Refroduced fr #2319 the National Archives holdings ad Santiwast Region (5) DLNJrevs 828 —5 3 (1) A level rod with a target attachment as shown on sketch No, 2 is used to measure vertically for the adjustment, The level rod with the target set to a predetermined grade rod is set on the reference beam and the pipe adjusted to it. The operation is repeated at each pipe between adjacent posts, then the beam is moved across to the next posts to continue the adjustments. Horizontal Alignment Due to the height of some of the pipes above ground level this adjustment must be made from controls transfered to the pipe supports as direct measurement from the offset control line is not practical. (1) Establish monumented control points on a line two feet left (or north) of the centerline of the pipe array by offset from the primary horizontal control line, These points should be at approximately the following stations to space them between pipe supports. (a) 0 + 36, (b) 15 + 20, (e) 60 + 00 and (f) 7 + 50. (c) 30 + 06, (ad) Lk + 95, (2) Construct rigid instrument stands and observers platforms at each of these stations to provide a line of sight two feet above the top cross beams of the pipe supports. (3) Set up a theodolite at point cross beams to a target at point (A) and sight over the line of (B), then set a reference mark on line on each cross beam from (A) to a support midway to (B). Set up the instrument at (B) sight on the target at (A), check the last reference mark set from the previous set up and continue marking through to (B). Reverse the instrument and setting on target at marking through to the mid point between (B) and (C). (C) etc. (C) completing setting reference marks through to same method. continue Set up at (F) by the It may be practical to accomplish this operation during day- light hours by taking advantage of favorable atmospheric conditions, if not, it can be accomplished at night. (4) By suspending a heavy plumb bob (32 oz.) from the reference méerk on the top cross beam at each pipe support, establish a reference mark on the lower beam. If any disturbance of the plumb line by wind is experienced, the effect can be dampened by suspending the plumb bob in a container of water, . (S) By horizontal measurement from the reference mark in both directions on the cross beam set a mark at the side of each pipe. offset for one