To correct for the stretch of the tape, the latter was stretched with a
force of 15 pounds, and the stretch at intervals of 20 feet measured by a
millimeter scale.

mm.
At 100 feet the stretch was 8.0
80 feet the stretch was 5.0
60 feet the stretch was 5.0
40 feet the stretch was 3.5
20 feet the stretch was 1.5
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300 23.00

Weighted mean = 7.7 mm.
For 10 pounds, stretch = 5.1 mm.
= 0.0167 feet.
Correction for whole distance = +0.33 feet.

The following are the values obtained from five separate measurements of
the distance between the caps of the piers supporting the revolving mirror
and the distant reflector; allowance made in each case for effect of
temperature:

1985.13 feet.
1985.17 feet.
1984.93 feet.
1985.09 feet.
1985.09 feet.
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Mean = 1985.082 feet.