Chaining
While I know that quite a number of surveyors performed the right procedures I know that in the two companies I worked for before I moved to NGS no one ever had the thermometer attached to the tape and rarely even had one in the field.
Chaining
> While I know that quite a number of surveyors performed the right procedures I know that in the two companies I worked for before I moved to NGS no one ever had the thermometer attached to the tape and rarely even had one in the field.
I carried a thermometer, tension handle, and tape clamps in my vest. The thermometer measured air temperature and by just not laying the tape flat on a super-heated surface, errors of tape temperature were minimized. Naturally, a dark-finished tape in bright sun will tend to be hotter than ambient air. It's been long enough ago that I can't recall how I determined how much hotter the tape was at equilibrium (i.e. when it was losing heat to the ambient air at the same rate it was absorbing it from sunlight).
(Edit: I just remembered. The field thermometer had an aluminum housing that I darkened so that by leaving it suspended in sunlight the thermometer would gain heat from solar radiation. It also had a lanyard by which one could swing the thermometer through the air to get a good measurement of ambient air temp.)
Slope Chaining?
Chained many miles with a 300' tape using a plumb bob on each end holding waist high, a clino for verticle angles shooting close to the same height as my eye level on the other chainman and using the "Red Book" Traverse Tables to get the horizontal distance. Didn't have to figure anything, it was all there in the tables.
I got the opportunity about 20 years (1986) later to check a couple of the lines with an HP 3810A when I was doing a survey for my son-in-law, one was a ¼ mile that was .05' and the other was a ½ mile that checked 0.35'. These were on some sectional sudivision lines I had done for fencing a reservoir boundary in 1965 when I worked for the USBR.
Slope Chaining?
I understand. I am chronically amazed. We often check within 0.10' - 0.20' per 1/4 mile.
We did work hard.
I wish we had spent a proportionate amount of time, on the legal locations we were setting.
N
