It is not known exactly when this took place, but probably at some time during the 18th century, and possibly earlier. This time, the tumblers instead of being vertical (as was the case during what may be called the early tumbler period) were horizontal, resting on a pivot above the bolt and kept down by a spring. Figs. 128, 129, and 130, Plate X., is a tumbler lock in the possession of Mr. CHUBB, found whilst repairing an old house at Funtley, Hants, said to be 200 years old. If so it must be regarded as the earliest specimen of the second tumbler period. The tumbler moves on a pivot, and is kept down by a spring, the revolving key raises the tumbler by pressing up the curved bar attached to it, which raises the stud of the tumbler out of the notch provided for it on the upper side of the bolt, thereby freeing the bolt, so that by further turning the key it is enabled to shoot the bolt. The tumbler, it will be seen, cannot be raised too high. If the plate of the key is long enough to raise the stud of the tumbler out of the notch, a key with a longer plate will answer the same purpose. To remedy this defect and necessitate the employment of a key of exactly the proper size, Mr. BARRON, about the year 1778, introduced an improvement known by his name, represented in fig. 131, Plate X., in which the bolt is provided with a slit along the middle just wide enough to allow the stud to pass; the slit has notches both above and below, so that if the stud is raised too high by a key with too long a plate it is forced into the upper notch and the bolt continues immovable. He also introduced two tumblers requiring to be raised to different heights in order to coincide with the slit in the bolt by means of different projections on the edge of the key plate, so that the bolt could only be shot by means of a key with a plate expressly constructed to fit the lock, and having two projections of the requisite length. This principle of employing two or more tumblers is the one on which nearly all subsequent improvements have been effected. Those who desire to prosecute the subject further will find a variety of modern tumbler locks in my collection introduced during the latter half of the last and commencement of the present century. They are all, in the main, varieties of one principle, terminating in the CHUBB and HOBBS locks of the present time. As this paper relates only to primitive locks I do propose to describe them here. The continuity which pervades all the ramifications of the modern lock is not less complete than in the earlier forms, and would well bear treating in the same manner as those which I have described. The Bramah lock, though in external appearance differing from the others, is no less based upon the earlier forms, and may be described as a union between the _ward_ and the _tumbler_ systems. It is a ward system, because the obstructions introduced into the mechanism are intended to prevent the turning of the key to shoot the bolt by any