C O 11 
COR 
C 0- R 
1 mperfcct corundum . 
From the 
From 
F rom 
From 
Carnatic 
Malabar, 
China. 
Ava. 
Silica 5.0 
'7.0 
5.25 
6.5 
Alumina 91.0 
80.5 
86.50 
87.0 
Iron ].5 
4.0 
6.50 
4.5 
Loss 2.5 
2.5 
1.75 
2.0 
100.0 
100.0 
100.00 
100.0 
Perfect corundum. 
Silica 
Alumina 
Iron 
Loss 
Blue, or 
Red, or 
sapphire. 
oriental ruby 
5.25 
7.0 
92.00 
90.0 
1.00 
1.2 
1.75 
1.8 
100.00 
100.0 
Mi. Klaproth s analysis of sapphire differs 
a httie from the above, but his analysis of im- 
perfect corundum agrees with it. 'He found 
Lie sapphire composed of 
98.5 alumina 
1.0 o.xyd of iron 
0.5 lime 
100.0 
CORKS, Omer, Homer, or Chomer in 
tlie Jewish antiquities, a measure containing 
10 baths, or 75 gallons and 5 pints, as a mea- 
.suic tor things liquid, and 32 pecks and 1 
.pint, as a measure for things dry. 
LUSCATION, a glittering or gleam 
ot light issuing from any thing, it is chiefly 
used for the electrical fluid when rendered 
visible, as in a flash ot lightning, See. There 
aie methods of producing artificial corusca- 
t ions, or sparkling fiery meteors, which will 
be visible not only in the dark but in the dav- 
timef 
CORA US, the raven or crow kind, in or- 
nithology; a genus of birds of (he order of 
pica-, the distinguishing characteristics of 
w nu h aie these: the beak is convex and cul- 
trated; the nostrils are covered with bristly 
feathers; the tongue is forked and cartilagi- 
nous; and the feet are of the walking kind, 
i he species are 19, the most remarkable of 
winch are (see Plate Nat. Hist. fig. 144.): 
1.1 be corax, or raven ot English authors, 
weighs three pounds, and is about two feet 
two indies in length; the colour is black, 
finely glossed with a rich blue, the belly ex- 
cepted, which is of a dusky colour. They 
aie very docile birds, and may be trained up 
to fowling like hawks, or to fetch and carry 
spaniels ; they may be taught to speak 
hke parrots ; and, what is most extraordinary 
° a » they may be taught to imitate the hu- 
man voice in singing. They have a great 
piopensity to pilfer, often hiding things of 
value, to the great loss ot the owner, without 
use to themselves. They frequent the neigh- 
bourhood of great towns/ where they are use- 
mi in devouring the carcases and filth which 
would otherwise prove a nuisance. They, 
however, also destroy many living animals; 
such as rabbits, young ducks, and chickens, 
and not (infrequently lambs which have been 
mopped in a weak state. In clear weather 
they fly in pairs to a great height, making a 
ueep loud noise, different from the common 
croaking. Their scent is remarkably good, 
and they are very long-lived. The raven 
onflds her nest early in the spring, laying 
1 five or six eggs, of a pale blueisli-grcen co- 
lour, spotted with brown. 
2. The corone, or carrion-crow, in the 
form of its body agrees with the raven ;' also 
m its food, which is carrion and other filth. 
It will also cat grain and insects; and like 
the raven will pick out the eyes of animate: 
whence it was formerly distinguished from 
the rook, which feeds entirely on grain and 
insects, by the name ot the gor, or gor-crow. 
Virgil says that its croaking forebodes rain; 
“ 1 urn cornix plena pluviam vocat improba 
voce.” It was also thought a bird of bail 
omen, especially if it happened to be seen on 
the left hand: “ Sicpe sinistra cava praxlixit 
ab ilice cornix.” England breeds more of 
this kind of birds than any other country in 
Europe. But though the crow abounds in 
Britain, it is so rare in Sweden, that Linnaeus 
speaks of it only as a bird that he once knew 
killed there. It lays the same number of 
eggs as the raven, and of the same colour. 
Immediately after deserting their young they 
go in pairs. Both these birds are often found 
white or pied, an accident that befals black 
birds more frequently than any others. Mr. 
Pennant says, he has observed one entirely 
of a pale-brown colour, not only in its plu- 
mage, but even in its bill and feet. The 
crow weighs about 20 ounces. Its length is 
18 inches; its breadth two feet two inches. 
3 The frugilegus, or rook, is the corvus of 
Virgil; no other species of this kind being 
gregarious. It differs not greatly in its form 
from the carrion-crow : the most remarkable 
difference is in (he nostrils and root of the 
bill; which parts in the crow are well clothed 
with feathers, but in the rook are bare, or 
covered only with some bristly hairs. This 
arises from its thrusting the bill into the 
earth continually, after" the various worms 
and eruca: of insects, on which it feeds ; for 
it does not live on carrion, like the last species 
or the raven. Besides insects, it also feeds 
on all sorts of grain, to some inconvenience 
perhaps to the husbandman, but no doubt lie 
is doubly repaid by the good done to him in 
extirpating the maggot of the chafer-beetle, 
which in some seasons destroys} whole crops of 
corn by feeding on the roots. The rook is a 
gregarious bird, sometimes being seen in im- 
mense flocks, so as almost to darken the air. 
These flights they regularly perform morning 
and evening, except in breeding-time, when 
the daily attendance of both male and female 
is required for the use of intubation, or feed- 
ing the young; for it is observed that they do 
both by turns. As these birds are apt to 
form themselves into societies, such places as 
they frequent during the breeding-time are 
called rookeries; and they generally choose 
a large clump of the tallest trees for 'this pur- 
pose, but make so great a litter, and such a 
perpetual chatter, that nothing but habit and 
a length of time can reconcile one to the 
noise. The eggs are like those of crows, but 
less, and the spots larger. They begin to 
build in March, and after the breeding- sea- 
son forsake their nest-trees, going to roost 
elsewhere, but have been observed to return 
to them in August. In October they repair 
their nests. In Britain they remain the 
whole year; yet we are tola that both in 
France and Silesia they are birds of passage. 
4. The cornix, or Royston crow, in its ha- 
bits resembles the rook, feeding on insects, 
and flying together in great flocks ; but is 
Ail 
easily distinguished by its plumage ; its back, 
breast, and belly, being ash-colour, inclining 
to light-blue, and consequently much hand- 
somer; it is also rather larger than the rook, 
weighing 22 ounces. In England it is a bird 
ot passage, visiting that kingdom in the be- 
ginning of winter, and leaving it with the 
woodcocks, hi the maritime parts they feed 
on crabs and shell-iish. They are very com- 
mon in Scotland; in many parts of the' liigh- 
lands, and in all the Hebrides, Orkneys, and 
Shetland*, it is the only species of genuine 
crow, the carrion and rook being unknown 
there. ^ It breeds andcontihues in those parts 
tne whole year round. In the Highlands 
they breed indifferently in all kinds of trees; 
lay six eggs ; have a shriller note than the 
common crows; are much more mischiev- 
ous; pick out the eyes of lambs, and even of 
horses when entangled in bogs. T hey are, 
therefore, in many places proscribed, and re- 
wards given for killing them. For want of 
other food these birds will eat cranberries or 
other mountain berries. 
5. I he dauricus, or white-breasted crow, 
is in length about 12 inches; the bill is black; 
(lie head and throat are black, glossed with 
l):ue; the neck and breast white; the rest of 
the body, wings, and tail, blue-black ; the legs 
of a lead-colour; the claws black. Pallas 
describes the same species, which he says 
came early in the spring in great flights from 
China, and the southern Mongols country, 
into the purls about the lake Baikal, but most 
frequent about the towns and villages on the 
riv er Lena, in which part the jackdaws and 
Royston crows are very seldom seen. They 
live chiefly on insects. J 
<3. The monedula, or jackdaw, weighs 
nme ounces; the length 13 inches, the breadth 
28. The head is large in proportion to its 
body; which Mr. YVillughby says, argues 
him to be ingenious and crafty. It is a docile 
and loquacious bird. Jackdaws breed in 
steeples, old castles, and in high rocks, lay- 
ing live or six eggs. Sometimes they have 
been known to breed in hollow trees near a 
rookery, and join those birds in their foraging 
parties. In some parts of Hampshire they 
make their nests in rabbit-holes. They also 
build in the interstices between the upright 
and transum stones of Stonehenge; a proof 
of the prodigious height of that stupendous 
antiquity, for their nests are placed beyond 
the reach of the shepherd-boys, who are al- 
unvs idling about this spot. I hey are gre- 
garious birds, and feed on insects, grain, and 
seeds. These birds are frequently brought 
up tame; they have a practice of hiding that 
part ot their food which they cannot eat" ; and 
often, along with it, they secrete small valu* 
aides, sometimes occasioning injurious sus- 
picions ot theft in servants or others not 
guilty. 
7. The glandarius, or jay, is one of the 
most beautiful of British birds. The weight 
is between six and seven ounces; the lenotli 
13 inches. The forehead is white streaked 
with black; the head is covered with very 
long feathers, which it can erect at pleasure 
into the form of a crest ; the whole neck 
back, breast, and belly, are of a faint purple 
dashed with grey; the covert-feathers of the 
wings are ot the same colour. The first 
quill-feather is black ; the exterior webs of 
the nine next are ash-coloured ; the interior 
webs dusky ; the six next are black, but the- 
