No. 5, an old English lock, exhibits a great advance in principle, being provided with the double action just described as being wanting in No. 4.
No. 6, modern English (no maker’s name), is a single-acting tumbler-lock.
No. 7, by Mace, is a double-acting tumbler, but without exhibiting any peculiarities of construction.
No. 8 is Somerford’s first patent. It is a double-acting draw tumbler-lock; that is, there is a tumbler which is drawn down instead of being lifted, as in most locks.
No. 9, designated, we know not on what grounds, an Indian lock, has a single-acting tumbler with a pin.
No. 10, patented by Thompson in 1805. In this lock there are two tumblers, one of which is single and the other double-acting.
Next follow a considerable number of locks, which differ one from another too slightly to render any formal description necessary. No. 11, by Daniells, is a single-acting tumbler, differing only in form from those previously used. No. 12 is by Walton. No. 13 is Barron’s first patent, taken out in 1774. No. 14 is by Bickerton. No. 15 is a Dutch lock. No. 16 is by Duce, senior. No. 17, by Sanders, is a lock with four double-acting tumblers. No. 18, patented by Cornthwaite in 1789, is so nearly like Sanders’s, brought before public notice in 1839, as to corroborate what we have said concerning the identity, or at least close resemblance, of inventions widely asunder in point of time. No. 19 is by Richards and Peers.
No. 20 is Somerford’s second patent; a lock which seems to embody the principle of Mr. Tann’s “reliance-wards,” patented many years later. No. 21 is Rowntree’s lock, patented in 1790. No. 22 is the first patent lock of Duce, junior, dated 1823. No. 23 is Parsons’ first patent, of 1832. No. 24 is Bickerton’s second. No. 25, patented by Price in 1774; this, so far as at present appears, was the first lock ever constructed with four double-acting tumblers, bearing a closer resemblance than would generally be supposed to those patented by other persons in more recent years. No. 26 exhibits a somewhat similar coincidence. It was introduced by Aubin in 1830, and is furnished with a revolving curtain for the purpose of closing the key-hole during the revolution of the key. Other inventors have since then adopted the revolving curtain; and in a patent taken out so recently as 1852, this appendage is claimed as part of the patent.
No. 27 is Barron’s second patent, dated 1778; a lock which has perhaps been the model for a larger manufacture of plain simple tumbler-locks than any other. No. 28 is by Bird, 1790. No. 29 is the second patent of Duce, junior. No. 30 is Ruxton’s, 1818. No. 31 is Chubb’s simplified lock, 1834. No. 32 is by Marr. No. 33, by Tann, is the “reliance-ward” lock adverted to above as having been anticipated, in respect to its leading principle, by Somerford’s second patent. No. 34 is by Hunter, 1833. No. 35 is Parsons’ second patent, of the same year. No. 36 is by Lang, 1830. No. 37 is Lawton’s, dated 1815. No. 38, patented by Strutt in 1839, has an arrangement for holding the tumblers, in the event of a pressure being applied to the bolt; an arrangement bearing a considerable resemblance to one recently adopted in Chubb’s bankers’ lock. No. 39 is by Scott, 1815. No. 40, Chubb’s patent of 1818, is the original detector-lock of this maker. Most of the detectors since patented by various persons are little other than variations of Chubb’s original.
No. 41, Parsons’ third patent of 1833, is a changeable lock of peculiar construction. The elevation of the tumblers is regulated by an adjusting-screw passing through the lock to the inside of the door; this screw changes the positive but not the relative positions of the tumblers; so that the same difference in the steps of the key must be retained, the change being made only in the length of the bit: the number of changes for each lock is very limited.