...rotation of the earth and are also at the same instant different for different places on thejgparth. But as it is necessary for certain purposes to give...the angle at the pole measured by it, is called the hour-angle of the star. It is used as the second co-ordinate and is reckoned in the direction of the...

...and the pole the polar-distance of the star. The great circle itself is called the declination-circle of the star. The declination is positive, when the...it is south of the equator. The declination and the polar-distance are the complements of each other. They correspond to the altitude and the zenith-distance...

...latitude of the place. Then, from the figure, 0 = 90° - A + *. (45) in which S is positive when the sun is north of the equator and negative when it is south of the equator. On the ocean the altitude is taken by bringing down the image of the sun until its lower limb touches...

...place of observaB tion. The angle QAS is the declination of the sun, which is positive when the sun is north of the equator and negative when it is south of the equator. The lower part of the figure is a plan, A being the place of the instrument, NM the true meridian, W and...

...latitude of the place. Then, from the figure, 0 = 90° - h + S, (45) in which S is positive when the sun is north of the equator and negative when it is south of the equator. On the ocean the altitude is taken by bringing down the image of the sun until its lower limb touches...