Bearings by Compass, Sun, &c. 285
tion ; but compass observations on hill-tops, if unchecked by a sextant observation of the sun's bearings, are never so reliable as those taken on a plain.
Bearings by Sun and Stars.-It requires very great practice to steer well by stars, for, on an average, they change their bearings even faster than they change their altitudes. In tropical countries, the zodiacal stars-as Orion and Antaresgive excellent east and west points. The Great Bear is useful when the North Pole cannot be seen, for you may calculate
