A manned station providing a light usually of high intensity and reliability. It may also provide sound signal and radiobeacon services.

Related Terms


A measure of the ability of an insulating material to withstand electric stress (voltage) without failure. Fluids with high dielectric strength (usually expressed in volts or kilovolts) are good electrical insulators. (ASTM Designation D 877.)


Coked material remaining after an oil has been exposed to high temperatures under controlled conditions.


A device to transfer heat from a low temperature to a high temperature medium.


Works on the basis that atoms of metallic and other particular elements emit light at characteristic wavelengths when they are excited in a flame, arc, or spark. Excited light is directed through an entrance slit in the spectrometer. This light penetrates the slit, falls on a grate, and is dispersed and reflected. The spectrometer is calibrated by a series of standard samples containing known amounts of the elements of interest. By exciting these standard samples, an analytical curve can be established which gives the relationship between the light intensity and its concentration in the fluid.


Adhesion of the molecules of gases, liquids, or dissolved substances to a solid surface, resulting in relatively high concentration of the molecules at the place of contact; e.g. the plating out of an anti-wear additive on metal surfaces.


A lock of very large size and usually of irregular shape, the gates of which are kept open for several hours after high tide so that vessels may enter as long as there is sufficient depth over the sill. Vessels remain in the half-tide basin until the ensuing flood tide before they may pass through the gate to the inner harbor. If entry to the inner harbor is required before this time, water must be admitted to the half-tide basin from some external source.


An occulting light in which the occultations are combined in groups, each group including the same number of occultations, and in which the groups are repeated at regular intervals. The intervals of light separating the occultations within each group are of equal duration and this duration is clearly shorter than the duration of the interval of light between two successive groups.


The difference between the heights of the two high waters during a tidal day


The maximum height reached by a rising tide. The height may be due solely to the periodic tidal forces or it may have super- imposed upon it the effects of prevailing meteorological condi- tions. Use of the synonymous term HIGH TIDE is discouraged.


A light sounding lead (7 to 14 pounds), usually having a line of not more than 25 fathoms

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