CIl A 
ciiain of four pendants, so equally, and at 
the same time so firmly connected, that 
the eye takes the whole to consist of one 
piece. 
Chain, in surveying, a measure of length, 
made of a certain number of links of iron- 
wire, serving to take the distance between 
two or more places. Gunter’s chain is of 100 
such links, each measuring 7^® inches, and 
consequently equal to 66 feet, or four poles. 
When you are to measure any line by this 
chain, you need have regard to no other 
denomination than chains and links, which 
are to be set down with a full point be- 
tween them. Thus, for instance, if the 
side of a close is found to be 10 chains 14 
links, it must be set down thus, 10.14. But 
if the links be under 10, a cypher must be 
prefixed ; thus 10 chains 7 links, must be 
set down 10.07. 
Then if the field be a square or parallelo- 
gram, if you multiply the length expressed 
in chains and links, by the breadth ex- 
pressed in the same manner, and cut off 
five figures from the product, those towards 
the left hand will be acres ; then multiply 
the separated figures by four, cutting off 
-the same number of figures, and you will 
have the roods or quarters of an acre ; and 
lastly multiply the remaining figures by 40, 
cutting off five as before, and you will have 
the square perches. See Surveying. 
Chain s, in a ship, those irons to which the 
shrouds of the masts are made fast to the 
chain walls. 
Chain walls, in a ship, the broad tim- 
bers which are made jetting out of her sides, 
to which the shrouds are fastened and 
spread out, the better to secure the masts. 
Chain shot, two bullets with a chain 
between them. They are used at sea to 
shoot down yards or masts, and to cut the 
shrouds or rigging of a ship. 
Chain pump. See Pump. 
CHALCEDONY, in mineralogy, a spe- 
cies of the flint genus : of which there are, 
according to Werner, two subspecies, viz. 
the common chalcedony and the carnelian : 
the colour of the former is grey in all its 
shades. It is commonly semi-transparent, 
harder than flint, brittle, difficultly frangi- 
ble ; and the specific gravity, according to 
Kirwan, is about 2.6. Infiisible before the 
blow-pipe. It is found mostly in balls, in 
amygdaloid, also in angular pieces and 
veins, in porphyry and amygdaloid. The 
cubic variety occurs in Transylvania, and 
(he other varieties in Iceland, the Feme 
islands, Silesia, Saxony, Siberia, Corn- 
Scotland, fee. It is susceptible of 
CH A 
a fine polish, and is employed as an article 
of jewelry. It derives its name from 
Chalcedon, in Asia, where it was first 
found. Onyx is considered as the most va- 
luable variety of this species, and on ac- 
count of its being capable of receiving a 
high polish is very much prized. It is prin- 
cipally cut in bas relief work, and tbe finest 
specimens for that purpose are brought from, 
the East Indies. The dendritic variety is 
named mocha stone, being brought, origi- 
nally, as was supposed, from Mocha on the 
Red Sea ; but it is now generally under- 
stood that the word mocha is a corruption 
from the German word mocks, which sig- 
nifies moss ; and it is affirmed that no stone 
of the kind is found near Mocha. 
The principal colour of the carnelian is 
blood red, of all degrees of intensity ; from 
this it passes into milk-white, and also into 
a kind of yellow. Semi-transparent; and 
in many other of its characters it agrees 
with the common chalcedony. It is found 
accompanying agate, and, in general, has the 
same geognostic situation as chaledony. 
The fine oriental varieties occur in rolled 
pieces. The most beautiful carnelian is 
brought from Arabia and Hindostan ; it is 
also found in different parts of Europe, and 
is used for seals, bracelets, crosses, and 
other Ornaments. 
CHALCIS, in natural history, a genus of 
insects of the order Hymenoptera : mouth 
with a horny compressed jaw ; feelers four 
equal ; antennae short, cylindrical, fusiform ; 
the first joint a little thicker ; thorax gib- 
bous, lengthened behind in the place of a 
scutel ; abdomen rounded and slightly pe- 
tiolate.. There are eleven species. 
CHALDRON, a dry English measure, 
consisting of thirty-six bushels, heaped up 
according to the sealed bushel kept at 
Guildhall, London : but on ship-board, 
twenty-one chaldron of coals are allowed to 
the score. 
CHALK, in natural history, a species of 
Calk, which see. 
Chalk, where it is found at all, is the pre- 
ponderating substance, and may therefore 
be considered as characterizing a peculiar 
species of mineral formation. It is perhaps 
the most recent of all the varieties of cal- 
careous carbonates ; it occurs in strata for 
the most part nearly horizontal, alternating 
with thin layers of flint nodules, and with 
the same irregularly dispersed through its 
substance : it contains in abundance the 
relics of marine organized bodies, such as 
echinites, glossopetrae pcctinites, &c. and 
also not unfrequently the hard parts of 
