of the Solar Syjlem. 11

27. The inclination of the orbits of theplanets to the plane of the ecliptic, is thecause, why they do not seem to move in theecliptic line, but are sometimes above, andat others below it. In fig. 6. let N V Nbe a circle in the plane of T t the ecliptic,and NAN, the planet’s inclined orbit, Sthe fun, the earth at T, and the planet atA ; if the short line V A be imagined per-pendicular to the plane of the ecliptic, andto pass through the planet at A, the angleVTA, is the latitude of the planet, whichis called the geocentric latitude, to distin-guish it from the heliocentric latitude, asseen from the fun, which is represented bythe angle A S V.

28. When a planet is in the node at N,it appears in the ecliptic line; as it recedesfrom thence its latitude increases and thisis different, according to the situation of theearth ; so that the latitude is greater whenthe earth is at T, and the planet at A, thanwhen the earth is at t, and the planet at V.

29. A planet is said to be in quadraturewhen it is 90 degrees distant from the fun ;the inferior planets cannot be in quadra-ture, as their greatest elongation can never

be