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Upstarts
Survey also enables the batteries all to fire in the same direction, by laying out a
base line common to all batteries, so that each battery can point its howitzers at the same
angle to the base line. [Another method is to lay (point) the battery by compass, at a
given angle from north, but compasses are often erratic.] The survey section made a base
line visible by driving stakes decorated with toilet paper precisely along it. Occasionally a
battery executive would make the unfortunate error of sighting on a roll of toilet paper at
the battery latrine instead of a base line stake, but that was usually caught in time. Or a
truck might run over a stake and knock it down, but drivers soon learned to be careful.
2nd Lt Don Thomson was the survey officer, and one day he invited me to come
and watch while he and his crew ran a practice survey. I went along, hoping to learn
something. And I did. I learned about "breaking" tape on sloping ground, about taping a
distance twice and taking an average - unless, of course, there was a gross difference, say
one inch in a city block, in which case you did it a third time. I also learned how to
calculate distances by triangulation: If you have gotten the length of a line or base by
taping it, you can read the angles from each end of the line to another point and calculate
the distance to it by trigonometry. Then you can use this new distance as a base for
calculating another distance, and so ad infinitum. Lt Thomson had laid out a wonderfully
intricate survey, but by the time the crew finished and did the calculating, the day was
over and the results would have been too late to be very useful. Fortunately, this was a
training exercise, and no one was waiting impatiently for it.
One of the reasons it took so long was that they had two different instruments for
measuring the angles at the ends of a base. One was the aiming circle, like the one I had
used to layout my volleyball court. It was comparatively simple to operate, and all
artillery officers learned how. Unfortunately, it was only accurate to the nearest mil, a
small angle that is 1/6400 of a circle. [The mil is a very convenient measurement for
artillery purposes because if you measure out one mil on something 1,000 yards away, it
will mark out one yard of width. Or at 1,000 inches it will be one inch in width. Or at
1,000 miles, the width will be one mile.]
The other instrument was a transit, which measured angles in degrees, minutes,
and seconds. It was accurate to the nearest 20 seconds, in the order of magnitude of a
tenth of a mil. However, it was a delicate, sensitive instrument and required time, skill,
patience, and sharp eyesight to be fully useful. Some experts said that by the time you got
through converting degrees into mils, you lost all the advantage of the transit's accuracy
anyhow.
That question was never resolved by the 915th survey team, however, because a
couple of months after I watched their exercise, Don Thomson tripped over one leg of the
transit tripod and the whole instrument crashed to the ground, bending a vital brass plate
so that it was inoperable. The transit had to be sent in for repair, and by the end of the
war, three years later, we were still awaiting its return.
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