CLU 
water is elevated again only by being con- 
verted into invisible vapour. See Me- 
teorology. 
CLUE, in marine language, is the lower 
corners of square sails ; but the aftmost 
only of stay-sails, &c. ; the other lower cor- 
ner being called the tack. 
Clues of a hammock, the combination 
of small lines by which it is suspended. 
CLUPEA, the herring, in natural histo- 
ry, a genus of fishes of the order Abdomi- 
nales. Generic character : head compress- 
ed ; mouth compressed and internally 
rough j jaws unequal; tongue short and 
rough; with inverted teeth; side-plates of 
the upper mandible serrated ; gill-mem- 
brane eight-rayed ; gills setaceous inter- 
nally ; abdomen sharp and generally ser- 
rated ; body compressed, elongated, and 
covered with moderate scales ; ventral 
fins often nine-rayed;. tail forked. There 
are fifteen species, according to Gmelin, 
and according to Shaw, nineteen ; of which 
the most deserving of notice are C. hai’en- 
gus, or the common herring. 
This fish does not appear to have been 
known by the Greeks and Romans, or at 
least to have attracted from them any par- 
ticular attention. In modem times it con- 
stitutes an important article of commerce, 
and the herring fishery has lor ages been 
considered as an important field for na- 
tional industry, and a source of national 
wealth. Even in the twelfth century the 
Dutch were much occupied in taking her- 
rings, and preserved a sort of monopoly on 
this subject for several ages. The art of 
pickling them was discovered in Flanders. 
The Dutch are uncommonly partial to the 
pickled herring, and on the arrival of the 
fii-st vessel in port, laden with this article, 
resort to it with all the ardour 6f impa- 
tience and competition. This first vessel 
also is entitled to a considerable premium. 
The term herring is derived from a German 
word, meaning an army, and well expresses 
the immense multitude of this fish, which, 
after wintering within tire arctic seas, where 
insect food abounds fully to the extent of 
their immense demands, direct their course 
in spring towards the south. In April they 
are generally seen olF the isles of Shetland, 
and their progress is marked by the flocks 
of birds which accompany tliem, and prey 
upon them. There are, in general, several 
columns of this mighty host, extending 
about five miles in length and three in 
breadth, and reflecting, by their advance to 
very surface of the water, that pearly 
CLU 
lustre and lively variety of colour which, in 
clear weather, give to the spectacle extra- 
ordinary interest. From the Isles of Shet- 
land they divide to the eastern and western 
shores of Great Britain ; in the former case 
passing through the English Channel, after 
visiting every gulf and creek within its limits; 
in the latter, visiting the coast of Ireland, 
and furnishing the inhabitants with a cheap 
and valuable article of subsistence. Some na- 
turalists, however, have doubted of the ex- 
tensive migrations ascribed to the herring, 
and consider the time allotted for its ac- 
complishment as totally inadequate for this 
purpose. They suppose them in winter to 
shelter themselves in the profound retreats 
of the ocean, mid amidst its soft and muddy 
bottoms, near those very shores, in tlieir 
approach to which they are first seen in 
spring. The food of the herring consists 
chiefly of sea-insects and worms, and itself 
becomes food, not only, as'before intimated, 
to various birds who follow their track with 
unceasing vigilance and voracity, but to in- 
numerable fishes also : of these the whale 
is its most formidable enemy, and thins its 
columns with the most destructive and con- 
suming havock. 
The C. pilchardus, or the pilchard. This 
is somewhat smaller than the last ; its scales 
also are larger; and its body is thicker, 
rounder, and more oily. It abounds in the 
Summer months on the coast of Cornwall, 
and in the port of St. Ives nearly two hun- 
dred and fifty millions were once inclosed 
by a single draught. The supply of this 
fish being vei-y frequently far superior to 
any regular demand, it has in some cases 
been employed merely as manure, for which 
it is found admirably applicable. 
C. alosa or shad. This is considerably 
like the pilchard; but is larger and thinner ; 
distinguishable particularly by the scales 
upon its belly, which form a sharp keel 
along it. It is found in the Mediterranean 
and in the Baltic, and ascends rivers pe- 
riodically to deposit its spawn, which it al- 
ways does in the deepest parts. The longer 
it continues in fresh water, the fatter it be- 
comes ; it feeds principally on insects and 
young fish, and can live but a few moments 
after being taken from the water. It is lit- 
tle valued for the table, being coarse and 
tasteless. It is found in the rivers of Eng- 
land, and principally in the Severn. 
C. spiattus, or sprat, resembles the her- 
ring, and might easily be taken for its 
young. There are, however, decided dif- 
ferences. During the winter months sprat* 
