(a) In telegraphy the return stroke of the lever in a telegraph sounder, striking the end of the regulating screw with a sound distinct from that which it produces on the forward stroke as it approaches the magnet poles. It is an important factor in receiving by ear or sound reading. (b) See Back Shock [...]

A lightning stroke received after the main discharge of the lightning, and caused by a charge induced in neighboring surfaces by the main discharge. The discharge affects the evenness of distribution of surrounding surfaces so that a species of secondary discharge is required to make even the distribution, or to supply charge where needed to [...]

A demagnetizing force produced in a dynamo armature when a lead is given the brushes. The windings by such setting of the brushes are virtually divided into two sets, one a direct magnetizing set, the other a cross magnetizing set. The latter have a component due to the obliqueness of the neutral line, which component [...]

Abbreviation for British Association. It is prefixed to standards fixed by the committee of the British Association for the Advancement of Science. Thus the B. A. ohm means the British Association ohm, a measure of resistance which is equal to the resistance of a column of mercury 104.9 centimeters long and one square millimeter area [...]

(a) Abbreviation for Baumé, a hydrometer scale. (See Baumé.) Thus 10º B. means “ten degrees Baumé.” (b) Symbol for the coefficient of induced magnetization, or the number of lines per square centimeter induced in a magnetic circuit or in any specified part of it.

A great circle, whose plane passes through the zenith or point of the heavens directly overhead; any great circle in whose plane the vertical at the point of observation is included. Each celestial body has or determines an azimuth circle.

The angle between the plane of the meridian and the plane of an azimuth circle, q. v.

In a system of rectilinear right angle co-ordinates, the vertical axis. (See Co-ordinates.) Synonym–Axis of Y.

In a system of rectilinear, or right angle co-ordinates, the horizontal axis. (See Co-ordinates.) Synonym–Axis of X.

The electric axis of a pyroelectric crystal, such as a tourmaline crystal; the line connecting the points of greatest pyroelectric excitability.