Part of a $6.00 box lot

[Bill Houghton]

They could be read to a thou, but light bends, so they weren't that accurate. Now they use lasers, they don't bend.

Light bends, yes*, but normally only around strong gravitational fields.  Were you doing work near the Sun?
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*Or, according to one interpretation of the General Theory of Relativity, space bends near strong gravitational fields, and the light follows the curvature of space in that area.

[Downwindtracker2]

Heat waves easily bend light, just ask someone who shoots Farky class in the afternoon.