I was a little surprised, and delighted, to find illustrations dealing with the ideas of UFOs, flying saucers, and machine type things from space, from the 1900s to around the late 1930s. UFO Pop.com is a great resource for images, as well as just goofing off and searching the internet.
I like the phrasing on this one: "early scientification." Not sure what that means, but it sounds, well, "scientifical!"
This one is interesting: fears of giant sized flying saucer machines attacking high rises and sky scrapers like the Empire State building, etc.