Dumpy Level

Figure 13 shows a dumpy level and its nomenclature. Notice that the telescope is rigidly fixed to the supporting frame.

Inside the telescope is a ring, or diaphragm, known as the reticle, which supports the cross hairs. The cross hairs are brought into exact focus by manipulating the knurled eyepiece focusing ring near the eyepiece, or the eyepiece itself on some models. If the cross hairs get out of horizontal adjustment, they can be made horizontal again by slackening the reticle adjusting screws and turning the screws in the appropriate direction. Only trained personnel should perform this adjustment.

The object to which you are sighting, regardless of shape, is called a target. Bring the target into clear focus by manipulating the focusing knob shown on top of the telescope. The telescope can be rotated only horizontally, but before it can be rotated, release the azimuth clamp. Train the telescope as nearly on the target as you can, and then tighten the azimuth clamp. Bring the vertical cross hair into exact alignment on the target by rotating the azimuth tangent screw.

The level vial, leveling head, leveling screws, and footplate are all used to adjust the instrument to a perfectly level line of sight once it is mounted on the tripod.