Primitive Greece: Mycenian Art. The oldest buildings that have been uncovered are the prehistoric houses at Thera, whose window- frames and ground- sills were wooden ; ' as regards the doors, we can only say that they are represented by gaps in the wall. We are led, therefore, to suppose that the entrance lo these habitations was of the most elementary kind, such as is found in the primitive hut, a mere triangular isocele, whose small side was the sill, and the sloping beams which met the transverse timbers or lintel at the top its main sides (Fig. 189). No simpler arrangement than this opening could well be imagined. When the door was of considerable height, the need of a joist laid across the entry. at about two-thirds of its total height, must have been felt ; be it to maintain the sloping jambs in their right position, and enable them to resist the lateral thrust of the irregular masonry, or to provide the door with a means of closing by a curtain which could be fastened thereto, leaving the space above it uncovered to let in the light. We find some such contrivance in the ancient houses of every epoch (Fig. 190). When windows placed in the proximity of the doorway rendered such an impost superfluous, it disappeared, huge sloping timbers were set up, and gave the door a trapezoidal shape (Fig. 191). It is this door which Schliemann exhumed at Troy, with the carbonized remains of its wooden door-case (Fig. 45).* If, owing to the poor state ' FouQUf, Santorin. ' History of Art.