Designed by
Title
Here is a vintage Blink Comparator used in astronomy #260148041
Description
Blink Comparator: a viewer which holds 2 photographic glass negatives. Plates are put in viewer side- by- side and a lever switches a mirror back-and-forth to view negatives. Stars are fixed in the background on each negative. If a star shows movement between the plates it is a planet. Lowell Observatory: Flagstaff, AZ