Dennis, I'm not sure what you're refering to as the reticle screws? If they are the four capstan style screws around the barrel of the scope - again, I wouldn't mess with them. If your crosshairs are broken (something I've only seen once in 100's of instruments) you will probably need to send it off for repair. Make sure they aren't simply out of focus. They can be completely invisible if the crosshair focus control is turned to the extremes. That focus control is around the eyepiece, or the reticle as some folks call it. Your eyebrow will touch the crosshair focus control as you look thru the eyepiece. I've never used that particular model of instrument, but they are all pretty similar.
Level math is pretty straightforward. Everything is worked off of the heighth of instrument, or HI. Suppose you took a rod reading on the flowline of the upstream end of a pipe culvert and read 5.0 on the rod. A shot of 5.5 on the flowline at the downstream end would indicate 0.5 feet of fall in that run of pipe. If you were to assign an elevation of 100.0 to that same upstream flowline, then the HI would be 105.0. Subtract the 5.5 reading at the downstream end and you would have 99.5 for an assumed elevation. You could shoot anything within range and subtract the reading from your HI of 105.0 to establish a relationship.
If you're working in hilly terrain, it gets mildly complicated. Your rod will be too short, or you'll be looking into the ground below the rod. Then you've got to learn how to make a "turn". It basicly involves establishing an elevation on a solid object, such as the downstream flowline of the pipe I mentioned earlier. You know the flowline of the DS end is 99.5. Pick up the instrument and re-set it for convenient readings, take a new shot on the DS flowline (say 12.5) and add 12.5 to the known elevation of 99.5 - your new HI is 112.0. Now you subtract every shot at your new set-up from the HI of 112.0.
You can carry an elevation for miles using this method, but if it's critical work, you must make a complete "loop" back to the original or another known elevation to prove your accuracy. Otherwise you are "open ended", and may be working off of a busted shot or math error. You should be able to complete your loop within a couple hundredths of a foot, depending on what level of accuracy you're needing, of course. A tip: On "turns", add your backsight readings and subtract your foresight readings. And remember to keep your shots balanced. Your rodman should take the same number of steps walking to you as he takes walking on past you.
More boring info that you probably already knew :-)
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