Top image of lunar crater Gassendi › Forums › History › Talk about Irish Astronomer: John Birmingham (1816–1884) › Top image of lunar crater Gassendi 17 September 2019 at 12:27 am #581376 Peter AndersonParticipant Interesting. The drawing is mirror reversed, which since it was too early for the ubiquitous Schmidt – Cassegrains, suggests a diagonal mirror/prism was used with the refractor when the drawing was made.
