The Collaborative International Dictionary of English v.0.48:

Megascope \Meg"a*scope\, n. [Mega- + -scope: cf. F.
   m['e]gascope.]
   A modification of the magic lantern (projector), used esp.
   for throwing a magnified image of an opaque object on a
   screen, solar or artificial light being used.
   [1913 Webster] Megascopic