George Ellery Hale (1868-1938) was responsible for convincing the
University of Chicago to help fund the Observatory; he and the president
of the University approached transit tycoon
Charles Tyson Yerkes, who agreed to fund the facility.
Observatory grounds are 80 acres.
Stats on the 40-inch
Dome is 90 feet in diameter and weighs 120 tons.
The dome slit is 11 feet wide and 85 feet long.
The telescope tube is 63 feet long and weighs 6 tons; all the gears
(etc) to move it weigh 20 tons.
It was the biggest telescope in the world in 1897, and it is, in fact,
still the world's biggest refractor.
The floor is 75 feet in diameter and weighs 37.5 tons. It's
held by 4 pairs of cables. It's only fallen once, in May 1897. (For
more information on this, see the 40-inch page.)
The telescope is used nearly every night that weather permits.
The lens has one small crack in it, which was stopped by drilling
a small hole at the end of the crack. It was most likely caused by
water between the lens and the cell that expanded as it froze and
thus exerted pressure on the lens.
The telescope's f ratio is f/19.
The mounting of the telescope was exhibited at the World's Fair
in 1893, called the "Columbian Exposition" and held near the current
campus of the
University of Chicago in Chicago, IL.
The telescope was also involved in the next World's Fair in 1933,
called the "Century of Progress." They set up a
switch on the 40-inch so that when the light from Arcturus (about 40
light-years away) reached the switch,
it would light the lights and "turn on" the 1933 World's Fair. Since Arcturus
is about 40 light years away, the light that left Arcturus 40
years earlier during the Columbian Exposition was now reaching the 1933
Stats on the other telescopes
There are 4 other telescopes permanently mounted at Yerkes:
a 40-inch reflector (called the 41-inch to avoid confusion with the
40-inch refractor), a 24-inch reflector, a 10-inch reflector,
and a Schmidt camera.
The 41-inch (and the Schmidt) is currently used for some of the
scientific research going on at Yerkes.
The 24-inch is currently used in some of the education and
outreach going on at Yerkes.