Surveying For the Homestead

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Surveying, says Aimee Gelwick, isn't by any means as complex and mysterious as many lay persons believe ... and it can be a very useful and enjoyable skill for the homesteader. In Part 1 of this article (MOTHER NO. 34), the author described how to measure distances and record the findings in field notes, She now turns to the two other basics of the surveyor's art. the determination of comparative elevations and the measurement of angles on the land.

ELEVATIONS

Problems to do with leveling and relative elevations require the following equipment:

[1] A hand level, or surveying level with tripod. The tripod mounted instrument resembles a telescope and can be rotated on its base to indicate where a single elevation will fall anywhere on a 3600 circle around the level's location (see Fig. 8).
[2] A leveling rod with target (see Fig. 9).
[3] A set of chaining pins (see Fig. 1, in MOTHER NO. 34).
[4] A 100 foot steel or metallic woven tape (optional).
[5] Notebook and pencil.

Let's suppose, for example, that you've checked your area's building codes and are about to pour a concrete foundation for that homestead cabin. Here's how you can use surveying techniques to be sure of a level underpinning for your house.

First, place stakes at the corners of the foundation site and run a string around the tops of the markers. You'll then be able to sight the string through the level and adjust the stakes by pounding them into the ground until the cord is horizontal (see Fig. 10). (Or, as is sometimes done, the elevations of the stakes can be compared by setting a target rod on top of each in turn and shooting a reading of the rod as it rests on each stake.)

Set up the level as follows: Screw the instrument to the tripod head, remove the lens cap, and put on the sunshade. Loosen the thumbscrews of the stand and spread the legs, which should be pushed into the ground to make the top of the tripod as nearly horizontal as possible. Then tighten the thumbscrews again. (It's a good idea at this point to take a practice sight on the string or one of the stakes to be sure you I've placed the stand in a favorable working position.)

The next step is to level the sighting instrument on its tripod. (This is a fine operation, and must be rechecked frequently as you work.) Loosen the telescope's locking clamp and swing the instrument to a position directly over one pair of leveling screws. Adjust the pair simultaneously-by turning them in opposite directions-to level the instrument's bubble tube. Then tighten the screws firmly (without jamming them), turn the telescope 90 degrees so that it lines up with the other pair of leveling screws, and center the bubble again. The process is complete when the telltale bead remains in exactly the same position as you rotate the instrument through 360 degrees.