This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 Excerpt: ...Unclamp the vernier plate and turn it around until the intersection again strikes B. Clamp the vernier plate and revolve the telescope again. If the intersection now strikes C the line of sight is adjusted. If it strikes some other point, D, move the intersection by the side cross wire screws over one-fourth the ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 Excerpt: ...Unclamp the vernier plate and turn it around until the intersection again strikes B. Clamp the vernier plate and revolve the telescope again. If the intersection now strikes C the line of sight is adjusted. If it strikes some other point, D, move the intersection by the side cross wire screws over one-fourth the distance DC. The eyepiece inverts the cross wires; so that if the right screw is tightened the intersection will apparently move to the left, and vice versa, Repeat the entire operation and continue until the intersection will strike the same point both times when the telescope is revolved. The movement of the cross-wire ring may have disturbed the adjustment of the wire, if so, readjust them. Then examine the line of sight again, and readjust it if necessary. Repeat these operations until both adjustments are found correct. To adjust the telescope level: Level the horizontal limb carefully and make the telescope as nearly level as possible by the eye or with the telescope level. Drive a stake about 200 feet from the instrument; have a graduated rod held vertically on top of the stake; direct the telescope on the rod and note carefully the point cut by the horizontal wire. Place another stake in the opposite direction at exactly the same distance from the transit as the other; have the rod set vertically on the top of this stake; turn the horizontal limb, being careful not to disturb the telescope; direct again on the rod by the limb clamp and tangent screws, and have the second stake driven in the ground until the horizontal wire cuts the rod at the same height as before. The top of the two stakes will then be in the same horizontal plane, whether the telescope is level or not. Carry the transit to a point on the same side of both stakes, in line w...
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