Compensation of Temperature and Chronometers
The view of watches as scientific devices brought rapid advancement to their mechanism. During the same period, the development of accurate marine chronometers to determine longitude produced technical advancement and such the advancement later used in watches.
Later on, it was found that in the balance wheel, a major cause of the error was a change in elasticity. This problem was solved by the temperature compensated balance wheel was invented in 1765 and this was invented by Pierre Le Roy and it was improved by Thomas Earnshaw.
This type of balance wheel was having two semicircular arms that were of bimetallic construction. In this type, if this temperature rises, the arms bend inward slightly causing the wheel to rotate faster back and forth.
Such the temperature which could reduce temperature and also induced errors to a few seconds per day, with the passage of time gradually began to be used in watches over the next several years.
Complicated pocket watches and astronomical watches with many functions and features were made during this period.
The Invention of Lever Escapement
This lever escapement, invented by Thomas Mudge in the year of 1759 and it was improved by Josiah Emery in the year of 1785 and Lever escapement gradually came into use from about 1800 onwards, chiefly in Britain. After some time, it was also adopted by Abraham-Louis.
By about 1900, the Lever was almost used in each and every type of watch made. In the Escapement, the escape wheel pushed on the T shaped lever which gave the wheel a specific push before releasing it.
The benefit of the lever was that it allowed the balance wheel to swing freely during most of its cycle. These types of watches were self-starting, so if the balance wheel was stopped then it would start again.
In the year 1702, Jewel bearings introduced quality watches in England. Watches of that period are characterized by their thinness. Latest innovation like as Lever escapement and cylinder allowed watches to become the watches much thinner than they had been in the past some years. This also caused a change in styles.
The thick pocket watches were thick and were based on the verge movement and it was also out of fashion at that time. Hence, such the watches are worn by the poor and were derisively referred to as ‘turnips’ and ‘onions’.
Accuracy in watches occurred in the year 1657 with the addition of balance spring. This balance spring was attached to a balance wheel. The balance spring made the wheel a harmonic oscillator. Balance spring not only increased the accuracy but also reduced the errors of several hours per day.
The first thing that really improved with the help of balance spring was escapement. Cylinder escapement was invented by Thomas Tompion. The advantage of these escapements was that they gave a balanced push in the middle of the watch’s wing.
During this century, Robert Hooke allowed increasing in the production of the watch. The finishing and assembling were done in the 19th century only by hands.