Tangents to The Sailings

A right line which touches a curve at a single point.

Artificial Tangents. The same as logarithmic tangents.

Logarithmic Tangents. Logarithms of the tangents of arc.

Natural Tangents. Tangents of arc expressed by natural numbers.

The thumb-screw set at a tangent to the arc of a sextant, and which affords a means of gradual motion to the sliding limb after it has been clamped.

An instrument used in coast surveying, being a scale of equal parts painted upon a wooden rod, and used for determining the distance of objects whose lengths are known, from their apparent lengths as viewed between the wires of the telescope.

An optical instrument which makes distant objects more visible by enlarging their images formed in the eye. (See Magnifying Telescope.)

(See Part I.)

As relating to the atmosphere, the degree of heat or cold.

A term applied to stars which have appeared from time to time, shining with great brilliancy, and then entirely vanished.

Relating to the earth.

Meridians connected with secondaries by carrying time in the most careful manner with all the corrections which can be devised.

Secondaries, or Secondary Meridians, are those connected with the prime meridian, directly or indirectly by exchange of telegraphic time signals.

(See Lead and Line.)

(See Line.)

(See Midnight Sun.)

An instrument used in surveying for measuring angles in vertical and horizontal planes.

Navigation depending on or based upon theory; such as calculating the ship's position by observations of the heavenly bodies.

An instrument used for measuring degrees of heat and cold of water and air. It consists of a glass tube containing mercury or colored alcohol, and is secured against a graduated scale.

Deep Sea Thermometer. A thermometer so constructed as to resist the pressure of, water at great depths, and to record the temperature of those waters.

Dry Bulb Thermometer. The ordinary thermometer for recording air temperatures.

Wet Bulb Thermometer. Also known as the Hygrometer. A thermometer having. Its bulb wrapped in thin absorbent muslin with a wick reaching from it into a small cup of water. This instrument measures the humidity of the air.

(See Sailings.)