=Locks and Keys.=--The earliest and simplest form of door fastening used by the Greeks seems to have consisted of a bar of wood set behind the door, and made to slide into a hole or staple in the sidepost. An advance on this arrangement was soon made, when the bar was pulled to by a strap from the outside, and could be opened again from the outside by means of a key passed through a hole in the door, and adapted to lift up the pegs which held the bar fast in position. This is the type of lock mentioned in the _Odyssey_,[47] where Penelope releases the strap from the hook to which it was fastened, puts in the key, and lifts the pegs, "striking them fairly." The key for such a lock will probably have resembled No. =440=, marked _a_ in fig. 186 below, the working of which is shown in the sketch (fig. 184).[48] It was passed narrow-wise through the central slot, then turned, and drawn back so as to lift up the pegs fitted in grooves in the side slots. The bar below would thus be freed and could be drawn to and fro by the strap. This type of lock is still sometimes used in the East.[49] [Illustration: FIG. 184.--HOMERIC LOCK (RESTORED).] [Illustration: FIG. 185.--ROMAN LOCK, WITH RESTORATIONS SHOWING ORIGINAL MECHANISM AND USE OF KEY (NO. 441). 3:7.] [Illustration: FIG. 186.--ROMAN KEYS. 2:3.] The majority of Roman locks, though of a more complicated structure, are made on the same principle, as may be seen from the ancient lock No. =441= (probably from Pompeii) here exhibited, together with model lock of the same type (No. =442=) and a diagram showing its original arrangement (fig. 185_a-d_). Here the bolt has been shot through the end link of a chain, part of which remains (fig. 185_c_). It is secured by pins, the ends of which fit into a series of perforations in the bolt and are kept down by a spring. The bolt was released by a key fitted with teeth corresponding to the perforations (fig. 185_d_). The key lifted the pins out of the holes and took their place. The bolt was then drawn aside, as the key was moved along the horizontal slot. On account of the double movement, first vertical and then horizontal, the keyhole is in the shape |¯. Several bolts, keys (_e.g._ No. =442=; fig. 186_c_), and door plates for locks of this type are exhibited in this Case. Three keys from Syria are shown (No. =443=) fitted into the wards of the actual bolts for which they were made. Notice the projections on the ring of key _c_, which were used for shooting a supplementary bolt, a common device in Roman locks.