 1857 the first stone of the new lock was laid at the present position, the central of the three, opened in 1858 together with the narrow [[Thames skiff|skiff]] lock,{{refn|group=n|Nicknamed among lock-keepers and lock users "the coffin"}}. The boat slide, separate, was added in 1869 and in the 1870s the weir collapsed twice causing enormous damage. After the weir had been rebuilt in 1871, sluice bays spanned around {{convert|240|ft|m}}, similar to the tumbling bays.{{refn|group=n|The terms sluice bay and tumbling bay are two types of weir structures; the first, suspended and the second, a rising or fixed barrier.}}{{sfn |Skempton |1996 |p=166}}