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The 6" refractor was built in about 1892 by Warner and Swasey in the United States, as were the dome rings. The objective was made by Brashear.
The objective works at f/15 giving a 90" focal length. It is air-spaced and uncoated; the same
is true of the finderscope objective. Neither telescope normally needs any adjustment to its optical
train. Note that the 6" objective has its flat side out rather than the convex side out. The same
is true with the finderscope.
The telescope is on a German-type mounting. It uses bushings instead of ball bearings for the shafts, and the slight friction that is felt on rotation of the telescope is normal.
There are 2 setting circles: both have coarse and fine scales, but the fine scales are difficult to read. Overall mounting alignment is fair, with perhaps a one-half degree error in the declination axis reading. Both circles are rigidly fastened to their respective shafts.
There are tangent arm slow-motions for both axes. At the eyepiece end of the telescope, there are 2 pairs of knobs. The pair that are notched control the right ascension (RA), and the other pair control declination (dec). The inner knob is the locking knob; the outer one the slow motion.
This is a weight driven, centrifugally regulated drive. The driving weights are located inside the pier and are attached to the drive by a pulley riding on a steel cable. The clockdrive will occasionally need oiling.
OPERATION
There is a small crank inside the drive compartment. That crank is inserted into a square driveshaft on the west side of the drive. Turning it cranks up the weight. At the top of the drive mechanism on the east side, there is a lever which brakes the regulating weights. Placing that lever to the north will allow those weights to start spinning and the drive is started.
With the drive weights cranked up, the telescope should run for about 1 1/2 hour.
The drive speed can be altered by adjusting the position of the regulating weights.
In the event that the drive stops suddenly, check the following:
Has the nut on the RA tangent arm (located on the dec housing) moved to the end of the lead screw? If so, turn the RA slow-motion until the tangent arm is over the middle of the screw.
Has the RA lock loosened itself?
Is the brake lever all the way to thenorth?
Are there at least 3 drive weights driving the telescope?
If none of these is the problem, then you should contact the maintenance people immediately and stop using the telescope.
This telescope uses a simple rack-and-pinion focuser. There is also a small locking knob on the back of the focuser. The end of the drawtube is threaded to accept telescope accessories.
OPERATION
The drawtube has some friction until it is racked out about 2". After this, it will slide freely, and the locking knob should be used to hold it. Should the drawtube fail to move easily, make sure that the oil on the drawtube has not congealed.
The dome itself is made primarily of wood that was cut before 1892. The bottom of the dome rests on 3 Civil War (?) cannonballs. There are also 4 retaining wheels on the inside. The shutter is controlled by the 2 pairs of ropes on either side of it, and the dome is controlled by the 3 ropes with handles hanging from it.
OPERATION
To open the shutter, first remove the wooden stick which prevents people from breaking in. This stick is located at the bottom of the shutter, where its lower bearing is. The shutter is opened by gently pulling equally on both ropes on the right; it is closed by the ropes on the left.
If the shutter is hard to move, check to make sure that it has not fallen off its lower bearing. If this is the case, there is a steel pipe in the closet with which you can pry the shutter back on.
The dome itself is normally hard to move, but check to make sure that the 3 cannonballs are located at close to 120 degrees from each other. If you have difficulty with the dome when the slit is pointing to the southeast, try pulling on the rope on the opposite side.
The dome is normally parked with the slit facing east.
Turn the telescope so that the objective is pointing at the bottom of the shutter.
Climb up the ladder, remove the lens cap, remove the stick, check to make sure the shutter is still on its tracks, and then open carefully.
Position the dome for the object being observed, making sure you pull on only the ropes with handles.
Select the appropriate eyepiece. If it is a 1 1/4" eyepiece, then it goes into the end of an adapter. If it is the large eyepiece, then screw out the adapter from the end of the drawtube and screw in the big eyepiece.
When you are through, replace the eyepiece in the telescope with one of the eyepieces that has tape over its end (a dummy eyepiece), and reverse the above proceedings, making sure you
leave the dome pointing to the east (this makes it harder for people to break in), and
leave the telescope pointing towards the pole, with the declination axis pointing down.
Turn the clockdrive off regardless of whether or not it has wound to a stop. This places a bit less stress on the gears.
Lock all the doors and turn out the upstairs lights.
Lock the gate.
Check classroom (both doors), darkroom, all windows, to make sure they are locked.
Note the night's activity in the log book.
Lock outside door.