pole and from the declination of the stars, by
means of a globe, or tables, or an instrument
whence the variation is perceived by
technical calculation._

{175}

_Right Ascension_ _Declination_
|Oculus Tauri | 62deg 55' | 15deg 53' N |
|Sinister humerus Orionis | 72deg 24' | 4deg 5' N |
|Dexter humerus Orionis | 83deg 30' | 6deg 19' N |
|Praecedens in cingulo Orionis| 77deg 46' | 1deg 16' S |
|Canis major | 97deg 10' | 15deg 55' S |
|Canis minor | 109deg 41' | 5deg 55' N |
|Lucida Hydrae | 137deg 10' | 5deg 3' S |
|Caput Geminorum australe | 110deg 21' | 28deg 30' N |
|Caput boreale | 107deg 4' | 32deg 10' N |
|Cor Leonis | 146deg 8' | 13deg 47' N |
|Cauda Leonis | 171deg 38' | 16deg 30' N |
|Spica Virginis | 195deg 44' | 8deg 34' S |
|Arcturus | 29deg 13' | 21deg 54' N |
|Cor Aquilae | 291deg 56' | 7deg 35' N |

_An instrument for finding the amplitude at rising on the horizon._

Describe the circumference of a circle and let it be divided into quadrants
by two diameters intersecting each other at right angles at its centre. One
of these will represent the aequinoctial circle, the other the axis of the
world. Let each of these quadrants be divided (in the accustomed way) into
90 degrees; on every fifth or tenth of which at each end of each diameter
and on each side let marks (showing the numbers) be inscribed on the two
limbs or margins made for that purpose outside the circumference. Then from
each degree straight lines are drawn parallel to the aequator. You will
then prepare a rule or alhidade equal to the diameter of that circle and
divided throughout into the same parts into which the diameter of the
circle representing the axis of the world is divided. Let there be left a
small appendage attached to the middle of the rule, by which the middle of
the fiducial line itself of the rule may be connected with the centre of
the circle: but to every fifth or tenth part of that rule let numbers be
attached proceeding from the centre toward each side. This circle
represents the plane of the meridian; its centre the actual point of east
or west, _i.e._, the common int