Repository: UIHistories Project: Board of Trustees Minutes - 1880 [PAGE 62]

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Jacob's staff; or it may be used on an ordinary carpenter's trestle, with a wedge or screw under one end; or a regular tripod can easily be made, as follows: From a two-inch board, saw a triangle, 10 or 12 inches on each side. Procure three pieces for legs, an inch thick, two inches wide at one end and tapering nearly to a point at the other, and four and a half or five feet long. Bore holes through the wide ends of the legs and bolt the corners of the triangular block with half-inch bolts and thumb nuts. In the middle of the top of the triangular block, fasten a piece one inch thick, two inches wideband as long as the level, by a screw through the middle, so that it can turn in any direction. On the sides of the last mentioned piece fasten little strips, to keep the level from falling off. A short bolt or long screw through one end of this strip, for raising or lowering the level, completes the instrument. The cost in time or money is insignificant, nor do these improvements injure the carpenter's level for its ordinary purposes. A rod can easily be marked off into feet, inches, and fractions, to measure differences of level with. A piece of white paper, held by hand, will do- for the target. To adjust the sights more accurately than by the method previously described, either of two methods may be used: First Method.—This method is applicable when a sheet of still water can be obtained. Set the instrument quite close to the edge of the water, level it approximately by moving the legs and thus level it accurately by the screw under one end of the level. Near the instrument drive a stake until the head is even with the surface of the water; drive another further away, say 100 feet. Hold the rod on the first stake, sight, and note the reading. Do the same for the other stake. If the readings are the same, the sights are correct. If they are not, move one or the other sight up or down until the two readings are the same. Second Method.—If a sheet of still water is not at hand, drive two stakes in the ground and place the instrument between them. Level the instrument right at the rod and note the reading for each stake. The difference of these readings is the true difference in level of the stake, whether the sights are correct or not. Set the instrument over one of the stakes and level it. With the rod, measure from the top of the stake to the line of the sights, and make note of the distance. Hold the rod upon the other stake, sight with the instrument and note the reading. If the difference of the last two readings is the same as that of the first two, the sights are correct; if it is not, move the sight until"the last difference is; the same as in the first case. Cheap leveling instruments can be bought in the cities; but it is claimed that the farmer can make the one described above with little or no expense, and have an instrument less liable to get out of adjustment, and as accurate as the cheap instruments sold as "farm drainage levels." One made by the writer for a farmer has been in constant use on the farm and has proven itself a very valuable instrument. In using the instrument, first see that it is in adjustment; secondly, if possible, set it half way between the points whose difference of level is to be determined; and thirdly* avoid sight longer than 250 or 300 feet.