Source : Webster's Revised Unabridged Dictionary (1913)

Photonephograph \Pho`to*neph"o*graph\ (-n[e^]f"[-o]*gr[.a]f), n.
   [Photo- + Gr. ne`fos a cloud + -graph.] (Meteor.)
   A nephoscope registering by photography, commonly consisting
   of a pair of cameras used simultaneously.