Considering what he worked with
Went to the Lowell Observatory in Flagstaff, Arizona back in mid-80's and man, was that primtive! No ccd's or posh hotels, just a basic dome and telescope and boy, it musta been cold taking those long exposures on glass plates! BTW, if you get the chance, visit this gem of observation, it's like a time capsule on early explorations of the heavens with a telescope.