[Dyac]

There's also another unusual way - the Caisson lock.

Its design is TERRIFYING.

The boat is floated into a tube that get sealed at both ends and then (in the dark..) that tube is winched down into a completely flooded chamber until it (hopefully) lines up with the egress port at the bottom. The tube with the boat in is unsealed and the boat floats out.

https://en.wikipedia.org/wiki/Caisson_lock

[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.

[jodrellblank]

Oh that is terrifying; interesting, it "was first demonstrated at Oakengates on a now lost section of the Shropshire Canal in England in 1792". That little bit of rural UK was hot and happening from 1700 to 1800 and doing a lot of canal and river transport; it claims some part in the Industrial Revolution. Within 20 miles around Oakengates around that time was:

- early good quality cast iron; Abraham Darby in Coalbrookdale in ~1710 smelting iron from low-sulphur coal/coke for the first time, dominating the market in iron pots and pans.

- his foundry casting iron parts for early Newcomen steam engines in 1715 [2].

- the first iron bridge in the world[3] in 1781, now a town called Ironbridge. John Wilkinson invented a method of boring accurate cylinders for Bolton & Watt static steam engines, a friend wrote to him about the proposed iron bridge and he funded it.

- the first iron boat in 1787 in Brosely; the Trial by the same John Wilkinson, "convincing the unbelievers who were 999 in 1000".[7]

- the first iron framed building in the world, ancestor of skyscrapers. Thomas Telford[5] was a surveyor and engineer in the area, took inspiration from the iron bridge and started making other things out of iron, became friends with a flax mill owner whose mill burned down; they decided an iron framed building would be more fire resistant, and they built the first one ever[6] in 1797.

- very early high-pressure steam engine and high-pressure steam locomotive. Richard Trevithick around 1800; Coalbrookdale foundries built a static high pressure engine and a high pressure locomotive[4] within a couple of years of his Puffing-devil road locomotive and Pen-y-Darren rail locomotive were trialled in other parts of the UK.

Then Regression To The Mean happened and the area faded back into history.

[1] https://en.wikipedia.org/wiki/The_Iron_Bridge

[2] https://en.wikipedia.org/wiki/Newcomen_atmospheric_engine#Co...

[3] https://en.wikipedia.org/wiki/The_Iron_Bridge

[4] https://en.wikipedia.org/wiki/Richard_Trevithick#Puffing_Dev...

[5] https://en.wikipedia.org/wiki/Thomas_Telford

[6] https://en.wikipedia.org/wiki/Shrewsbury_Flaxmill_Maltings

[7] https://en.wikipedia.org/wiki/Vulcan_(barge)#Notes