amplitude

As a general term, implies extent. In astronomy, it is an arc of the horizon intercepted between the true east or west points thereof, and the centre of the sun, star, or planet, at its rising or setting. In other words, it is the horizontal angular distance of a star from the east or west points. It is eastern or ortive when the heavenly object rises, and western or occiduous when it sets, and is moreover northern or southern according to its quarter of the horizon.

♦ Amplitude, in gunnery, is the range or whole distance of a projectile, or the right horizontal line subtending the curvilineal path in which it moved.

♦ Amplitude, in magnetism, is the difference between the rising and setting of the sun from the east and west points, as indicated by the mariner's or magnetic compass which subtracted from the true amplitude, constitutes the error of the compass, which is the combined effect of variation and local deviation.