in astronomy, is an apparent irregularity in the motions of far distant bodies; to call ed, because it is not really in the moving bodies, but arising from the situation of the observer's eye. For if the eye were in the centre, it would always see the motions as they really are.
Optic Pyramid, in perspective, is a pyramid formed by the visible object which is the base, and the rays drawn from the perimeter of that object, which meet at the eye in a point, which is the apex of the pyramid. Hence, also, we may know what is meant by an optic triangle.
Optic Rays, particularly means those by which an optic pyramid, or optic triangle, is terminated.
ORAN, a considerable city, occupied by the Spaniards, in the province of Maestras, in the country of Algiers. It has strong and regular fortifications, and can easily be supplied from Spain with provisions and warlike stores. It lies in 35° longitude west from Greenwich, and in 35° 55' north latitude. Since the year 1732, the Spaniards have held uninterrupted possession of Oran. It has a parish-church, three monasteries, an hospital; and the number of the inhabitants, according to the account given of it by the Spaniards, amount to 12,000. Towards the sea, the city rises in the form of an amphitheatre, and is surrounded with forts and batteries. Close to the city lies a strong castle, Alcazara, in which the Spanish governor resides. On the highest hill stands Fort St Croix, whose guns command the city and the adjacent country. From this fort they make signals of the approach of ships, and carefully watch the motions of the Moors, who often attempt predatory incursions into the neighbouring districts. A considerable number of Mahomedans take refuge in Oran; they dwell in a distinct part of the city, receive pay from the court of Spain, and render loyal services against the Moors. The greatest part of the inhabitants of Oran consists of such as have been banished from Spain; and the same may, in a great measure, be said of the soldiers who compose the garrison. Five regiments are commonly stationed here; but, owing to continual defection, their strength scarcely equals that of four complete regiments. One of them wholly consists of malefactors, who have been condemned to remain here for life; the rest are such as have been transported for one or more years. There is here likewise a military school. Around the city are pleasant gardens; but it is very dangerous to cultivate them, on account of the Moors and Arabs, who frequently lie in ambush among them. The same reason prevents the cultivation of the fields in the vicinity; and the garri- principles we are pledged—and in support of them we are ready to spend the last drop of our blood.—(Signed) Thomas Verner, Grand Master; John Clau, Beresford, Grand Secretary; William James, J. De Joncourt, Edward Ball."
ORCHARD. As an appendix to this article in the Encyclopædia, some of our readers will be pleased with the following means, employed by the Rev. Mr Germerhausen, for promoting the growth of young trees, and increasing the size and flavour of the fruit in orchards.
Having planted several young plum trees in an orchard, he covered the ground, for some years, around the trunks, as far as the roots extended, with flax-shows (a); by which means these trees, though in a grass-field, increased in a wonderful manner, and far excelled others planted in cultivated ground. As far as the shows reached, the grass and weeds were choked; and the soil under them was so tender and soft, that no better mould could have been wished for by a florist.
When he observed this, he covered the ground with the same substance, as far as the roots extended, around an old plum-tree, which appeared to be in a languishing state, and which stood in a grass-field. The consequences were, that it acquired a strong new bark; produced larger and better-tasted fruit; and that those young shoots, which before grew up around the stem, and which it was every year necessary to destroy, were prevented from sprouting forth, as the covering of flax-shows impeded the free access of air at the bottom of the trunk.
In the year 1793, he transplanted, from seed-beds, into the nursery, several fruit-trees; the ground around some of which he covered, as above, with flax-shows. Notwithstanding the great heat of the summer, none of those trees where the earth was covered with shows died or decayed; because the shows prevented the earth under them from being dried by the sun. Of those trees, around which the ground was not covered as before mentioned, the fourth part miscarried; and those that continued alive were far weaker than the former.
The leaves which fall from trees in autumn may also be employed for covering the ground in like manner; but stones, or logs of wood, must be laid on them, to prevent their being dispersed by the wind. In grass-fields, a small trench may be made around the roots of the tree, when planted, in order to receive the leaves. If flax shows are used, this is not necessary; they lie on the surface of the ground so fast as to resist the force of the most violent storm. The leaves which our author found most effectual in promoting the growth and fertility of fruit trees, are those of the walnut-tree. Whether it is, that, on account of their containing a greater abundance of saline particles, they communicate manure to the ground, which thereby becomes tender under them; or that they attract nitrous particles from the atmosphere; or that, by both these means, they tend to nourish the tree both above and below.
Those who are desirous of raising tender exotic trees from the seed, in order to accustom them to our climate, may, when they transplant them, employ flax-shows with
(a) Shows are the refuse of flax when it is scutched or heckled. with great advantage. This covering will prevent the frost from making its way to the roots; and rats and mice, on account of the sharp prickly points of the flax-shows, will not be able to shelter themselves under them.
**ORCHILLA**, a weed used in dyeing, which grows in the Canary islands, and is monopolized by the government. "It is a minute vegetable (says Sir George Staunton), of the lichen kind, growing chiefly upon rocks of a loofe texture, and produces a beautiful violet blue colour."
**ORDEAL.** See this article in the *Encyclopedia*, at the end of which we have given, from Dr Henry's History of England, some strong reasons for suspecting that the ordeal, by fire at least, was a gross imposition on the credulity of an ignorant and superstitious age. This suspicion of imposture is raised to certainty by Professor Beckmann, who, in his History of Inventions, gives us the whole process by which the clergy conducted the trial, and brought proofs of innocence or guilt at their pleasure. The person accused was put entirely under their management for three days before the trial, and for as many after it. They covered his hands (when he was to lift red-hot iron) both before and after the proof; sealed and unsealed the covering. The former was done, as they pretended, to prevent the hands from being prepared any how by art; the latter, that it might be accurately known whether or not they were burnt.
Some artificial preparation was therefore known, else no precautions would have been necessary. It is highly probable, that during the three first days the preventative was applied to those persons whom they wished to appear innocent; and that the three days after the trial were requisite to let the hands resume their natural state. The sealed sealing secured them from the examination of presumptuous unbelievers; for to determine whether the hands were burnt, the three last days were certainly not wanted. When the ordeal was abolished, and this art rendered useless, the clergy no longer kept it a secret. In the 13th century, an account of it was published by Albertus Magnus, a Dominican monk (a). If his receipt be genuine, it seems to have consisted rather in covering the hands with a kind of paste than in hardening them. The sap of the *althea* (marshmallow), the flaky seeds of the flea-bane, which is still used for stiffening by hat-makers and silk-weavers, together with the white of an egg, were employed to make the paste adhere. And by these means the hands were as safe as if they had been secured by gloves.
**ORFFYREUS'S WHEEL**, in mechanics, is a machine so called from its inventor, which he asserted to be a perpetual motion. This machine, according to the account given of it by Gravelande, in his *Oeuvres Philosophiques*, published by Allemaad, Amst. 1774, consisted externally of a large circular wheel, or rather drum, 12 feet in diameter, and 14 inches deep; being very light, as it was formed of an assemblage of deals, Orffyreus having the intervals between them covered with waxed cloth, to conceal the interior parts of it. The two extremities of an iron axis, on which it turned, refted on two supports. On giving a slight impulse to the wheel, in either direction, its motion was gradually accelerated; so that, after two or three revolutions, it acquired to great a velocity as to make 25 or 26 turns in a minute. This rapid motion it actually preserved during the space of two months, in a chamber of the Landgrave of Hesse, the door of which was kept locked, and sealed with the Landgrave's own seal. At the end of that time it was flopped, to prevent the wear of the materials. The Professor, who had been an eye witness to these circumstances, examined all the external parts of it, and was convinced that there could not be any communication between it and any neighbouring room. Orffyreus, however, was so incensed, or pretended to be so, that he broke the machine in pieces; and wrote on the wall, that it was the impertinent curiosity of Professor Gravelande which made him take this step. The Prince of Hesse, who had seen the interior parts of this wheel, but sworn to secrecy, being asked by Gravelande, whether, after it had been in motion for some time, there was any change observable in it, and whether it contained any pieces that indicated fraud or deception? answered both questions in the negative, and declared, that the machine was of a very simple construction.
**ORICOU**, a new species of the vulture, discovered by Vaillant at Orange river in South Africa. As he thinks it unquestionably the most beautiful of its genus, and tells, as usual with him, a wonderful story about it, we have given a figure of this vulture in Plate XLII. Our traveller says, that it is more than three feet high, and eight or nine in breadth of wing. Its feathers, the general hue of which is a light brown, are of a particular kind on the breast, belly, and sides, where they are of unequal lengths, pointed, curved like the blade of a sabre, and bristle up distinct from each other. The feathers being thus separated, would disclose to view the skin on the breast, if it were not completely covered with a very thick and beautiful white down, which is easily seen between the ruffled plumage.
A celebrated naturalist has said, that "no bird has eye-lashes or eye-brows, or, at least, hair round the eyes like that in quadrupeds." This assertion, advanced as a general law of Nature, is a mistake. Not only the oricon has this peculiarity, but we know of many other species in which it exists; such as, in general, all the calaos, the secretary, and several other birds of prey. Before these eye lashes, the vulture in question has stiff black hairs on its throat. All the head and part of the neck are bare of feathers; and the naked skin, which is of a reddish colour, is dashed in certain places with blue, violet, and white. The ear, in its external circumference, is bounded by a prominent skin, which forms a sort.
---
(a) In his work *De Mirabilibus Mundi*, at the end of his book *De Secretis Mulierum*, Amstelod. 1702. 12mo, p. 100. Experimentum mirabile quod facit hominem ire in ignem sine lesionem, vel portare ignem vel ferrum ignitum sine lesionem in manu. Recipe succum bifimalis, et albumen ovi, et femen pyllii et calcem, et pulveriza, et conficce cum illo albumine ovi succum raphant; commiscite; ex hac confectione illaeas corpus tum vel manum, et dimitte siccarit, et potest iterum illaeas, et post hoc poteris audacter sustinere ignem sine nocimento. fort of rounded conch, that must necessarily heighten the faculty of hearing in this species. This kind of conch is prolonged for some inches, and descends down the neck; which induced our author to give it the name of oricon.
Its strength, he says, must be very considerable, if we may judge from its muscles and finesse; and he is persuaded, that there is not a stronger among the whole order of carnivorous birds, not excepting the famous condor, which so many travellers have seen, but of which their descriptions are so different as to render its existence extremely doubtful. But there was no occasion for this reasoning, and those inferences, if what he relates as facts deserve any credit. The oricon which he describes, he first perceived perched on the carcase of a hippopotamus, eagerly devouring its flesh. He shot at it, and wounded it slightly; upon which, "though it had already gorged itself with a considerable quantity of flesh (for upon opening it, he found in its stomach no less a quantity than five pounds and a half), yet its hunger and voracity were such, that it struck its beak into the carcase when attempting to take wing, as if desirous of carrying the whole of it away.
"On the other hand, the weight of the flesh it had devoured rendering it the more heavy, it could not easily rise; so that we had time (says he) to reach it before it was on the wing, and we endeavoured to knock it on the head with the butt-ends of our muskets. It defended itself a long time with great intrepidity. It bit or struck at our weapons with its beak, and its strength was still so great, that every stroke made a mark on the barrel of the piece."
ORIENT, the east, or the eastern point of the horizon.
ORIENT Equinoctial, is used for that point of the horizon where the sun rises when he is in the equinoctial, or when he enters the signs Aries and Libra.
ORIENT Aestival, is the point where the sun rises in the middle of summer, when the days are longest.
ORIENT Hysterical, is the point where the sun rises in the middle of winter, when the days are shortest.
OROTAVA, a town in the island of Teneriffe, at the bottom of those mountains out of which the Peak rises, neatly built of stone, on an irregular surface. The most remarkable object near it is a dragon's blood tree, of which the trunk measures, at the height of ten feet from the ground, 36 feet in girth. Concerning this tree there is a tradition current in the island, that it existed, of no inconsiderable dimensions, when the Spaniards made the conquest of Teneriffe, about three centuries ago; and that it was then, what it still is, a landmark, to distinguish the boundaries of landed possessions near it.
Distant about three miles on the sea coast is the porto, or seaport, of Orotava, where is carried on a considerable degree of commerce, principally for the exportation of wine. It is chiefly, as at Madeira, in the hands of a few British commercial houses, which import, in return, the manufactures of Great Britain. Within a mile is a collection of living plants from Mexico, and other parts of the Spanish dominions in America. From hence they are to be transplanted into Spain. It is an establishment of some expense; and, whatever may be its success, it shows a laudable attention, on the part of that government, to the promotion of natural knowledge.
OROTCHYS and BITCHYS, two tribes of Tartars, who were visited by La Perouse in 1787, and of whose manners he gives such an account as renders it difficult to say whether they have the best claim to be called a savage or a civilized people. He fell in with a small village of them on the east coast of Tartary, in a bay to which he gave the name of Baie de Gaffrie, in Lat. 51° 29' North, and Lon. 130° 39' East from Paris.
Their village, their employment, their dress, and their apparent ignorance of all religion, bespoke them savages. Their village was composed of four cabins, built in a solid manner, of the trunks of fir-trees, and covered with bark. A wooden bench compassed the apartment round about; and the hearth was placed in the middle, under an opening large enough to give vent to the smoke.
This village was built upon a tongue of low marshy land, which appeared to be uninhabitable during the winter; but on the opposite side of the gulf, on a more elevated situation, and exposed to the south, there was, at the entrance of a wood, another village, consisting of eight cabins, much larger and better built than the first. Above this, and at a very small distance, were three yurts, or subterraneous houses, perfectly similar to those of the Kamtchadals, described in the third volume of Captain Cook's last voyage; they were extensive enough to contain the inhabitants of the eight cabins during the rigour of the cold season; besides, on some of the skirts of this village were seen several tombs, which were larger and better built than the houses; each of them enclosed three, four, or five tiers, of a neat workmanship, ornamented with Chinese stuffs, some pieces of which were brocade. Bows, arrows, lines, and, in general, the most valuable articles of these people, were suspended in the interior of these monuments, the wooden door of which was closed by a bar, supported at its extremities by two props.
Their sole employment seemed to be the killing and curing of salmon, of which they eat raw, the innut, the gills, the small bones, and sometimes the entire skin, which they strip off with infinite dexterity. When the stript salmon were carried to the huts, the women, in the most disgusting manner, devoured the mucilaginous part of them, and seemed to think it the most exquisite food. Every cabin was surrounded with a drying place for salmon, which remain upon poles, exposed to the heat of the sun, after having been during three or four days smoked round the fire, which is in the middle of their cabin; the women, who are charged with this operation, take care, as soon as the smoke has penetrated them, to carry them into the open air, where they acquire the hardness of wood.
The bones of the salmon so cured were scattered, and the blood spread round the hearth; greedy dogs, though gentle and familiar enough, licked and devoured the remainder. The nativeness and stench of this people are disgusting. There is not perhaps anywhere a race of people more feebly constituted, or whose features are more different from those forms to which we attach the idea of beauty; their middle stature is below four feet ten inches, their bodies are lank, their voices thin and feeble, like that of children; they have high cheeks. Orochys, cheek bones, small clear eyes, placed diagonally; a large mouth, flat nose, short chin, almost beardless, and an olive-colored skin, varnished with oil and smoke. They suffer their hair to grow, and tie it up nearly the same as we do; that of the women falls loose about their shoulders, and the portrait which has just been drawn agrees equally well with their countenances as those of the men, from whom it would be difficult to distinguish them, were it not for a slight difference in the dress, and a bare neck; they are not, however, subjected to any labour, which might, like the American Indians, change the elegance of their features, if nature had furnished them with this advantage. Their whole cares are limited to the cutting and sewing their clothes, disposing of their fish to be dried, and taking care of their children, to whom they give the breast till they are three or four years of age.
With respect to dress, the men and little boys are clothed with a waistcoat of nankeen, or the skin of a dog or a fish, cut in the shape of a waggoner's frock. If it reach below the knee, they wear no drawers; if it do not, they wear none in the Chinese style, which fall as low as the calf of the leg. All of them have boots of seal's skin, but they keep them for the winter; and they at all times, and of every age, even at the breast, wear a leather girdle, to which are attached a knife in a sheath, a flint to strike a light with, a pipe, and a small bag to contain tobacco. The dress of the women is somewhat different; they are wrapped up in a large nankeen robe, or salmon's skin, which they have the art of perfectly tanning, and rendering extremely supple. This dress reaches as low as the ankle bone, and is sometimes bordered with a fringe of small copper ornaments, which make a noise similar to that of small bells. Those salmon, the skins of which serve for clothing, are never caught in summer, and weigh thirty or forty pounds.
Though they had neither priests nor temples, they seemed to be believers in foretelling, and took the motion of the Frenchmen's hands, when writing, for figs of magic. Thus far they appeared savages.
Their sacred regard of property, their attention to their women, and the delicacy of their politeness to strangers, would, on the other hand, do honour to the most civilized nation. While Peroufe and his people were in the bay, one of the families took its departure on a voyage of some length, and did not return during their stay. When he went away, the matter of the family put some planks before the door of his house, to prevent the dogs from entering it, and in this state left it full of their effects. "We were soon (says our author) so perfectly convinced of the inviolable fidelity of these people, and their almost religious respect for property, that we left our packs full of stuffs, beads, iron tools, and, in general, every thing we used as articles of barter, in the middle of their cabin, and under no other seal of security than their own probity, without a single instance of their abusing our extreme confidence; and on our departure from this bay, we firmly entertained the opinion, that they did not even suspect the existence of such a crime as theft."
Their attention to their women, so uncommon among savages, was displayed in their exempting them from hard labour; in their never concluding a bargain with the Frenchmen without previously consulting their wives; and in their reverting the pendent silver ear-rings and copper trinkets, which they purchased, for their wives and daughters. Of the delicacy of their manners to strangers, we shall give the following interesting instance in the words of Peroufe's translator:
Observing with what repugnance they received presents, and how often they refused them with obstinacy, "I imagined (says Peroufe) I could perceive, that they were perhaps delirious of more delicacy in the manner of offering them; and to try if this suspicion were well founded, I sat down in one of their hovels, and after having drawn towards me two little children, of three or four years old, and made them some trifling caresses, I gave them a piece of rose-colored nankeen, which I had brought in my pocket. The most lively satisfaction was visibly testified in the countenances of the whole family, and I am certain they would have refused this present, had it been directly offered to themselves. The husband went out of his cabin, and soon afterwards returning with his most beautiful dog, he entreated me to accept of it. I refused it, at the same time endeavouring to make him understand, that it was more useful to him than to me; but he insisted; and perceiving that it was without success, he caused the two children, who had received the nankeen, to approach, and placing their little hands on the back of the dog, he gave me to understand, that I ought not to refuse his children.
"The delicacy of such manners cannot exist but among a very polished people. It seems to me, that the civilization of a nation, which has neither flocks nor husbandry, cannot go beyond it. It is necessary to observe, that dogs are their most valuable property; they yoke them to small and very light sledges, extremely well made, and exactly similar to those of the Kamtschadals. These dogs, of the species of wolf dogs, and very strong, though of a middle size, are extremely docile, and very gentle, and seem to have imbibed the character of their masters."
ORTHODROMICS, in navigation, is great-circle sailing, or the art of sailing in the arch of a great circle, which is the shortest course: For the arch of a great circle is orthodromia, or the shortest distance between two points or places.
ORYCTEROPUS, the name given by M. Geoffroy, professor of zoology in the French museum of natural history, to the animal called by other zoologists Myrmecophaga Capensis. (See Myrmecophaga, Encycl.) He considers it as a distinct genus, and seems indeed to have proved, by a comparison of the organs of the orycteropus with those of the tatoua desjardins of Linnaeus, and of the myrmecophagi, that this genus is intermediate, by its forms and habits, between those two families. It approaches to the tatoua in its organs of mastication, and the form of the toes and nails, and in having a short and single caecum, whilst that of the myrmecophagi is double, as in birds, by the reuniting of the bones of the os pubis, which are not articulated together in the myrmecophagi. The orycteropus, however, bears a relation to the latif, since it has, like them, a very small mouth, whence its tongue, covered with hair, may be protruded to a considerable length. Finally, the habits of the orycteropus resemble those of the animals to which it approaches the most; it does not climb trees, but lives under the earth like the tatoua; Orycteropus. Molar teeth (six) with flat vertices; the body covered with hair.
The orycteropus, as appears from the preceding, connects the tatus with the myrmecophagi and with the pangolin manis of Linnaeus. The large fossile species found in Paraguay, for which Citizen Cuvier has established a new genus, under the name of megaterium, is intermediate between the sloth and the myrmecophagous; and, lastly, the astonishing animal of New Holland, covered with bristles like the porcupine, supported by very short legs, and of veryingular conformation, and with a head round at the occiput, terminating in a stout, without teeth, very slender, long, and cylindrical, and described by Mr George Shaw under the name of myrmecophaga aculeata, appears to have very striking relations to the pangolin and the orycteropus; from hence it follows, that in consequence of these important acquisitions, we ought for the future to count, in the number of our natural orders, that of the edentated, or edentate, consisting of the following genera: Dasypus, orycteropus myrmecophaga, and aculeata, manis, myrmecophaga, megaterium et bradyurus.