DIO 
DIO 
tail, however, of the fish protrudes fi'om the 
moutli of the bird till the head is digested, 
and, in the interval, the bird is so iinweildy 
and defenceless, that it is easily destroyed 
by the natives. It quits Kanitschatka in 
August, never having been certainly known 
to build there. In Patagonia and the Falk- 
land Islands its nest is made on the ground, 
■with earth, a foot in height, and of a circu- 
lar figure. AVhile the female sits, the male 
is incessant in his assiduities to provide for 
her subsistence, and both are so tame as to 
permit any person to push them from their 
nest, and deprive them of their eggs with- 
out the slightest resistance. The hawk is 
perpetually vigilant fon the removal of the 
female, during which it darts on her nest, 
and purloins her treasure. The grey gull 
takes a more daring aim, and assails the al- 
batross itself, attacking it beneath, to pre- 
vent which, that bird, when in danger from 
this gull, flies immediately to the water, 
and seldom leaves the surface for distant 
flights, unless in the seasons of its migra- 
tion. The nests of the albatross, when 
vacated by them, are immediately occupied 
by the penguin. Albatrosses have been 
seen by voyagers at the distance of 600 
leagues from land. For the albatross, see 
Aves, Plate VI. fig. 3. 
DIONdii.V, in botany, a genus of the 
Decamii ia Monogynia class and order. Na- 
tural order of Gruinales. Essential charac- 
ter: calyx five-leaved; petals five ; capsule 
one-celled, gibbous, containing many seeds. 
There is but one species, viz. D. mucipula, 
Venus’s fly-trap, a native of North Caro- 
lina, in sw'ampy places. 
DIOPH 4.NTINE proftlems, are certain 
questions relating to square and cubic num- 
bers, and to right-angled triangles, &c. the 
nature of which were first and chiefly 
treated of by Dioirhantes in his algebra. 
In tliese questions it is chiefly intended 
to find commensurable numbers to answer 
indeterminate problems ; which often bring 
out an infinite number of incommensurable 
quantities. For example, let it be pro- 
posed to find a right-angled triangle, 
whose three sides, x, y, z, are expressed by 
rational numbers; from the nature of the 
figure it is known that z^, where 
2 denotes the hypothenuse. Now it is plain 
that X and y may also be so taken, tliat z 
shall be irrational ; for if x = 1, and y = 2, 
then is r = v' 5. 
Now the art of resolving such problems, 
consists in ordering the unknown quantity 
or quantities, in such a manner, that the 
square or higher power may vanish out of 
the equation, and tlicn by means of the 
unknown quantity in its first dimension, the 
equation may be resolved without having 
recourse to ineommensurables. e. g-. let it 
be supposed to find x, y, z, the sides of a 
right-aqgled triangle, such as will give 
= zh .Suppose 2 = .r then 
-4- = .P-j- 2 X M + ; out of which 
?/^ — 
equation vanishes, and ; 
2 u 
then 
assuming y and a equal to any numbers at 
pleasure, the sides of the triangle will be 
and the hypotlienuse x -j- a = 
y, 
y X M 
2 u 
y X vr -c „ j y — a 
— ; if a = 3, and a = 1, then 
— = 4, and a- -|- a = 5. It is evident that 
this problem admits of an infinite number 
of solutions. 
DIOPSIS, in natural history, a genus of 
insects of the order Aptera. Generic cha- 
racter : head with two inarticulate filiform 
horns, much longer than the head, at the 
tip of which are placed the eyes. There is 
but one species, viz. D. ichneumonea, which 
resembles the ichneumon, and is found in 
South America and Guinea. It is of the 
size of an ant, and very remarkable for the 
singular appearance of the eyes, which ap- 
pear seated at the tips of a p-air of long 
processes, at first sight resembling an- 
tennae. 
DIOPTRICS, the science of refractive 
vision, or that part of optics which consi- 
ders the different refractions of light in its 
pas.sing through different mediums, as air, 
water, glass, &c. and especially lenses. See 
Optics. 
DIOSCORE.'V, in botany, English yam, 
a genus of the Dioecia Hexandria class and 
order. Natural order of Sarmentaceae. 
Asparagi, Jussieu. Essential character: 
male, calyx six-parted ; corolla none. Fe- 
male, calyx six-parted ; corolla none ; styles 
three ; capsule three-celled, compressed ; 
seeds two, membranaceous. There are fif- 
teen species. These plants have usually tu- 
berous perennial roots, with twining sterns 
fr om right to left ; flowers axillary, in 
spikes or racemes. Several of these species 
are natives of the East and West Indies, 
where they are cultivated for food. 
DIOSMA, in botany, a genus of the 
Pentandria Monogynia class and order. 
Natural order of Aggregatae. Rutaceae, 
Jussieu. Essential character : corolla five- 
petalled ; nectaries five on the germ ; capsule 
three or five conjoined ; seeds veiled. There 
