from The Century Dictionary.
- noun A fluorescent screen, with a hood, for the observation of bodies under the action of X-rays; a *fluoroscope (which see, with cut).
Sorry, no etymologies found.
Salvioni to this sort of "spy-glass" -- if one may apply this term to an instrument which has no glass -- is that of "cryptoscope" (seeing that which is hidden).
Salvioni of Perugia has invented a "cryptoscope," which enables us to see the hidden object without the aid of photography by allowing the rays to fall on a plate coated with one of these phosphorescent substances.