Fig. 43. Levelling Instruments.
Another very simple, but effective, device for finding a level line is by means of a triangle of wood made of half-inch boards from 9 to 12 ft. long [(Fig. 43)]. To make the legs level, set the triangle up on fairly level ground, suspend a plummet from the top and mark on the cross-piece where the line touches it. Then reverse the triangle, end for end, exactly, and mark the new line the plumb-line makes. Now make a new mark exactly half way between the two, and when the plumb-line coincides with this, the two legs are standing on level ground. For short water races this is a very handy method of laying out a level line.
TO MEASURE THE HEIGHT OF A STANDING TREE.
Take a stake about your own height, and walking from the butt of the tree to what you judge to be the height of the timber portion you want, drive your stake into the ground till the top is level with your eyes; now lie straight out on your back, placing your feet against the stake, and sight a point on the tree (see [Fig. 44]). AB equals BC. If BC is, say, 40 ft., that will be the height of your “stick of timber.” Thus, much labour may be saved in felling trees the timber portion of which may afterwards be found to be too short for your purpose.
Fig. 44. Measuring Height of a Standing Tree.