Whilst in some of the more modern contrivances the external form of the Roman spring padlock was retained, the interior mechanism having undergone changes, in others the interior mechanism is retained, the external form having adapted itself to the more modern uses. Figs. 39C, 40C, and 41C, Plate VI., is an old padlock which I obtained in Paris, the date of which I have been unable to determine, but a precisely similar one is attached to the iron chest of the Royal Society, which was presented to the Society in the year 1665, and for the knowledge of which I am indebted to Dr. JOHN EVANS, F.R.S., the Treasurer of the Society. Externally it resembles the modern padlock, but both ends of the semicircular staple are provided with springs on the principle of the Roman padlock. It is opened by means of a revolving key of modern form, which is inserted into the side of the padlock, and which, when given a quarter turn presses back the three springs upon the bolts, and the staple is then withdrawn bodily from the body of the lock. In this case, the staple, being quite separate from the lock, would be liable to be lost, as with the spring of the Roman padlock; so to remedy this defect we see in figs. 42C and 43C, Plate VI., obtained at Clermont-Ferrand, in Auvergne, an improvement in which one of the arms of the staple passes down through the padlock and out at the bottom of it, where it terminates in a button, intended to prevent its being drawn entirely out and separated from the lock. The other arm is furnished with a spring as in the last example and, like it, is opened by a revolving key. When the spring is pressed back it is drawn out and merely turned upon its longer arm as a pivot.