_The Sun’s Altitude being given at any time either before or after Noon,
to find the Hour of the Day, and the Variation of the Compass, in any
known Latitude._
With one hand hold the edge of the Quadrant right against the Sun; and,
with the other hand, turn the Globe westward, if it be in the forenoon,
or eastward if it be in the afternoon, until the Sun’s place at the
inner edge of the Ecliptic cuts the Quadrant in the Sun’s observed
Altitude; and then the Hour Index will point out the time of the day,
and the Quadrant will cut the true Azimuth, or Bearing of the Sun for
that time: the difference between which, and the Bearing shewn by the
Azimuth Compass, shews the variation of the Compass in that place of the
Earth.
[Sidenote: The TRAJECTORIUM LUNARE.