[imurray]

Ooof, I'd never seen that. Thanks! From the wikipedia link:

> The May 1799 test at Oakengates carried a party of investors aboard the vessel, who nearly suffocated before they could be freed.

(!) ...and eventually they built a flight of nineteen locks instead, with a steam-powered pump to return water. The lift locks (and Falkirk Wheel) are a really impressive and elegant solution in comparison.