APPULSE

, in Astronomy, means the actual contact of two luminaries, according to some authors; but others describe it as their near approach to each other, so as to be seen, for instance, within the same telescope.

The appulses of the planets to the fixed stars have | always been very useful to astronomers, as serving to fix and determine the places of the former. The ancients, wanting an easy method of comparing the planets with the ecliptic, which is not visible, had scarce any other way of fixing their situations, but by observing their track among the fixed stars, and marking their appulses to some of those visible points. See Hist. Acad. Scienc. for 1710, pa. 417. And Philos. Trans. No. 369, where Dr. Halley has given a method of determining the places of the planets, by observing their near appulses to the fixed stars. See also Philos. Trans. No. 76, pa. 361, and Mem. Acad. Scienc. for 1708, where Flamsteed and De la Hire have given observations of the moon's appulses to the Pleiades. See also Flamsteed's Historia Cœlestis, where a multitude of observations of appulses, or small distances, of the moon and planets, from the fixed stars, are recorded. And Dr. Halley has published a map or planisphere of the starry zodiac, in which are accurately laid down all the stars to which the moon's appulse has ever been observed in any part of the world. See Philos. Trans. No. 369; or Abridg. vol. vi. pa. 170.