Reconstruction of a 1770-1780 James Cox pocket watch

James Cox, an English manufacturer, was one of the most famous English watchmakers of that era. The quality that James Cox gave to his work was well above the standards of the time. He mainly worked for the Chinese and Indian markets, making complicated watches and automata like the one for the Emperor Quianlong. This quality was not just reserved for his highly elaborate gold and rock crystal boxes but also made his mechanisms exceptional.

At that time his balance wheels were made of gold not steel, which was unusual in 18th century lever escapements. The coq (the pierced and engraved upper bridge of the balance assembly) has a great quality and finish; it is possibly that best one I have ever seen. The thinness, delicacy and size of his gears was also beyond the skills of most watchmakers of the time, as he made miniature watches 1.5 cm in diameter, like the one described in this post.

The watch was given to me to repair in a really bad state of repair, with the lower bridge of the escapement and the balance wheel broken, one balance pinion not working, broken and twisted teeth on the escape wheel, a loose upper plate, non-original parts and screws that had completely lost their thread. Given the condition of the watch, this antique pocket watch reconstruction was extremely complicated, although it was also one of the most rewarding of my career.

The first thing I did to tackle this project was to solve the attachment of the upper plate: the plate is held on by three pins that go through the posts and on each of them the head was broken where the hole is. The upper plate was cut and attached in only two places and when the spring was wound the plate lifted up and made the crown wheel and escape wheel disengage, leading to errors and teeth being missed, which caused problems with the escape wheel. James Cox, an English manufacturer, was one of the most famous English watchmakers of that era. The quality that James Cox gave to his work was well above the standards of the time. He mainly worked for the Chinese and Indian markets, making complicated watches and automata like the one for the Emperor Quianlong. This quality was not just reserved for his highly elaborate gold and rock crystal boxes but also made his mechanisms exceptional.

To solve this problem, without soldering and avoiding changing the colour and losing the gold colour to the mercury, I drilled the post and cut a 0.70 mm thread. Then I countersunk the upper plate to put in a flat headed screw and attach the plate properly, without any soldering and trying to keep it as close to the original as possible.

After this, I repaired the balance wheel and the broken escape wheel, which had been soldered several times, to try to put them in the correct position. The brass of the soldering had been eaten away and the attachment pins had also been cut. On putting the broken part in place, it was obvious that material was missing as it would not remain flat and in position. Soldering it and adding more heat and tin was not feasible as it could not be put in place. The solution was to use slow drying epoxy resin, which allowed me to place the broken part in position and also to position new bridge attachment pins, which were now held in place with pins and a screw. This cold weld is invisible and only a thin line can be seen, so that it respects the original bridge. I also changed the bearing of the escape wheel as it was badly scratched and in very bad condition.

The next step was to repair the crown wheel, which, because of its size, has very fine, delicate teeth. Several teeth were bent and the wheel was not flat so I straightened the teeth and flattened the wheel. The escape wheel is very small and its teeth were very damaged and misshapen. On the lathe, I corrected the tops of the teeth to make them equal and then ground them using an aluminium oxide and synthetic ruby stone, which polishes as it wears the surface down. The aluminium oxide and ruby stone was made to measure using a diamond stone, which allowed me to correct the tiny teeth on the escape wheel one by one.

The next step, one of the most complicated, was to fit a pallet balance wheel staff to this escapement at this height and to the original gold balance wheel. It was a long, delicate task to create a uniform escapement. First of all, the mainspring was replaced with a weaker one 0.10 mm thick. The one that had been attached was too strong and possibly was the reason that the chain broke. Next, the fusee chain was repaired, all the screws were made and blued, and new threads cut.

The hands on this watch are gold and in the shape of an arrow. As it only had the hour hand, I made a gold minute hand with the same shape, with a square setting for setting the time.

Although this is a very early watch, its quality is very high, which is not usual in pallet watches of this era. Its quality and its small size and delicacy make it a very special, much sought-after watch with a very high value and of great interest to top-of-the-line collectors.

Managing to get such old, badly damaged mechanisms to work again is my passion and my stimulus. I can’t compare it with any other kind of repair because of the satisfaction it gives me. If you think about how this watch was made at a time when there was no electric light, no computers, etc. and you see what people were capable of doing with their hands, a few basic tools, mathematics and a lot of time, I can only take my hat off to these master craftsmen and appreciate the work that they did.