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carrier by means of grub screw respectively until the ground mark is within the small
circle on the reticle with the alidade at any position. Tighten the screws. This
adjustment should be carried out to the targets at 1.5 and 0.8 meters.
Care of Instruments
J2-2 theodolite is a kind of precision optical instrument. It is vitally important to use
the instrument properly. The following is advisable.
1. Open the container. Lift out instrument, place on tripod and with one hand still
holding the instrument, attach by means of tripod fixing screw. The fixing screw
should not be covertighten. Close the container.
2. When not in use, the instrument should be kept in the container. The store should
be dust proof, have good air circulation and low humidity. There is a bag of silica gel
in the container.
3. If the J2-2 is to be used to the limit of its precision, the plate level should be
protected from direct sun rays.
4. Blow dust off lenses then wipe very carefully with clean cotton wool to remove
moisture or oil.
5. In extreme cold, when instrument is taken indoors or outdoors, don’t lift it out
immediately, but leave it in the container for a while.
