468 Primitive Gkekle: Mvcenian Aut. the Tirynthian wall. The citadel gate at Mycena: forms the transition between the two systems. Regularity of masonry is seen at its best in the domed-tombs, particularly the Treasury of Atreus, which testifies to the great care bestowed upon it. The vertical and horizontal faces have been sufficiently well prepared to dispense with binding material ; here and there, however, clay mortar with a small proportion of lime has appar- rently been used to hide imperfect joints, after the blocks were set up.' As a rule, the vertical joints fal! over the centre of the stones immediately below ; it is an arrangement which endows the construction with additional strength. The proportion of Kiu, i8i.— Poriion of iionh-ta^t wall of ciudel. height to length in these units varies from one to three, four, or even five. Although these blocks are somewhat irregular, and their faces only partially dressed, the proportions are practically those of Hellenic masonry seen in the Messenian wall, and very nearly what Vitruvius calls " isodomon." Nevertheless, the masons who carried out the work in question were the pupils of the builders of the Tirynthian fortifications. Take as an instance of this transmission and persistency of methods, one of the rings composing the crown of the domed-tombs : the stones of which they are made up have not their rectilinear sides in the pro- longation of the rays which from the centre would fall on the points of the circumference where two of the units of one ring ' F. Thiersch, Die Thohs des Atreus tu Myfcerue.
