If human thought is a growth, like all other growths, its logic is without foundation of its own, and is only the adjusting constructiveness of all other growing things. A tree can not find out, as it were, how to blossom, until comes blossom-time. A social growth cannot find out the use of steam engines, until comes steam-engine-time.
Charles Fort Lo!
Last time, we looked at the early fictional tanks but the actual evolution and appearance of the tank itself is interesting. I was largely pondering how far you could plausibly push technology and it still seem feasible - bringing early 20th Century technology into the 19th Century without the need to get too fantastical (granted it is for an Invasion Literature/zombie mash-up but already required the suspension of disbelief in a couple of areas, so I wanted to keep the technology itself realistic, just move progress forward a few decades in response to the threat). I have given a lot of thought to the 1896/1897 airship flap in the past, so largely had that angle boxed of, but what about tanks?
I have had my eye on steam-driven tanks for a while, with a thought to deploying them at some point, as I didn’t want to take the easy route and simply time-shift a standard tank.
The American steam tank from 1918 is pretty much the classic British lozenge-shaped tanks with a kerosene engine, which just seemed to easy (and it wouldn’t make sense story-wise because we are really just adapting a successful design to run on steam):
However, the Steam Wheel Tank (from some time around 1916 and 1917) is much more interesting, it stems from the period when the design of tanks was still very much in flux and one failed branch were the big wheel designs (leading to some of a large number of strange tanks):
The same kind of thinking led to the Treffas-Wagen:
What caught my interest was the fact that they are, essentially, armoured traction engines or steamrollers, which seems like a route you might take if you had to improvise a tank-like vehicle. So the design I’m leaning towards (although the artist has yet to be consulted and he might bring more ideas into the mix) is a traction engine/steam roller with armour around the base and perhaps a lighter Frank Reade style shooting platform on top (as the threat is not going to be armed and living men, you just need something to keep the living dead from getting jammed in the workings and provide a more open area for the troops, with some wire mesh to keep back any of the rotters that can climb).
However, I did wonder how much we could push it and if there was anything in the pre-history of tanks that would help. There are early pre-cursors to the tank like Da Vinci’s famous sketch (used in Defoe):
As well as this fighting unicorn, apparently:
However, it was this nugget that clinched it for me:
The caterpillar track, upon which the tank travelled, was designed in its crudest form in 1770 by Richard Edgeworth. The Crimean War saw a relatively small number of steam powered tractors developed using the caterpillar track to manoeuvre around the battlefield’s muddy terrain.
Thus even in the 1850s the development of the tank seemed tantalisingly close - except that its development dimmed until the turn of the century.