“Yet on the earth clean men we walked,
Glutton and Thief and Lover;
White flesh and fair it hid our stains
That no man might discover.”
“Naked the soul goes up to God,
Brother, my brother.”
—Theodosia Garrison, Zion’s Herald.
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STANDARDS
For measuring a base line (in calculating a parallax) metal bars or rods are used. These are carefully compared in the laboratory with the standards and their lengths at a definite temperature determined. Unfortunately, when these rods are taken into the field for actual use they are exposed to constantly varying temperatures, and they expand and contract in a very troublesome way. Various devices have been used to eliminate the errors thus introduced, the simplest and best being the Woodward “ice-bar apparatus” used by the Coast and Geodetic Survey. In this the metal measuring-bar is supported in a trough and completely packed in ice, and thus maintained at the uniform temperature of 32 degrees Fahr. With such an apparatus a base line can be measured with an error of only a fortieth of an inch in a mile, or one part in two and a half million.—Charles Lane Poor, “The Solar System.”