Oh, how they hated this thing. You put your eye (just one) against the brass ocular, and stared and stared and stared, while images jumped before your eyes. It made a clack-clack-clack noise, and gave off a smell of burned dust. While interviewing Henry Giclas (who was on staff at Lowell Observatory) I asked exactly how the comparator was positioned in its room on the first floor of the Main Building; they had arranged it near the window, so you could rest your eyes looking outside. You needed to take a lot of breaks.
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