In attempts to combat problems of magnetism, in the early 1800's, a few makers tried using glass in place of the steel balance spring and even in place of the balance. Most notably, the firms of Arnold & Dent and the house of Breguet experimented with glass in marine chronometers.
The springs took the form of helical springs and the balances were flat discs.
The advantages of using glass are as follows:
- Unaffected by magnetism
- Non corrosive
- Needs less compensation than steel
- Glass is cheap to make and more consistent in
mixing, as opposed to modern alloys.
- Less dense than steel and, in turn, less subject to
The disadvantages of using glass are as follows:
- Glass never fully solidifies. It is known as a
a "super cooled liquid," which means, as it remains
liquid in its formed state (balance spring) it is
subject to disintegration.
- It was difficult to fix the ends of the springs to
- Once formed, it is nearly impossible to adjust the
Anthony Randall, watchmaker, has been studying the effects of glass balance springs and has made several examples. One of which is shown here.
I will not go into details of his preliminary findings, as you can refer to the Horological Journal, June & July 2000 issues for his results.
I have seen one of his testing examples and it is amazing to see this glass, a material one would never believe could be used in this way, helical balance spring, oscillating in the same manner as all others I have seen.
Unfortunately, I don't have the time to properly research and present this topic, but I thought the forum would appreciate this unique application of material and creative thought in horology.
Anthony Randall, brass balance with Dent type compensation.
Marine chronometer no. 1771, EJ Dent, glass balance and balance spring with compensation pieces.