These drawings show a typical example of a full-plate* English lever movement of the middle nineteenth century. This pattern seems to have been first applied to domestic watches in the early 1790s by Peter Litherland, inventor of the rack-lever escapement, and it remained in use with only minor changes until after 1900.

Inevitably one finds variations in detail. The most important, perhaps, is the ‘Liverpool runner’ layout, in which the sequence of lever, escape-wheel, fourth wheel and third wheel is the opposite of that shown here, so that the lever is farthest from the barrel instead of being nearest to it. Furthermore, the balance-spring is sometimes mounted on top of the balance itself, not below it as shown, and this implies some other modifications: the stud for the spring is not directly on the back plate but is at the inner end of a steel bracket which extends over the wheel, and the regulator pointer is mounted on the cock rather than on the back plate. The set-up assembly may be located on the barrel bridge rather than under the dial. Finally, the number of jewels is variable; many watches omit those on the third, fourth and escape wheels.

The hands are not shown here. The minute hand is fitted onto the squared end of the cannon pinion and the hour hand onto the hollowed boss of the hour-wheel. Where a second hand is present, it is mounted on an extension of the shaft (or arbor) of the fourth wheel.

*So called because originally both plates were completely circular. The removable barrel bridge, with a cut-out beneath it for the barrel, was Litherland’s innovation, adapted from a feature already found in chronometers in the previous decade.