OBELISK, (front the Latin, obeliscus) a quadrangular pyramid, very slender and high ; raised as an ornament in some public place, or to show some stone of enormous size ; and frequently charged with inscriptions and hiero glyphic-4.
Borel derives the word from the Greek, ol31,:tog, a spit, broach, spindle, or even a kind of lung javelin. Pliny says, the Egyptians cut their obelisks in form of sunbeams; and that, in the PlBenician language, the word obelisk signi fies rag.
The Egyptian priests called their obelisks the sun's fin gers; because they served as styles, or gnomons, to mark the hours on the ground. The Arabs called them Pharaoh's needles ; the Italians call them ayuylia ; and the Eng lish Cleopatra's needles. See NEEDLES.
The, difference between obelisks and pyramids, according to some. consists in this, that the latter have large bases, and the former very small ones, compared with their height though Cardau makes the difference to consist in this, that obelisks are to be all of a piece, or consist of a single stone; and pyramids of several.
The proportions of the height and thickness are nearly the saute in all obelisks; that is, their height is nine, or nine and a half. sometimes ten times their thickness ; and their thick ness, or diameter, at top, is never less than half, nor greater than three-fourth-, of that at bottom.
This kind of monument appears to have been very ancient; and, we are told, was first made use of to transmit to poste rity the principal precepts of philosophy which were engra ver on them in hieroglyphic characters. In after-times they were used to immortalize the actions of heroes, and the me more of persons beloved.
The first obelisk we know of was that raised by Pouneses, king of Egypt, in the time of the Trojan war. It was 40 cubits high. and. according to Ilerodotus. emliloyed :20,000 men in building. Thins, another king of Egypt, raised one of 45 cubits; and Philadelphus another, of 88 eu bits, in memory of A rsorme. See l'onunvitv.
Augustus erected an obelisk at Rome, in the Campus Mar tius, which served to mark the hours on an horizontal drawn on the pavement.
F. Kircher reckons up fourteen obelisks, celebrated above the rest, viz., that of Alexandria, that of the Barherins, those of Constantinople. of the Mons Esquilinns, of the Campus Flaminins, of Florence, of Heliopolis, of Lndovisio, Or St. Mahut, of the Medici, of the Vatican, of Mount Callus, and that of Pamphylia.
One of the uses of obelisks among the ancients was, to find the meridian altitudes of the sun at different times of the year. Hence they served instead of very large gnomons. One of the obelisks now standing at Rome, that of St. John's Lateran. is in height 108 English feet, with(nit the pedestal ; and the other obelisk, brought to Borne by Augustus, buried under the Campus Martins, wants lint little of the same height. Pliny gives a description of this gnomon, lib. xxxvi. sect. 15. From hint it appears, that there was laid down, from the flot of the obelisk northward, a level pavement of stone, equal in breadth to the breadth of the obelisk itself, and equal in length to its shadow at noon, upon the shortest day ; that is to say, that its length was to the height of the obelisk, almost as 22 to 10, and that under this pavement, there were properly let in parallel rulers of brass, whose distance from the point, directly under the apex of the obelisk, were pet reedy equal to the length of the shadow thereof at noon. on the several days of the year, as the same lengths decreased from the shortest day to the longest, and again increased from the longest day to the shortest. Vide Phil. Trans. No. 482, art. 5, vol. xliv. p. where we also find some remarks by Folkes on lfardonin's Amendment of a Passage in Pliny's _Vatural History. lib. ii. sect. ''4. about the length of the shadows of gnomons in different latitudes.