D I O 
D I O 
52.5. 
0 r a 
frer, among other birds, in great abundanco. 
Their nests are made on the ground with 
earth, are round in shape, a foot in height, 
and indented at top. * The egg is larger 
than that of a goose, four inches and a half 
long, white, marked with dull spots at the 
large end ; and is thought to be good food, 
the white never growing hard with boiling. 
"While the female is sitting, the male is con- 
stantly on the wing and supplies her with 
food: during this time they are so tame as 
to suffer themselves to be pushed oil the 
nest while their eggs are taken from tliem ; 
but their chief destruction arises from- the 
hawk, which, the moment the female gets 
off the nest, darts on it, and flies away with 
the egg. The albatross itself likewise lias its 
enemy, being greatly persecuted, while on 
the wing, bv the dark grey gull called skua. 
8. The demersa, has no quill-feathers on the 
wings ; arid the feet have four toes, connect- 
ed together by a membrane. It is the black 
penguin of Edwards, about the size of a 
goose, and is found at the Cape of Good 
Hope. It is an excellent swimmer and diver; 
but hops and flutters in a strange awkward 
manner on the land, and, if hurried, stumbles 
perpetually, and frequently runs for some 
distance like a quadruped, making use of 
the wings instead of legs, till it recovers its 
upright posture ; crying out at the same 
time like a goose, but in a much hoarser 
voice. It is said to climb some way up the 
rocks in order to make its nest; in doing 
which, it lias been observed to assist with 
its bill. The eggs are two in number, white, 
as large as those of a duck, and reckoned 
delicious eating ; at least they are thought 
so at the Cape, where they are brought in 
great numbers for that purpose. At this 
place the birds are often kept tame ; but in 
general they do not survive the confinement 
many months. 
DlON/EA muscipula, or Venus’s fly- 
trap, in botany, a newly discovered sensitive 
plant, in the construction of which nature 
seems to have had some view towards its 
nourishment, in forming the upper joint of 
its leaf like a machine to catch food ; and 
placing upon the middle of it the halt for 
the unhappy insect that becomes its prey. 
Many minute red glands- that cover its inner 
surface, and which perhaps discharge some 
sweet liquor, tempt the poor insect to taste 
them ; and the instant these tender parts are 
irritated by its feet,, the two lobes rise up, 
grasp it fast, lock the two rows of spines to- 
gether, and squeeze it to death. And fur- 
ther, lest the strong efforts for life, in the 
creature thus taken, should serve to disen- 
gage it, three small erect spines are fixed 
Hear the middle of each lobe among the 
glands, that effectually put an end to all its 
struggles. Nor do the lobes ever open again, 
while the dead animal continues there. But 
it is nevertheless certain, that the plant can- 
not distinguish an animal from any other 
substance ; for if we put a straw or a pin be- 
tween the lobes, it will grasp it full as fast 
as if it was an insect. The plant is one of 
the monogynia order, in the decandria class. 
It grows in America, about 35 deg. N. lat. 
in wet shady places, and flowers in July and 
August., The largest leaves are about three 
inches long, and an inch and a half across 
the lobes: the glands of those exposed to the 
sun are of a beautiful red colour ; but those 
in the shade are pale and inclining to green. 
The roots are squamous, sending forth but 
few fibres, and arc perennial. The leaves 
are numerous, inclining to bend downwards, 
and are placed in a circular order ; they are 
jointed and succulent; the lower joint, which 
is a kind of stalk, is fiat, longish, two-edged, 
and inclining to heart-shaped. In some va- 
rieties they are serrated on the edges near 
the top. The upper joint consists ot two 
lobes ; each lobe is of a semi-oval form, with 
the margins furnished with stiff hairs like 
eyebrows, which embrace or lock in eacli 
other when they close : this they do when 
they are inwardly irritated. The upper sur- 
faces of these lobes are covered with small 
red glands ; each of which appears, when 
highly magnified, like a compressed arbutus- 
berry. Among the glands, about the middle 
of each lobe, are three very small erect 
spines. When the lobes inclose any sub- 
stance, they never open again while it con- 
tinues there. If it can be pushed out so as 
not to strain the lobes, they expand again ; 
but if force is used to open them, so strong 
has nature formed the spring of their fibres 
that one of the lobes will generally snap off 
rather than yield. The stalk is about six 
inches high, round, smooth, and without 
leaves; ending in a spike of flowers. The 
flowers are milk-white, and stand on foot- 
stalks, at the bottom of which is a little paint- 
ed bractea or flower-leaf. The soil in which 
it grows, as appears from what comes about 
the roots of the plants when they are brought 
over, is a black light mould, intermixed 
with, white sand, such as is usually found in 
our moorish heaths. Being a swamp plant, 
a north-east aspect will be properest for it at 
first, to keep it from the direct rays of the 
sun ; and in winter, till we are acquainted 
with what cold weather it can endure, it will 
be necessary to shelter it with a bell-glass, 
such as is used for melons. This should be 
covered with straw' or a mat in hard frosts. 
By this means several of these plants have 
been preserved through the winter in a very 
vigorous state. Its sensitive quality will be 
found in proportion to the heat of the weather, 
as well as the vigour of the plant. Our sum- 
mers are not warm enough to ripen the seed ; 
or possibly we are not sufficiently acquainted 
with the culture of it- See Plate Nat. Hist, 
fig. 170. 
DiOPHANTINE problems, in mathe- 
matics, certain questions relating to square 
and cube numbers, and right-angled tri- 
angles, &c. the nature of which was deter- 
mined by Diophantus, a mathematician of 
Alexandria, who is believed to have lived 
about the third century. In these questions it 
is endeavoured to find commensurable numb- 
ers to answer indeterminate problems ; which 
bring out an infinite number of incommen- 
surable quantities. For example, it is pro- 
posed to find a right-angled triangle, 
whose sides x, y, z, are expressed by com- 
mensurable numbers ; it is known that 
x 2 -\ -y 2 z=.z, z being tire supposed hypothe- 
nuse. But it is possible to assume x and y 
so, that z .will be incommensurable; for if 
x zzz 1 , and y —2, z — 5. Tly art of re- 
solving such problems consists in managing 
the unknown quantity or quantities in such a 
manner, that the square or higher power may 
vanish out of the equation, and then by 
means of the unknown quantity in its first 
dimension, the equation may be resolved- 
without having recourse to inconmiensurables. 
For example, in the equation above, v 2 y 1 
— z z , suppose z — x -f- n, then is x 2 -j- y ~z 
x 2 _}_ 2 xu -j- u 2 , out of which equation x 2 vanishes, 
and then it is / =. 2 xu -j- u, which gives x = 
•t — Hence, assuming- y and it equal to any 
2ll 
numbers at pleasure, the thVee sides of the tr& 
* 2 2 12 
y" — u y -4- u ... 
angle will be y, — - , and — - — , winch are 
° 2 u 2 « 
all rational whenever y and u are rational. For. 
y — 
2ti 
example, if y = 3, and u ~ 1, then 
y 2 4- " 2 T • 
— 4, and -v -j- u, or — A. — , = .5. It is evident 
that this problem admits of infinite numbers of 
solutions (see Sanderson’s Algebra), as- y or # 
may be assumed infinitely various. 
DIOPSIS, a genus of the vermes, class and 
of the diptera order. Head with two inar- 
ticulate filiform horns much longer than 
the head, at the tip of which are placed the 
eyes. It inhabits South America and Guinea, 
and resembles the ichneumon. d here is 
but a single species. 
DIOPTRICS,, the science of refractive vi- 
sion ; or that part of optics which considers 
the different refractions ot light in its passing 
through different mediums, as air, water, 
glass, &c. and especially lenses. See Optics . 
D IOSCO REA, in botany, a genus of die 
hexandria order, in the dioecia class of plants ; 
and in the natural method ranking under the 
11th order, sarmentaceac. The male calyx is 
sexpartite, there is no coitilla : the female calyx 
is sexpartite ; no corolla three styles ; the 
capsule trilocular and compressed ; and there- 
are two membranaceous seeds. There are 
15 species, of which the only remarkable one 
is the sativa or yam. This has slender stalks, 
which trail upon the ground and extend a 
great way : these frequently put out roots 
from their joints as they lie upon the ground, 
by which the plants are multiplied. The 
roots are eaten by the inhabitants of both the* 
Indies; and are particularly serviceable in 
the West India islands, where they make 
the greatest part of the negroes’ food. The 
plant is supposed to have been brought from 
the East to the West Indies ; for it has ne- 
ver been observed to grow wild in any part 
of America ; but in the island of Ceylon, 
and on the coast of Malabar, it grows in the- 
woods, and there are in those places a great 
variety of sorts. It is propagated by cutting 
the root in pieces, observing to preserve an 
eye in each, as is practised in planting po- 
tatoes. One plant will produce three or four- 
large roots. The skin of these roots is pretty 
thick, rough, unequal, covered with many 
stringy fibres or filaments, and of a violet co- 
lour approaching to black. The inside is 
white, and of the consistence of red beet. It 
resembles the potatoe in its mealiness, but 
is of a closer texture. When raw, the yams 
are viscous and clammy : when roasted or 
boiled, they afford very nourishing food; 
and are often preferred to bread by the in- 
habitants of the West Indies, on account of 
their lightness and facility of digestion. When 
first dug out of the ground, the roots are 
placed in the sun to dry : after which, they 
are either put into sand, dry garrets, or 
casks ; where if kept from moisture, they 
may be preserved for years, without being 
spoiled or diminished in their goodness. The 
