[19] Mr. BONOMI gives an illustration of the way in which the modern Egyptian keys are carried by merchants at Cairo on the shoulder at the present time; these keys however are straight, and are hung to a stick over the shoulder, and are not sickle-shaped as described by EUSTATHIUS. We must now return to fig. 2, Plate I., in order to trace the third class, C, of locks and padlocks fastening with a spring catch. It seems probable that fixed locks may have preceded hanging ones, although, on the other hand, the want of some contrivance for securing property must have been felt in connection with saddle-bags, panniers, and other appliances of nomadic life, and in a condition of society which preceded the use of fixed abodes. Be this as it may, it seems possible to trace the employment of spring locks by means of survivals from the common door-bolt. The origin of the spring padlock, in the present state of my knowledge on the subject, is doubtful. The sequence which I here assume is only tentative, and it is probable that connecting links with more primitive contrivances may be supplied hereafter. The defect of the common bolt, as I have already shown, was its insecurity as an outside fastening; in fact it afforded no security at all, and to remedy this defect and make it inaccessible, except by means of a key, several different contrivances appear from the first to have suggested themselves; amongst others, one of the simplest was adopted in connection with the Scandinavian bolt, a specimen of which, probably a modern survival of an ancient form, was exhibited in the Scandinavian Section of the Exhibition of 1867, and is figured in M. LIGER'S work.[20] We must suppose the handle in fig. 2, Plate I., and its neck connecting it with the bolt, to be removed, leaving only the slit in the door along which the neck of the handle slid, and that a similar slit was made in the bolt also. The key, which was of iron, was T-shaped; it was inserted from the outside through the slit in the door, and in the bolt, with the arms of the T in a horizontal plane; it then received a quarter turn so that the arms of the T were brought into a vertical plane, and it was then pulled back, when the returns of the T were made to fit into two holes provided for them on either side of the slit in the bolt, on the inside, figs. 1C and 2C, Plate IV. By this means the key obtained a grip of the bolt, and it was only necessary to press it to one side in order to shoot it. This bolt, which is taken from M. LIGER'S work, so closely resembles the next one to be described, that if he had been a less careful writer one might suppose that it was the same lock, and that he had omitted to represent the spring which alone constitutes the improvement shown in figs. 3C, 4C, and 5C, Plate IV., which was presented to me by Dr. ENGELHARDT, at Copenhagen. It is still in use on barn and outhouse