a place upon which sacrifices were anciently offered to some deity. The heathens at first made their altars only of turf; afterwards they were made of stone, of marble, of wood, and even of horn, as that of Apollo in Delos. Altars differed in figure as well as in materials: some were round, others square, and others triangular. All of them were turned towards the east, and stood lower than the statues of the gods; and they were generally adorned with sculpture, representing either the gods to whom they were erected, or their symbols. The height of altars also differed according to the different gods to whom they sacrificed. According to Servius, those altars set apart for the honour of the celestial gods, and gods of the higher class, were placed on some pretty tall pile of building, and for that reason were called altariora, from the words alta and ara, a high elevated altar. Those appointed for the terrestrial gods were laid on the surface of the earth, and called area. And, on the contrary, they dug into the earth and opened a pit for those of the infernal gods, which they called Boleae, Nazo, sorbichuli. But this distinction is not everywhere observed: the best authors frequently use ara as a general word, under which are included the altars of the celestial and infernal, as well as those of the terrestrial gods. The Greeks also distinguished two sorts of altars: that whereon they sacrificed to the gods was called θυσιας, and was a real altar, different from the other whereon they sacrificed to the heroes, which was smaller, and called εργαζα. Pollux makes this distinction of altars in his Onomasticon: he adds, however, that some poets used the word εργαζα for the altar whereon sacrifice was offered to the gods. The Septuagint version does sometimes also use the word εργαζα for a sort of little low altar, which may be expressed in Latin by eraticula, being a hearth rather than an altar.

Before temples were in use, altars were erected sometimes in groves, sometimes in the highways, and sometimes on the tops of mountains; and it was a custom to engrave upon them the name, ensign, or character of the deity to whom they were consecrated.

In the great temples of ancient Rome there were generally three altars: the first was placed in the sanctuary, at the foot of the statue of the divinity, upon which incense was burnt and libations offered; the second was before the gate of the temple, and upon it they sacrificed the victims; and the third was a portable altar, upon which were placed the offering and the sacred vessels. Besides these uses of altars, the ancients swore upon them, and swore by them, in making alliances, confirming treaties of peace, and on other solemn occasions. Altars also served as places of refuge for all those who fled to them.

Altars are doubtless as ancient as sacrifices themselves; consequently their origin is not much later than that of the world. (Gen. chap. iv.) Some attribute their origin to the Egyptians, others to the Jews, others to the patriarchs before the flood. Some carry them as far back as Adam, whose altar is much spoken of by Jewish, and even Christian writers; others are contented to make the patriarch Enoch the first who consecrated a public altar. Be this as it may, the earliest altars of which we find any express testimony are those erected by Abraham.

Altars, in the patriarchal times, were very rude. The altar which Jacob set up at Bethel was nothing but a stone, which served him instead of a bolster; that of Gideon, a stone before his house: and the first which God commanded Moses to erect was probably of earth or unpolished stones, without any iron; for if any use was made of that metal, the altar was declared impure.

The principal altars of the Jews were, the altar of incense, that of burnt-offering, and the altar or table for the show-bread.

The altar of incense was a small table of shittim wood, covered with plates of gold, of one cubit in length, another in width, and two in height. At the four corners were four kinds of horns, and all round a little border or crown over it. This was the altar hidden by Jeremiah before the captivity; and upon it the officiating priest every morning and evening offered incense of a particular composition.

The altar of burnt-offerings was made of shittim wood, and carried upon the shoulders of the priests by means of staves of the same wood overlaid with brass. In the time of Moses this altar was five cubits square and three high; but in Solomon's temple it was much larger, being twenty cubits square and ten in height. It was covered with brass; and at each corner was a horn or spire, wrought out of the same wood with the altar, to which the sacrifices were tied. Within the hollow was a grate of brass, in which the fire was placed; through it fell the ashes, which were received in a pan below. At the four corners of the grate were four rings and four chains, which kept it up at the horns. This altar was placed in the open air, that the smoke of the burnt-offerings might not sully the inside of the tabernacle.

The altar or table for the show-bread was likewise of shittim wood, covered with plates of gold, having a little border round it adorned with sculpture. It was two cubits long, one wide, and one and a half in height. Upon this table, which stood in the holy of holies, were put, every Sabbath day, twelve loaves, with salt and incense.

After the return of the Jews from the captivity, and the building of the second temple, their altars were in some respects different from those described above. That of burnt-offerings was a large pile, built of unhewn stone, 32 cubits square at the bottom, and 24 square at the top. The ascent was by a gentle rising, 32 cubits in length and 16 in breadth.

Altar is also used among Christians for the communion-table. In the primitive church the altars were only of wood, it being frequently necessary to remove them from place to place; but the council of Paris in 509 decreed that no altar should be built but of stone. At first there was but one altar in each church, but the number soon increased; and from the writings of Gregory the Great, who lived in the sixth century, we learn that there were sometimes in the same church twelve or thirteen. In the cathedral of Magdeburg there are no less than 49 altars.

The altar is sometimes sustained on a single column, as in the subterranean chapels of St Cecilia at Rome, &c.; and sometimes on four columns, as the altar of St Sebastian of Crypta Arenaria; but the customary form is, a massive frame of stone-work sustaining the altar table. These altars bear a resemblance to tombs: consequently we read in ecclesiastical history that the primitive Christians chiefly held their meetings at the tombs of the martyrs, and celebrated the mysteries of religion upon them; for which reason it is a standing rule to this day in the church of Rome, never to build an altar without inclosing the relics of some saint in it.