SELF-LEVELING LEVEL

You can save time using the self-leveling, or so-called "automatic," level in leveling operations. The self-leveling level (figure 5-3) has completely eliminated the use of the tubular spirit level, which required excessive time because it had to be reset quite often during operation.

The self-leveling level is equipped with a small bull's-eye level and three leveling screws. The leveling screws, which sit on a triangular footplate,

Figure 5-2.-Dumpy level.

are used to center, as much as possible, the bubble of the bull's-eye level. The line of sight automatically becomes horizontal and remains horizontal as long as the bubble remains approximately centered.

HAND LEVEL

The hand level, like all surveying levels, is an instrument that combines a level vial and a sighting device. Figure 5-4 shows the Locke level, a type of hand level. A horizontal line, called an index line, is provided in the sight tube as a reference line. The level vial is mounted atop a slot in the sighting tube in which a reflector is set at a 45 angle. This permits the observer, who is sighting through the tube, to see the object, the position of the level bubble in the vial, and the index line at the same time.

To get the correct sighting through the tube, you should stand straight, using the height of your eye (if known) above the ground to find the target. When your eye height is not known, you can find it by sighting the rod at eye height in front of your body. Since the distances over which you sight a hand level are rather short, no magnification is provided in the tube.

Figure 5-4.-Locke level.

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