A high-school astronomy: in which the descriptive, physical, and practical are combined .. (1853)
Mattison, Hiram, 1811-1868 · New York, F. J. Huntingdon [etc.] · leaf 127
the earths penumbra,till at length she comes in contact with the umbra, andthe real eclipse begins. 260. In order to measure and record the extent ofeclipses, the apparent diameters of the sun and moonare divided into twelve equal parts, called digits / andin predicting eclipses, astronomers… … TWELVE DIGITS. urn ^<*J&>
Astronomy
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