512 
OPT 
O R C 
O It C 
near to it as to be within the sphere of that ‘ 
power 'pvhich the body possesses, it must ne- 
c .•ssarilv suffer a change in its direction. Ac- 
tual experiments confirm, the truth of this po- 
sition ; and to the change in the direction of 
a particle of light, owing to its nearness to a 
body, we give the name of inflection. 
From one of these experiments, made by 
sir Isaac Newton, the whole of this subject 
will be easily understood. At the distance of 
two or three feet from tire window of a dark- 
ened room, in which was a hole three-fourths 
of an inch broad, to admit the light, he placed 
a black sheet of pasteboard, having in the 
middle a hole about a quarter of an inch 
square, and behind the hole the blade of a 
sharp knife, to intercept a small part of the 
light which would otherwise have passed 
through the hole. The planes of the paste- 
board and blade were parallel to each other ; 
and when the pasteboard was removed at 
such a distance from the window, as that all 
the light coming into the room must pass 
through the hole in the pasteboard, he re- 
ceived what came through this hole on a 
piece of paper two or three feet beyond the 
knife, and perceived two streams of faint 
light shooting out both ways from the beam 
of light into the shadow. As the brightness of 
the direct rays obscured the fainter light, by 
making a hole in his paper he let them pass 
through, and had thus an opportunity of at- 
tending closely to the two streams, which 
were nearly equal in length, breadth, and 
quantity of light. That part which was 
nearest to the sun’s direct light was pietty 
strong for the space of about a quarter of an 
inch, decreasing gradually till it bedame im- 
perceptible ; and at the edge of the knife it 
subtended an angle of about twelve, or, at 
most, fourteen degrees. 
Another knife was then placed opposite to 
the former, and he observed, that when the 
distance of their edges was about the four- 
hundredth part of an inch, the stream divid- 
ed in the middle, and left a shadow between 
the two parts, which was so dark, that all 
light passing between the knives seemed lo 
be bent aside to one knife or the other ; as 
the knives were brought nearer to each 
oilier, this shadow grew broader, till upon 
the contact of the knives the whole light dis- 
appeared. 
Pursuing his observations upon this ap- 
pearance, lie perceived fringes, as they may 
be termed, of different-coloured light, three 
made on one side by the edge of one knife,, 
and three on the other side by tile edge of 
the other ; and thence concluded, that as in 
refraction the rays of light are differently 
acted upon, so are they at a distance from 
bodies by inflection ; and by many other ex- 
periments of the same kind lie supported his 
position, which is confirmed by all subse- 
quent experiments. 
We may naturally conclude, that from this 
property of inflection some curious changes 
will be produced in the appearances of exter- 
nal objects. If we take a piece of wire of a 
less diameter than the pupil of the eye, and 
place it between the eye and a distant object, 
the latter will appear magnified (Plate III. 
fig. 21). Let A be a church-steeple, B the 
eye, C the wire. The rays by which the 
steeple would have been otherwise seen are 
intercepted by the, wire ; and it is now seen 
by inflected rays, which make a greater an- 
gle than the direct rays, and consequently 
the steeple will be magnified. 
In nearly shutting the eyes, and looking at 
a candle, there appear rays of light extend- 
ing from it in various directions, like comets’ 
iaiis ; for the light, in passing through the 
eye-lashes, is inflected ; and consequently 
many separate beams will be formed, di- 
verging from the luminous object. The 
power of bodies to inflect the rays of light 
passing near to them will produce different 
effects, according to the nature of the rays 
acted upon ; consequently a separation will 
take place in the differently refrangible rays, 
and those fringes which were taken notice 
of by sir Isaac Newton will appear in other 
objects which are seen by the means of in- 
flected rays. From considering thus the ac- 
tion of bodies upon light, we come to this ge- 
neral conclusion, for which we are indebted 
to our great philosopher : that light, as well 
as all other matter, is acted upon at a dis- 
tance ; and that reflection, refraction, and 
inflection, are owing to certain general laws 
in the particles of matter, which are equally 
necessary for the preservation of the beauti- 
ful harmony in the objects nearest to us, and 
to produce by their joint action that great law 
by which the greater bodies in their system 
are retained in their respective orbits. 
OPTION. Every bishop, whether creat- 
ed or translated, is bound immediately after 
confirmation, to make a legal conveyance to 
the archbishop of the next avoidance of such 
dignity or benefice belonging to the see, as 
the said archbishop shall choose, which is 
therefore called an option. 
OR, in heraldry, denotes yellow, or gold- 
colour. See Heraldry. 
ORANG E. See Citrus. 
ORBICULARIS. See Anatomy. 
ORBIT. See Astronomy. 
ORCHARD, a plantation of fruit-trees. 
In planting an orchard great care should be 
taken that the soil is suitable to the trees 
planted in it ; and that they are procured 
from a soil nearly of the same kind, or rather 
poorer than that laid out for an orchard. As 
to the situation, an easy rising ground, open 
to the south-east, is to be preferred. Mr. 
Miller recommends planting the trees four- 
score feet asunder, but not in regular rows ; 
and would have the ground between the trees 
plowed, and sown with wheat and other crops, 
in the same manner as if it was clear from 
trees ; by which means the trees will be more 
vigorous and healthy, will abide much longer, 
and produce better fruit, if the ground has 
been pasture, the green sward should be 
plowed in the spring before the trees are 
planted ; and if it is suffered to lie a summer 
fallow, it will greatly mend it, provided it is 
stirred two or three times to rot the grass, 
and prevent the growing of weeds. At Mi- 
chaelmas it should be plowed pretty deep, in 
order to make it loose for the roots of the 
trees, which if the soil is dry, should be 
planted in October ; but if it is moist, the be- 
ginning of March will be a better season. If 
several sorts of fruit-trees are to be planted 
on the same spot, you should observe to 
plant the largest-growing trees backwards, 
and so proceed to those of less growth, con- 
tinuing the same method quite through the 
whote plantation ; by which means the sun 
and air will more easily pass through the 
whole orchard. When you have planted the 
frees, you should support them with stakes, 
to prevent their being blown cut of the 
ground by the wind ; and the following 
spring, if the season should prove dry, cut a 
quantity of green turf, and lay it about the 
roots, with the grass downwards ; by which 
means a great expence of watering will be 
saved, and after the first year they will be 
out of danger. Whenever you plow the 
ground betwixt these trees, you must be 
careful not to go too deep amongst their 
roots, which would greatly damage the trees ; 
but if \ ou do it cautiously, your stirring the 
face ot the ground will be of great service to 
them : though you should observe, never to 
sow too near the tree, nor to suffer any great 
rooting weeds to grow about them ; be- 
cause this would starve them, by exhaust- 
ing the goodness of the soil, which every 
two or three years should be mended with j 
dung or other manure, I hese trees, after j 
they are planted out, will require no other 
pruning besides cutting oft" their bad branches, 
or such as cross each other. 
ORCTilS,/or//-A'ffwcw, a genus of the gy- 
nandria diandria class of plants, the corolla 
of which is of a cornicuiated form ; and its j 
fruit is an oblong unilocular capsule, contain- 
ing numerous scobiform seeds. 
The essential character is, nect. a horn or 
spur behind the flower. There are 50 species ] 
of tliis gemiSjWhich exceedingly resembles the i 
oplirys. The most remarkable species are 
the following : 
1. 'l’he maseula, or male fool-stones, has a 
root composed of two bulbs, crowned with 
oblong, broad, spotted leaves ; upright 
stalks, a foot high, with one or two narrow 
amplexicaule leaves, and terminated by a long 
spike of reddish-purple flowers having the 
petals reflexed backward ; a quadrilobed cre- 
nated lip to the nectarium, and an obtuse ; 
horn. The flowers of this species possess a 
very agreeable odour. 
2. The morio, or female orchis, has a few 
amplexicaule leaves ; and terminated by a 
short loose spike of flowers, having counivent 
petals, a quadrified crenated lip to the necta- 
rium, and an obtuse horn. 
3. The militaris, or man-orchis, has erect 
flower- stalks, eight or ten inches high, termi- 
nated by a loose spike of ash-coloured and 
reddish flowers, having confluent petals ; a 
quinquefid, rough, spotted lip to the necta- 
rium, and an obtuse horn. The structure of - 
the flowers exhibits the figure of a naked man ; 
and is often of different colours in the same 
flower, as ash-colour, red, brown, and dark- j 
striped. 
All the orchises are very hardy perennials* ; 
with bulbous fleshy roots. The flowers ap- 
pear in May, June, and July, but principally 
inJur/e: their mode of flowering is univer- 
sally in spikes, many flowers in each spike ; 
and" each flower is composed of five petals in 
two series, and a nectarium. The season for 1 
removing them is in summer, after they, have 
done flowering, when their leaves and stalks 
decay: plant them three inches deep, and, 
lei them remain undisturbed several years ; - 
for the less they are removed the stronger 
they will flower. 
This plant flourishes in various parts of 
Europe and Asia, and grows in our country 
spontaneously, and in great abundance, ft 
is assiduously, cultivated in the East ; and the, 
root of it forms a considerable part of the 
1 1 
