This machine was used to measure the small dots that made up the star images on glass plate negatives. It was made in 1915. Most of the plates used on this measurer were exposed at the Observatory's astrographic station near Pennant Hills. However, it was quicker and easier to take photographs than to measure them. By the time this machine was purchased there were 20 years worth of plates waiting to be measured.
This information is from the exhibition "By the light of the southern stars" at Sydney Observatory, part of the Powerhouse Museum.
© Powerhouse Museum