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bottom of the box ; and the arbor of move- 
able wheels to go through the top of the 
box, on a proper height, on the top of which 
is to be placed a round ball, gilt with gold, 
to represent the sun. On each of the move- 
able wheels is to be fixed a socket, or tube, 
ascending above the top of the box, and 
having on the top a wire fixed, and bent at 
a proper distance into a right angle upwards, 
bearing on the top a small round ball, re- 
presenting its proper planet. 
If then on the lower part of the arbor of 
fixed wheels is placed a pinion of screw- 
teeth, a winch turning a spindle with an 
endless screw, playing in the teeth of the 
arbor, will turn it with all its wheels ; and 
these wheels will move the others about 
with their planets, in their proper and re- 
spective periods of time, very exactly. For, 
while the fixed wheel CK moves its equal 
CP ouce round, the wheel AM will move 
AN a little more than four times round, and 
so will nicely exhibit the motion of Mercury; 
and the wheel EG will turn the wheel ES 
about _J — round, and so will truly repre- 
29,5 
sent the motion of Saturn, and the same is to 
be observed of all the rest. 
O IP TEG I A, a genus of the class and order 
triandria monogynia. The calyx is five- 
leaved ; corolla none ; capsule one-celled ; 
seeds many. There are two species, trailing 
plants of Spain and Italy. 
ORTHOGRAPHY, that part of grammar 
which teaches the nature and affections of 
Letters, and the just method of spelling or 
writing. 
Orthography, in geometry, the art of 
drawing or delineating the fore-right plan of 
any object, and of expressing the heights or 
elevations of each part. It is called ortho- 
graphy, from its determining things by per- 
pendicular lines falling on the geometrical 
plane. 
Orthography, in architecture, the ele- 
vation of a building. 
Orthography. Sec Perspective. 
ORTOLAN. See Emberiza. 
ORYZA, rice, a genus of the digvnia 
order, in the hexandria class of plants ; and 
in the natural method ranking under the 4th 
order, gramma. The calyx is a bivalved 
imifiorous glume ; the corolla bivalved, near- 
ly equal, and adhering to the seed. There 
is but one species, namely, the sativa or com- 
mon rice. This plant is greatly cultivated 
in most of the Eastern countries, where it is 
the chief support of the inhabitants ; and 
great quantities of it are brought into Eng- 
land and other European countries every year, 
where it is much esteemed for puddings, 
&c. it being too tender to be produced in 
these northern countries without the assist- 
ance of artificial heat ; but from some seeds 
which were formerly sent to Carolina there 
have been great quantities produced, and it 
is found to succeed there as well as in the 
Eastern countries. 
This plant grows upon moist sods, where 
the ground can be llowed over with water 
after it is come up. 
Rice is the chief commodity and riches of 
Damieta in Egypt, and L)r. Hasselquist 
gives the following description of the mariner 
in which they dress and separate it from the 
Rusks, “ It is pounded by hollow iron pes- 
Vol II. 
[ ties of a cylindrical form, lifted up by a 
wheel worked by oxen. A person sitting 
between the two pestles, pushes forward the 
rice when the pestles are rising; another 
sifts, winnows, and lays it under the pestles. 
In this manner they continue working it un- 
til it is entirely free from chaff and husks. 
YV hen clean, they add a thirtieth part ol 
salt, and pound them together; by which 
the rice, formerly grey, becomes white. Af- 
ter this purification, it is passed through a 
fine sieve to part the salt from the rice; and 
then it is ready for sale.” Damieta sells 
every year 60,800 sacks of rice, the greatest 
part of which goes to Turkey, some to Leg- 
horn, Marseilles, and Venice. 
Rice, according to Dr. Cullen, is prefer- 
able to all other kinds of grain, both for 
largeness of produce, quantity of nourish- 
ment, and goodness. This, he says, is plain 
from macerating the different grains in wa- 
ter ; for, as the rice swells to the largest size, 
so its parts are more intimately divided. 
Rice is said to affect the eyes; but this is 
purely prejudice. Thus it is alleged a par- 
ticular people of Asia, who live on this grain, 
are blind-eyed ; but if the soil is sandy, and 
not much covered with herbage, and the 
people are much employed in the field, this 
affection of their eyes may be owing to the 
strong reflection of the rays of light from 
this sandy soil ; and our author is the more 
inclined to this opinion, because no such ef- 
fect is observed in Carolina, where rice is 
commonly used. 
OS HECK I A, a genus of the octandria mo- 
nogynia class and order. The cal. is four- 
cleft ; cor. four and five-petalled ; stani. 
eight or ten; anthers beaked ; caps, inferior, 
four-celled. There is one species, a trifling 
plant of China. 
OSCILLATION, in mechanics, the vi- 
bration, or reciprocal ascent and descent, of 
a pendulum. See Pendulum. 
It is demonstrated, that the time of a com- 
plete oscillation in a cycloid, is to the time 
in which a body would fall through the axis 
of that cycloid, as the circumference of a 
circle to its diameter; whence it follows, 1. 
That the oscillations in the cycloid are all 
performed in equal times, as being all in the 
same ratio to the time in which a body 
falls through the diameter of the generating 
circle. 2. As the middle part of the cycloid 
may be conceived to coincide with the ge- 
nerating circle, the time in a small arch of 
that circle will be nearly equal to the time 
in the cycloid; and hence the reason is evi- 
dent, why the times in very little arches are 
equal. 3. The time of a "complete oscilla- 
tion in any little arch of a circle, is to the time 
in which a body would fall through half the 
radius, as the circumference of a circle, to 
its diameter ; and since the latter time is 
half the time in which a body would fall 
through the whole diameter, or anv chord, 
it follows that the time of an oscillation in 
any little arch, is to the time in which a 
body would fall through its chord, as the 
semicircle to the diameter. 4. The times 
of the oscillations in cycloids, or in small 
arches of circles, are in a sub-duplicate ratio 
of the lengths of the pendulums. 5. But if 
the bodies that oscillate are acted on by un- 
equal accelerating forces, then the oscillation 
will be performed in times that are to one 
S s 
another in the ratio compounded of the di- 
rect subduplicate ratio of the lengths of the. 
pendulums, and inverse subduplicate ratio 
of the accelerating forces. Hence it appears 
that if oscillations of unequal pendulum- are 
performed in the same time, the accelerating 
gravities of these pendulums must be as their 
lengths; and thus we conclude, that the. 
force of gravity decreases as you go to- 
wards the equator, since we find that the 
lengths of pendulums that vibrate seconds 
arc always less at a less distance from tire 
equator. 6. The space described by a fall- 
ing body in any given time, may be exactly 
known ; for finding, by experiments, what 
pendulum oscillates in that time, the half 
of the pendulum will be to the space 
required, in the duplicate ratio of the dia- 
meter of a circle to the circumference. 
Centre of Oscillation. See Centre. 
OSMITES, a genus of the class and order 
syngenesia polygamia frustranea. The cal. 
is imbricate, scariose ; cor. of the ray ligu- 
iate ; down obsolete; recept. chaffy. There 
are four species, shrubs of the Cape. 
OSMUNDA, moon-zuort ; a genus of thb 
order of filices, in the crvptogamia class of 
plants. There are twenty-seven species; 
the most remarkable of which is the regalis, 
osmund-royal, or flowering fern. This is a 
native of Britain, growing in putrid marshes. 
Its leaf is doubly winged, bearing bunches of 
flowers at the ends. The root boiled in 
water is very slimy ; and is used in the north 
to stiffen linen instead of starch. Some of 
the leaves only bear flowers. 
OSSIFICATION, the formation of bones. 
See Concretions. 
OS'l EOLOGY. See Anatomy. 
OS 1 EOSPEUMl >M, a genus of the class 
and order syngenesia polygamia necessaria. 
1 he cal. is simple, in two rows, mam-leav- 
ed, almost equal ; seeds globular, coloured, 
bony; down none ; recept. naked. There 
are 17 species, shrubs of the Cape. 
OS I RAC ION, in ichthvologv, a genus 
of the branchiostegous order of ‘fishes^ of a 
globose, oval, or ovato-quadvangular figure j 
the skin is always very firm and hard ; and 
is in some species smooth, in others entiiely 
covered with spines ; and, finally, in some 
the spines entirely occupy only particular 
places ; there are lio belly-fins, aiid the others 
are live in number, viz. two pectoral or la- 
teral fins, one on the back, the pinna ani, 
and the tail. There are 12 species of this 
genus : the triqueter has a triangular body 
unarmed; inhabits India; the back appear- 
ing as if covered with rhombic marks cut 
transversely. The quadricornus, with frontal 
and subcaudal spines, inhabits India and 
Guinea. 
Os trac ion, trunk-fish, a genus of fishes, 
of the order nantes; tire generic charac- 
ter is, teeth pointing forwards, cvlindric, 
rather blunt ; body mailed by a bony co- 
vering. 
1. Ostracion triqueter, triquetral trunk- 
fish ; the ostracions or trunk-fishes are so 
strikingly distinguished by their bony crust 
or covering, that no difficulty can arise to the 
ichthyological student in referring them to 
their proper genus. The investigation of the 
species however demands a greater degree 
of attention, and such is the similarity be- 
tween some of these, that it remains clcmhu 
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