Sky and Telescope - July 2017 - 28
A TECHNOLOGY PAST ITS LIMIT
by Jeff Hecht
The Lesson of the
PUBLIC DISPLAY The Paris Exposition Universelle of 1900 was meant to be the grandest world's fair of all time, and the Great Paris Telescope was
one of its most impressive exhibits. A siderostat mirror followed the turning sky and directed light into a 49¼-inch f/48 refractor, fixed horizontally.
Two objective lenses were made, one for visual and one for photographic use. During daytime the Sun could be projected onto an enormous indoor
screen in a darkened auditorium, as in the drawing at top.
J U L Y 2 0 1 7 * SK Y & TELESCOPE