54 COMPARATIVE ARCHITECTURE. back to about b.c. 3000, have been discovered by Dr. Arthur Evans, of which the Minoan Palace at Knossos in Crete is an example. The architectural remains of these periods include town-walls, palaces, and tombs. The walls are of three kinds of masonry: (i) '■'■ Cyclopean,'" i.e., masses of rock roughly quarried and piled on each other, without cramp-irons, but with clay mortar, the interstices between the larger being filled with smaller blocks. Examples at Argos, Tiryns, Mycenae, Knossos in Crete, and Athens. (2) Rectangular, i.e., carefully hewn rectangular blocks arranged in regular courses, but the joints between stones in the same course are not always vertical. Examples at Mycenae in the entrances and towers, and the entrance passage in " tholos " or beehive-tombs. (3) Polygonal, i.e., many sided blocks accurately worked so as to fit together. Examples at Mycenae, wall of Acropolis at Athens, and Cnidus. Thus all three styles occur in structures of " Mycenaean " age, although in out-of-the- way places, as in Caria, they survived for centuries. The first is seemingly the parent of the other two : but the common assump- tion that polygonal is later than rectangular masonry cannot be proved with regard to the Pelasgic period. In addition various characteristic features were used : — Corbels. — Sometimes horizontal courses were employed pro- jecting one beyond the other till the apex was reached, producing either a triangular opening as is found above the doorways of the tholos-tombs (No. 15 a, e), or an apparent arch as at Qiniades in Acarnania, Assos, and the gallery at Tiryns, or a dome-shaped roof as in the Treasury of Atreus at Mycenae (No, 15 A, b). Inclined Blocks. — Sometimes inclined blocks forming triangular headed openings were employed as in the early, perhaps pre- historic, sanctuary on Mount Ocha in Euboea, and the ancient shrine of Apollo on Mount Cynthus (Delos). Arches. — A few examples of Greek arcuated work are extant, viz., a Cyclopean arch at Cnidus, an arch with a key-stone (partially dropped) in Acarnania, and an arched gateway at CEniades. A water-channel or drain at Athens, which crosses the town from east to west, is partly arcuated and partly roofed with advancing corbels. The barrel-vault ("kamara") occurs in sub- terranean funeral chambers in Macedonia, and also in the vaulted passages at the theatre of Sicyon, the tunnel leading to the Stadium at Olympia and other places. The "tholos" or beehive-tombs at Mycenae, Orchomenos, and Amyclae were originally modelled on underground huts for the living (Vitruv. ii., i), the precise shape being found by Prof. Adler in Phrygia. At Mycenae the tholoi are confined to the lower city as opposed to the shaft-graves of the upper city. The largest and best preserved is the so-called " Treasury of Atreus " (No. 1 5). It consists of a long entrance passage or " dromos," 20 feet broad by
