The sidereal messenger of Galileo Galilei : and a part of the preface to Kepler's Dioptrics containing the original account of Galileo's astronomical discoveries (1880)
Galilei, Galileo, 1564-1642, Kepler, Johannes, 1571-1630, Carlos, Edward Stafford · London : Rivingtons · leaf 52
st exact observations, contains 7000Italian miles, CF will be 2000, and CE 1000, and the-2Vth part of the whole, CF, 100 miles. Also let CFbe a diameter of the great circle which divides thebright part of the Moon from the dark part (for,owing to the very great distance of the Sun from theMoon this… … 30 THE SIDEREAL MESSENGER. G c D, which represents the ray that illumines thesummit, in the point D. Then the arc CA or thestraight line c d will be 100 of such units, as c e con-tains 1000. The sum of the squares of DC, CE istherefore 1,010,000, and the square of de is equal tothis; therefore the…
Astronomy
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