566                                              PYRITES

PYRAMUS AND THISBE                        IJ

King Cheops, known as Suphis or Khufu (B. C. 3733-3700), and is the largest, being 484 feet in height and its side on the base-level measuring 760 feet. It covers over 13 acres or, as commonly compared, is "more than twice the extent of St. Peter's at Rome." The second, which is 707 feet high and measures 454 feet on a base-side, was built by Chepheren (Shafra) (B. C. 3666-3633). Its measurements are exactly half those of Chepheren which seems to have been done intentionally. It now is 354 feet high and has a base-side of 218 feet. Myce-rinos has a coating of red granite from Syene while limestone was employed on the other two, a little of which still remains on the summit of the second.

In each is found the sepulchral chamber where the mummy of the king was placed; then a large slab of stone weighing 50 or 60 tons was cut and fitted into the entrance. So closely do these fit that explorers are Dften forced to break them or bore around. In the great pyramid the king's chamber is located well-up in the heart of the structure. It has five compartments, one large or main one where the mummy rested, and four successive chambers above, one placed above the other and separated by a slab of granite leveled and polished only on the undersurface. This group of rooms is connected with the outside by means of two air-channels and a long passage which leads downward for some distance and then re-ascends at an angle of 26° to the surface, piercing about 47 feet 6 inches from above the foundations. This channel that opens on the surface extends downward, beyond the meeting with the first, into the rock below the pyramid to a chamber called the well. A third chamber is found in the heart of the pyramid, about halfway between the bottom and the king's chamber, and is connected with it. This is known as the queen's chamber. These halls or passages are lined with polished granite and limestone, and show the marvelous ability and knowledge that the Egyptians possessed in supporting so great a superincumbent weight as is above these chambers and passages. In the great pyramid a V-shaped arch discharges the weight from off the kirig's chamber; and the top of the passage leading to it is heightened to about 28 feet for a great length, where the downward force is greatest, and the walls resemble- inverted stairways and in this form come together at the top.

In the second pyramid the chamber is partly above and partly beneath the rock-foundation, while in the Mycerinos it is entirely below. A small chapel was always built near every pyramid, but in nearly every case it has perished.

Other pyramids of importance and of great dimensions are found at various other places in the necropolis. Many of the

smaller pyramids were built by people of royal blood, while the wealthy buried their dead in what are called mastabas and differ from the pyramidal shape, oftentimes being cut into the solid rocks.

Architects and engineers have never solved the puzzle of the pyramids, though many theories have been put forth. Some it seems have come near to the truth in a numerical plan, but the astronomical theory apparently fails. James Ferguson says : "Nothing more perfect, mechanically, has ever been erected since that time."

Consult J. Ferguson: History of Architecture; Perrot and Chipiez : History of Ancient Egyptian Art; and Mathews : The Story of Architecture.

Pyr'amus and This'be, two lovers whose tragical history is told by Ovid in the 4th book of his Metamorphoses. They were natives of Babylon, and tenderly attached; but, as their parents would not consent to their marriage, they had to content themselves with secret interviews by night. On one occasion they arranged to meet at the tomb of Ninus, where Thisbe, who was first at the trysting spot, was startled to discover a lion. She immediately ran away but dropped her robe, which the fierce animal, that had just torn an ox in pieces, covered with blood. Soon after, Pyramus, appeared and, seeing Thisbe's robe, concluded she had been murdered and killed himself. When Thisbe returned soon after, and saw her lover lying dead on the ground, she immediately put an end to her own life.

Pyr'enees, the mountain chain that divides France from Spain. It stretches from the Mediterranean to the southeastern corner of the Bay of Biscay, 270 miles, the breadth varying from 15 to 70 miles. The chain is divisible into three distinct portions — the western, the central and the eastern. Both on north and south the mountains sink down to the plains in a series of terraces with precipitous faces, the general slope on the Spanish side being somewhat steeper than that on the French side. See Taine's Voyage aux Pyrenees.

Pyrenoids {pî-rē'noidz) (in plants). In the chloroplasts of certain algæ, as in Spiro-gyra, there usually are embedded one or more colorless bodies, each one often surrounded by a jacket of starch. These bodies are reserve proteid and are known as pyrenoids.

Pyrites (pï-rï'têz), a name employed by mineralogists to designate a number of minerals which are compounds of metals with sulphur or arsenic or both. They are hard and brittle, have a metallic appearance, and frequently are yellow. The kinds most usually mentioned are iron, copper and arsenical. Iron pyrites is sometimes mistaken for gold, on account of its yellow color, and therefore is called fool's gold. It is much used in the manufacture of sulphuric acid,