a curious machine for representing the motions or phases of the heavenly bodies. See Astronomy, n. 13, 487, 488, and 490.

The reason of its being called an Orrery, was this: Mr Rowley, a mathematical instrument maker, having got one from Mr George Graham, the original inventor, to be sent abroad with some of his own instruments, he copied it, and made the first for the earl of Orrery. Sir Richard Steel, who knew nothing of Mr Graham's machine, thinking to do justice to the first encourager, as well as to the inventor, of such a curious instrument, called it an Orrery, and gave Mr Rowley the praise due to Mr Graham.

It would be too great an undertaking here to give an account of the mechanism of the larger sort of orrees, which represent the movements of all the heavenly bodies; nor indeed can it be done either by diagram or description, to render it intelligible to the most discerning reader; but, instead of that, we shall exhibit an idea of the theory and structure of an useful, concise, and portable planetarium, which any gentleman may have made for a small expense, and will exhibit very justly the motions of all the primary planets about the sun, by wheel-work; and those that have secundaries, or moons, may have them placed about their primaries moveable by the hand, so that the whole shall be a just representation of the solar system, or true state of the heavens, for any given time of the year.

In order to this, we must compare, and find out the proportion, which the periodical times, or revolutions of the primary planets, bear to that of the earth: which, with respect to the Geocentric Sidus, are not as yet sufficiently ascertained; but those of the other planets are such as are expressed in the table below, where the first column is the time of the earth's period in days and decimal parts; the second, that of the planets; the third and fourth are numbers in the same proportion to each other: as, If we now suppose a spindle or arbor with six wheels fixed upon it in an horizontal position, having the number of teeth in each corresponding to the numbers in the third column, viz. the wheel AM of 83 teeth, BL of 52, CK of 50 (for the earth), DI of 49, EH of 7, and FG of 5; and another set of wheels moving freely about an arbor, having the number of teeth in the fourth column, viz. AN of 20, BO of 32, CP of 50 (for the earth), DQ of 75, ER of 83, and FS of 148; then, if those two arbors of fixed and moveable wheels are made of the size, and fixed at the distance from each other, as here represented in the scheme, the teeth of the former will take those of the latter, and turn them very freely when the machine is in motion.

These arbors, with their wheel, are to be placed in a box, of an adequate size, in a perpendicular position; the arbor of fixed wheels to move in pivots at the top and bottom of the box; and the arbor of moveable wheels to go through the top of the box, to 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 moveable 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, representing its proper planet.

If then on the lower part of the arbor of fixed wheels be placed a pinion of several teeth, a wheel 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 respective periods of time, very exactly. For while the fixed wheel CK moves its equal CP once round, the wheel AM will move AN a little more than four times round, and so will nearly exhibit the motion of Mercury; and the wheel FG will turn the wheel FS about \(\frac{1}{29}\) round, and so will truly represent the motion of Saturn: and the same is to be observed of all the rest.

**ORRERY (Earls of).** See Boyle.

**ORRICE.** See Iris.

**ORRUS,** in botany, a name by which many of the ancients called the cultivated pine-tree, from its being remarkably full of juice.

The first person who has given us the name is Theophrastus; but he is followed in it not only by the other Greeks, but also by the Latins, who have called the same tree for the same reason *sapinus*, a contraction or abbreviation of the word *sapinurus*, the juicy pine. Pliny tells us, that this last was the name of the manured pitch tree; but in this he errs; for Vitruvius, and others, tell us, that the pine-nuts, *nucis pinae*, which were eaten and used in medicine, were the fruit of the *sapinurus*, or *sapinus*; and it is evident, that these must be the produce of a pine-tree, not of a pitch-tree, or any thing of the fir kind.

**ORSATO (Sertorio),** a celebrated antiquarian, historian, and poet, was born at Padua in 1617, and early discovered a taste for literature and the sciences. He applied himself to searching out antiquities and ancient inscriptions; for which purpose he travelled through all the different parts of Italy, and in the mean time poetry was his amusement. When advanced in age, he taught natural philosophy in the university of Padua. He was also a member of the academy of the Ricovrati. Having presented to the doge and senate of Venice the history of Padua, which he had dedicated to them, he made a long speech, during which he struggled with a natural want, and died of suppression of urine, on the 3rd of July 1678. He wrote a great number of books which are esteemed, some in Latin, and others in Italian.

He ought not to be confounded with John Baptist Orsato, an able physician and antiquary, who was born at Padua in 1673, and wrote, 1. *Dissertatio epigraphiae de Lucernis antiquis.* 2. A dissertation De patria antiquorum. 3. A small treatise De flaminis veterum; and some other works.

**ORSI (John Joseph),** an ingenious philologer and poet, was born at Bologna in the year 1652; and studied polite literature, philosophy, the civil law, and mathematics. His house was a kind of academy, where many persons of literature regularly assembled. He wrote many ingenious sonnets, pastorals, and other works in Italian, and died in 1733.

**ORTEGAL CAPE,** the most northern promontory of Spain, where there is also a castle of the same name. W. Long. 8° 20'. N. Lat. 44° 0'.

**ORTELIUS (Abraham),** a celebrated geographer, born at Antwerp, in 1527, was well skilled in the languages and the mathematics, and acquired such reputation by his skill in geography, that he was named the *Ptolemy of his time*. Julius Lipius, and most of the great men of the 16th century, were Ortelius' friends. He resided at Oxford in the reign of Edward VI, and came a second time into England in 1577. His *Theatrum Orbis* was the completest work of the kind that had ever been published, and gained him a reputation equal to his immense labour in compiling it. He also wrote several other excellent geographical works; the principal of which are his *Theatrum*, and his *Synonyma Geographica*. The world is likewise obliged to him for the *Britannia*, which he persuaded Camden to undertake. He died at Antwerp in 1598.

**ORTHEZ,** a city in the province of Bearn, and perhaps the meanest in all France. It was, however, till the Revolution, a bishop's see. The cathedral is a wretched edifice, very ancient, built in a barbarous style, and almost in ruins. The remains of the walls of Orthez are very noble, and its situation is fine, on a hill, which commands the town and a great extent of country. The people call it *Le Chateau de la Feine Jeanne*, because that queen resided in it during many years, in preference to the castle of Pau. Some of the apartments, though in ruins, may yet be entered. The princess Blanche, daughter to John king of Arragon and Navarre, was shut up, and died here, in 1464. Her brother being dead, she became heiress to the crown of Navarre; but her father having delivered her into the hands of her younger sister Leonora countess