STANDARD - Survey Instrument Antique Center!

58
To adjust the line of collimatioii in Erecting and
Inverting Telescopes.
NOTE: To adjust the line of collimation in a telescope showing objects
erect, follow the simple rule that the diaphragm bearing the wires must be moved
in the direction in which the error is observed (as if to increase the error) ;
in telescopes showing objects inverted the wires must be moved in the direction
lessening the error observed. See diagrams below.
Erecting Telescope.
FIG.I Fio.2
To move the horizontal wire for collimation explained above it must be understood
that the dotted line in the upper half of the field or view, Fig. 1, shows the horizontal
wire where it is actually situated on the reticule, but that through the reversing
action of the erecting eye-piece the cross-wire image is reversed and therefore
the horizontal wire is seen in the lower half as shown in the diagram. Therefore, if
the horizontal wire seen in the lower half of the diagram must be moved upwards,
then contrary to the appearance, screw A must be loosened, and B tightened an
equal amount in order to bodily move the wire reticule towards the center of the
stationary field of view (indicated by the dotted intersection) until one-half of
the error is corrected when the wire will be adjusted and appear in the center of the
field of view, provided the optical axis of the eye-piece has been previously centered.
To move the vertical wire for collimation explained on page 54, remember
that the dotted line at the left, Fig. 2, shows the vertical wire where it is actually
situated on the reticule, but that through the reversal of the cross-wire image by
the use of an erecting eye-piece it is now seen at the right in the field of view in the
diagram; therefore, adjusting screw A must be loosened and B tightened an equal
amount in order that the reticule will bodily move towards B, when the vertical
wire seen at the right will pass towards the center of the stationary field of view
(indicated by the dotted intersection) until one-quarter of the error observed is
removed, when the wire will be in complete adjustment at the optical axis.
Inverting Telescope.
RG.3
FlG.4
To move the horizontal wire for collimation, page 54, the observed error must
be corrected by moving the wire reticule one-half the amount hi the direction it is
lessened, when the telescope is revolved in improvised wyes as in a wye level. Thus,
Fig. 3, if the wire must be moved down, A must be loosened and B tightened an equal
amount.
To move the vertical wire for collimation explained above, the observed error
must be corrected by moving the wire recticule one-quarter of the amount in the
direction it is lessened. Therefore, if the wire must come to the right, A, Fig. 4, must
be loosened, and B tightened an equal amount until the object is attained.
B