The plateswhat is a plate?
A plate is the subject: one mathematical system, captured as a few lines of arithmetic and a set of exposed levers, numbered with a Roman numeral like the survey plates they are. Plate I is the Hopf fibration. There are sixty-eight, and counting.
A plate is not a model on a disk. It is closer to a score than to a sculpture: a compact statement that produces the subject fresh every time it is played, a million points at a time. The levers are part of the subject - they are the system's own parameters, and moving one is how anybody, including the person who wrote it, finds out what the mathematics does.
The plate is not the photograph, either. The same plate under different glass, at a different aperture, developed through a different process, is a different picture - which is exactly the claim the word camera makes. The plates supply the world; the Eidograph decides how it is seen.
Play them
Every plate is playable, live, in the browser: the atlas at prettycloud.io draws them a million points at a time with the levers exposed. Many of them are emergent systems - a few lines of arithmetic and structure nobody put there - which is the reason they are worth photographing at this size, and has its own page here.