Blog: English Lever Bolt and Joint Cases

Date: 24 May 2023

I make additions and corrections to this web site frequently, but because they are buried somewhere on one of the pages the changes are not very noticeable. I decided to create this blog to highlight new material. Here below you will find part of one of the pages that is either completely new or I have recently changed or added to significantly.

The cases of hand made English watches used a method of fastening the movement to the case called “bolt and joint.” Because this is somewhat unusual, it may not be immediately obvious how to access the movement. This is described in the section below. The movement is usually the most impressive part of a hand made English watch, so it is a shame to leave it concealed. The method of opening might seem a bit unnerving at first, but the watches are quite robust and after you have done it a few times you will be popping the movement out to show to all your friend and family.

This entry is from the page about Watch Cases and Crowns.

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English Lever Bolt and Joint Cases

English Lever Double Bottom Bolt and Joint Case. Click image to enlarge

English pocket watches are often wound from the back and the hands set from the front, by a key applied directly to the square boss of the centre arbor which carries the minute hand. Because there has to be a hole in the back of the case for the key to enter, English lever watches usually have “double bottom” cases.

Winding from the back necessitates a hole in the case for the key, which must be normally covered to prevent dust getting in. This was the reason for the original pair case where the inner case of the pair had the hole, which was covered between windings by the outer case. Pair cases were not well sealed. The inner case carried the bezel and glass, the front opening in the outer case was open. This meant that dust and fluff could find its way into the outer case and between the two cases round to the winding hole. Nevertheless, pair cases continued to be made, mainly for watches with verge escapements, into the late nineteenth century.

When the English lever movement was developed around 1820, a better design than the pair case was also adopted. Like the earlier consular case, an outer bottom or back was attached to the middle part of the case by a joint. When this outer back is opened, it reveals the inner cover which is fixed to the middle part of the case. This inner cover has either a single hole for winding, or two holes if both winding and hand-setting are from the rear. In this case, the central hole is the one for hand setting.

The glass that protects the dial is held in a metal ring called a bezel, which is also attached to the middle part of the case by a joint.

Unlike the consular case, the joints for the back and bezel of an English lever case are separate and located at different positions around the middle part of the case. This made them simpler to make, with fewer knuckles, which allowed the joints to be made smaller and less obvious.

Bolt and Joint

The movement is attached to the middle part of the case by a bolt (catch) at 6 o'clock, which is circled in red in the image here, and a joint (hinge) below the pendant at 12 o'clock.

If the movement is to be examined or regulated, the movement is swung out from the front of the case by first opening the bezel and then releasing the bolt which holds the movement in place. The bezel is usually jointed to the middle part of the case at the side around 9 o'clock. To fully remove the movement from the case, the joint pin is pushed out, usually from left to right. This method of attaching the movement to the case continued in some high class English watches until about 1870.

When I first bought an English lever watch, I was told that this case was a consular case, but thanks to David Penney I now realise that this is not the correct name. In his book Watch and Clock Making, David Glasgow calls them double bottom cases and says that their cost was part of the reason for the decline of English watchmaking. Glasgow uses the term dome for an inner cover that is jointed (hinged) to the case and can be opened. This usage can also be found in the Horological Journal, so it is evident that at the time they were made this style of English lever watch case was called double bottomed. Here the terms outer and inner case back are used for the two bottoms.

In the photograph, the outer case back is open, showing part of the hallmarks for sterling silver. The inside of the hallmarked inner case back, which is fixed to the middle part of the case, is also visible. In this key wound and set watch the inner case back has a single hole for winding, which is isn't visible in the photograph. The hands are set by opening the front bezel and applying the key to the square boss of the minute hand.

English Lever Watch Cap - Slide the Blue Catch to Release: Click image to enlarge.

If a gold or silver watch case is to be hallmarked, the inner case back must be made of the same metal because, if it was not, none of the case would be hallmarked. English assay offices would refuse to hallmark an item that was not all of one standard of metal and the inner case back, which was rigidly fixed to the middle part of the case, the case band, was regarded as an integral part of the case.

Opening an English Lever Case

To open the case of an English lever watch, start by opening the front bezel, the hinged metal ring at the front which carries the crystal. Once the bezel is open, set the hands to 12 o'clock so that they are well out of the way.

Next, look at the dial below six o'clock. You will see at the edge of the dial a small piece of steel that is normally covered by the bezel. This small projection from the edge of the movement that I have ringed in red is the bolt (catch) that normally holds the movement in place. It has a horizontal slot on its outer side for a finger nail.

Press the bolt towards the centre of the dial with a finger or thumb nail. Be careful not to slip and catch the seconds hand. A small movement of the bolt will release the movement so that it can be swung out of the case on the joint (hinge) located at 12 o'clock below the pendant.

To release the movement from the case completely, the pin of the joint is pushed out, usually from left to right.

This method of holding the movement in place is called “bolt and joint.”

Removing the Cap

The movement is covered by a gold plated metal cap. It might seem logical to call this a dust cap, but the proper term for it is simply the cap.

The curved blue steel strip engages with two pillars on the movement (in the picture the lower one of these is missing) to hold the cap in place. It is fixed to the cap by the central rivet, which allows the strip to slide.

To release the cap, slide the blue steel strip round in the direction shown by the red arrows and the cap will then lift off. There is a peg at the middle of the strip where the middle red arrow is in the image. Use a finger nail to press against this peg.