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.   hunkin




Victorian nanotech
Part two

While I was working on my aunt’s pocket watch, my tutor Ian showed me some of his other watches. The very first watches appeared in the 1500s and apart from the addition of the balance spring, their basic design didn’t change much until the 19th century. Then they went through a revolution - by 1850 the verge escapement was obsolete, replaced by the lever escapement.

Verge escapement

Lever escapement

The lever escapement solved a major problem. In a verge escapement the balance wheel is always  in contact with the watch gearing, so any slight changes in friction of anything in the watch influences the balance wheel. The genius of the lever escapement is that the balance wheel (omitted from the shaft on the right of the drawing above) is completely detached from the rest of the watch, except at the midpoint of its swing when it releases the ‘lever’ and moves the escape wheel to the next position (making the tick sound). It’s so much better that it doesn’t need a fusee like the one inside my aunt’s watch – a lever escapement will keep time whatever the spring tension.


Shortly after the lever escapement was introduced, an American engineer called Aaron Dennison developed the first machines to mass produce watch parts. At first his companies kept going bankrupt, but somehow the same machines would reappear in the next company. Eventually named the Waltham watch company, it   became well established and continued to produce millions of watches until the 1950s. Waltham were really proud of their achievements, and felt that machine made watches, with interchangeable parts were ‘scientific’ and greatly superior to European hand made ones. Their pride is very evident in the elaborate decoration of their watch movements.

I bought a beautiful Waltham pocket watch on Ebay for about £100 (a model 645, made in 1908) to take to bits. I thought it was a hopeless case because I couldn’t pull out the winder to change the time.  Ian immediately solved this problem. It was classed as a railway watch, and one of the railway specifications was that it must be impossible to change the time accidentally. So, instead of pulling out the winder, the dial cover had to be unscrewed and a tiny lever pulled out. Then the winder moved the hands perfectly.  


Instead of two thin ‘watch plates’, a Waltham watch is made of thick nickel alloy plates, with spaces milled out to accommodate the gears. All the screws go in much further and everything feels satisfyingly solid. It’s a joy discovering how carefully every detail is designed.


My watch had 21 jewels (pale pink rubies). Most of them could stay in place but the balance wheel and escape wheel had a double jewel on each end. One with a hole as the bearing and one plain disk as an end plate, or thrust bearing. These had to be taken out as dirt gets in the gap between the two. After cleaning everything we realised we had lost track of which jewel went where, a bad case of divided responsibility. It took hours inspecting them all under a microscope and trying them in different places.


Eventually we got the jewels in the right positions. The satisfying thing about a lever escapement is it starts ticking enthusiastically immediately the balance wheel is in place. Sadly it doesn’t keep ticking for a full day, and is only accurate if it’s kept flat. Ian is confident he could he could get it to work properly with enough effort, but still not bad for a 100 year old watch. 

Pocket watches were gradually superseded by wrist watches in the early 20th century. The movements were exactly the same, but half the size. The first digital watch was made by the Hamilton watch company in 1972. It had an LED display that only lit when a button was pressed for a few seconds to avoid draining the batteries. The enthusiasm for digital displays didn’t last. Today’s dial watches are electronic and battery powered (the first watch of this type was introduced by Seiko in 1969). The hands are driven by a stepper motor, and the timing is controlled by a quartz crystal. ‘Quartz’ watches are typically accurate to within half a second a day, about 10 times more accurate than any mechanical one. 

Now almost everyone has a mobile phone, there’s no need to have a watch at all, so all today’s watches are basically jewellery. Simple quartz watches are now amazingly cheap. Mechanical watches are also still made, but it’s a strange business. At one end of the scale the Chinese mechanical watches on ebay cost less than £10. I bought one and it keeps good time. The Swiss watches that feature in glossy magazine adverts (often costing over £10,000) also have traditional lever escapements. They are beautifully made and every part is hand polished, but it is weird that people spend that much on a watch that is less accurate than a simple quartz watch. 




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