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HARBOUR ENGINEERING.
of Europe and in America as a definite basis for the establishment of a
systematic code of channel signals.
Fundamental Charaeteristics of Channel Signals.• —-Dealing with
the question, ab initio, it will be evident that the essential features of any
satisfactory system of démarcation are—
(1) Conspicuousness, by which the marks or signals may be seen from a
considerable distance.
(2) Individuality, by which they may be definitely recognised and dis-
tinguished, combined with
(3) Simplicity in regard to their signification, and
(4) Invariableness or unalterability of character.
In the daytime, these conditions are generally fulfilled by beacons and
buoys of definite shape and hue; and at night, by lights of a certain range,
intensity, and colour.
To avoid confusion, it will be desirable, as far as possible, to restrict the use
of the term “ beacon ” to fixed, and of the term “ buoy ” to floating structures.
The surmounting signal of a buoy, however, is commonly also designated a
beacon. Both buoys and beacons may be used as a means of illumination,
but it is solely in regard to their construction and outline that they will be
considered in the first instance.
Beacons.—Beacons, then, are prominent objects or structures on the
Fro. 221. —Beacon.
Fig. 222. —Beacon.
coast-line or on a river bank, capable of acting as a means of alignment,
or as an indication of change of direction. Natural objects, such as lofty
isolated trees; topographical features, such as the edge of a cliff or the
summit of a hill ; and prominent structures of any kind, such as windmills
factory chimneys, and church steeples, may all be used as beacons. When
special erections have to be made, they generally take the form of a wooden