It is now necessary to return to figs. 6 and 7, Plate I., which represent the bolt with the single pin or tumbler, in order to trace the origin and development of Class B. Whilst in Scandinavia and the north of Europe, the key was applied to the upper part of the tumblers, above the bolt, as shown in the preceding examples of the hand-drawn lock; in Egypt, Asia, and probably in parts of Europe also, another system combining rapidity with security was introduced. A key with a single tooth was inserted beneath the bolt, and by raising the tooth vertically and applying it to the lower end of the tumbler, the latter was pressed out of the hole and raised clear of the bolt, and the tooth occupying its place in the hole, the key itself was made to hook back the bolt, so that the whole operation was performed with one hand holding the key. Fig. 9B, Plate II., represents this kind of lock, which may be termed a key-drawn, as distinct from a hand-drawn lock. As with the tumbler locks of the north of Europe so with the southern variety, security was obtained by multiplying the number of tumblers and varying their position. Figs. 10 to 12B, Plate II., are drawings of a wooden pin-lock and key obtained by myself in Egypt, which is of the kind habitually in use there at the present time. It has two tumblers in line. In fig. 10B the lock is represented with the key, A, in it and the tumblers raised, preparatory to drawing the bolt B. Fig. 11B is the key, and in fig. 12B the lock is shown shut, with the tumblers down and the key lowered preparatory to withdrawing it from the lock. Mr. ROMILLY ALLEN, in the paper already referred to, gives an illustration of one precisely similar which he obtained in Persia. Figs. 13B and 14B, Plate III., shows an exactly similar lock in the India Museum, obtained by Sir DOUGLAS FORSYTH at Yarkand, a facsimile of which is in my collection. This kind of lock is also used in Turkey; their identity throughout the region here spoken of is such as to leave no doubt of their having been copied from one another, and indicates the area of their distribution, about which something will be said further on.