The "fire, control" machines, now used to plot the flight of shells from modern guns in moving ships, against moving targets, deal with practical conditions like this; and the machine pictured could answer a question of this nature, as well as a good many others less specialized. For instance, three or more heavenly bodies (like Earth, Sun, and Moon) are moving in their orbits at different rates of speed and varying distances, attracting each other. What will be the combined result of their forces, in changing the positions of each, in a given period? It is an enormously difficult proposition for the best mathematician in the world. With this machine, its ten "integrators" would be adjusted (by setting dials) to represent the varying factors of the problem, and then started turning. The friction discs and gears of the machine would operate on each other, each of them with an effect proportioned to the energy and speed it represented; and, on the final chart at the "answer table" of the machine (see illustration) a curve would be drawn by a metal pen, representing the formula desired (not necessarily a physical picture of the motion of one of the heavenly bodies, but a mathematical picture of it).
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.