magnifying glasses.To avoid unknowinglydropping a magnifying glass in the field, youshould attach it to a loop of string. Theinstrumentman puts his head through the loop,retaining the string around the neck, and carryingthe magnifying glass in a pocket. At the end ofeach day’s work, it is a good practice always toreturn the magnifying glass to its proper place inthe instrument case.Adjusting PinsSurveying instruments are built in such a waythat minor adjustments can be performed in thefield without much loss of time while the workis in progress. The adjustments are made byloosening or tightening the capstan screws that areturned by the use of adjusting pins. These pinsare also included in the instrument box. Theycome in various sizes that depend upon the typeof instrument and the hole sizes of its capstanscrews. Use the pin that fits the hole in the capstanhead. If the pin is too small, the head of the screwwill be ruined.Replacements for these pins are generally givenfree of charge by surveying instrument dealers.Like the magnifying glass, adjusting pins shouldbe carried in the pocket and not left in theinstrument box while a survey is in progress. Thiswill save a lot of valuable time when the pins areneeded. Do not use wires, nails, screwdrivers, andthe like, as substitutes for adjusting pins.Tape Repair KitEven though you handle the tape properly andcarefully during field measurements, some tapesstill break under unforeseen circumstances.During chaining operations, when the area is quitefar from the base of operations, the surveyorshould always be sure to have a tape repair kit(fig. 11-55) with him so that he can rejoin anybroken tape in the field, or if the surveyor hasbrought an extra tape, he can take the broken tapeback to the office to be repaired.The tape repair kit usually contains a pair ofsmall snips, the tape sections of proper size andgraduations, a hand punch or bench punch withblock, an assortment of small rivets, a pair oftweezers, a small hammer, and a small file. Beforereusing a repaired tape, always compare it withan Invar or Lovar tape to check it for accuracy.FIELD SUPPLIESField supplies consist principally of a varietyof materials used to mark the locations ofpoints in the field. For example, pencils, fieldnotebooks, and spare handles for sledgehammers45.781Figure 11-55.-Tape repair kit.11-46
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