In all of the pictures below, note the scale of things. The lens itself is 40 inches across, and the tube is 63 feet long. This is a big telescope!
This view
of the 40-inch shows tourists seated around the edge of the floor,
listening to the tour guide lecture.
Note the size of the
gears in this picture. Although you can't see them in this picture,
the grease blobs on them are about the size of your fist.
You can barely see
the operator's desk far below, between the pier and the tube.
Note the spiral staircase going up to the telescope.
Another view
of the telescope and pier.
The 75-foot diameter
floor, all 37.5 tons of it, is suspended by 4 pairs of cables, like
the ones our fearless tour guide (Rich Dreiser) is threatening to
grab in this picture. The floor has only fallen once --
at 6:43 am on 29 May 1897, about 1 hour 20 minutes after sunrise, so
(fortunately) there were no astronomers there to be injured.
(The previous evening there had been work going on "adjusting the
telescope" until 9-10 pm.) Half the floor was in the
basement, and the other half was hanging at a terrible angle. It
sheared off half the spiral staircase on the way down, so it was
very fortunate that there was nobody in the dome or on the telescope.
You can read more about this in the
Virtual Museum.
Various views of Professor Kyle
Cudworth near the telescope; the third one has him standing
near where the detectors (photographic plates or eyes) are placed,
and the last one is standing near
the lens. Professor Cudworth
uses the 40-inch refractor nearly every night
that weather permits to study the motions of stars.
The 40-inch is an ideal instrument for this kind of research because
there are lots of pictures taken with
this same instrument over many (more than 100!) years.
There is more description of
his research on the page on science going on at
Yerkes today.
Yes,
people who work here do have a sense of humor.
(yes, that is Spiderman up there!)
This is a close-up of the Moon taken with the 40-inch. This is the
Southern Highlands and (in center) the crater Clavius.
Looking along the 40inch tube at the Moon.
Lots of famous research has been done at Yerkes, much of it with the 40-inch. The 40-inch is used as often as the weather will permit. The current emphasis is stellar proper motions, where the long history of excellent photos from this telescope enables significantly higher precision than anyone else gets anywhere else in the world: combining photos by Ritchey and Barnard before 1910 with those we take now.
Go back to the page on
the telescopes at Yerkes
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