Editing Lock (water navigation) (section)

===Stop locks===
When variable conditions meant that a higher water level in the new canal could not be guaranteed, then the older company would also build a stop lock (under its own control, with gates pointing towards its own canal) which could be closed when the new canal was low. This resulted in a sequential pair of locks, with gates pointing in opposite directions: one example was at Hall Green near [[Kidsgrove]], where the southern terminus of the [[Macclesfield Canal]] joined the [[Hall Green Branch]] of the earlier [[Trent and Mersey Canal]]. The four gate stop lock near Kings Norton Junction, between the [[Stratford-upon-Avon Canal]] and the [[Worcester and Birmingham Canal]] was replaced in 1914 by a pair of [[guillotine lock]] gates which stopped the water flow regardless of which canal was higher. These gates have been permanently open since nationalisation.<ref>''Birmingham's Canals'', Ray Shill, 1999, 2002, {{ISBN|0-7509-2077-7}}</ref>