JF Ptak Science Books Post 1525 (Continuing, in a way, an earlier post.)
Sometimes bad ideas aren't really so until they are very, very big--and then put in water. These are some examples of what was probably a propaganda campaign on a disturbing, Twilight Zone-y invitation to imagination of a French invasion of England at about the time of Napoleon. Napoleon I. England had been invaded before, but not by the wily Corsican.
The first apparatus of war was a monumental thing, and was displayed for the world in this engraving, printed ca. 1798-1801. An exact representation of a raft, and its apparatus, as invented by the French for their proposed invasion of England, printed in London by J. Atkin, portrayed the monster: 2500' x 1800', with a enormous stone fortification that seems to have been about 500x500', the thing was powered by four water turbines driven by 550'-tall windmills, it was supposed to be capable of supporting 500 36- and 48-pounder canon, plus 50,000 troops. It looks like it was built for calm water.
This next beast wasn't quite so beastly as the first beast, a beast to the monster. This was the St. Malo seacraft, a thing designed in 1791 that was supposed to be 600x33 feet, supporting the same 500 canon as above, and would transport 15,000 troops. The added feature here--in addition to the windmill-driven engines, was a bomb-proof central structure, which I guess held the troops in safety as the ship was bombarded from the shore.
The unlikely craft below, even though it looks not nearly as large as the preceding two craft, actually carried more troops (60,000) and more canon (600) than the ship. I'm not at all impressed that the design we're looking at here could support a tenth of those numbers. But, on the other hand(s), if it wasn't going to be built and never existed, it really doesn't matter that the scale was all mess up. [Image source: Low Tech Magazine.]
This satirical print shows a French invasion force making its way to England above and below the channel--there are attack balloons as well as a considerable atta-Chunnel.