_The Method of finding the Longitude by the Eclipses of Jupiter’s
Satellites: The amazing Velocity of Light demonstrated by these
Eclipses._
[Sidenote: First Meridian, and Longitude of places, what.]
207. Geographers arbitrarily choose to call the Meridian of some
remarkable place _the first Meridian_. There they begin their reckoning;
and just so many degrees and minutes as any other place is to the
eastward or westward of that Meridian, so much east or west Longitude
they say it has. A degree is the 360th part of a Circle, be it great or
small; and a minute the 60th part of a degree. The _English_ Geographers
reckon the Longitude from the Meridian of the Royal Observatory at
_Greenwich_, and the _French_ from the Meridian of _Paris_.
[Sidenote: PLATE V.
Fig. II.
Hour Circles.