Balance Spring - Effect of Temperature

Effect of Temperature

The modulus of elasticity of materials is dependent on temperature. For most materials, this temperature coefficient is large enough that variations in temperature significantly affect the timekeeping of a balance wheel and balance spring. The earliest makers of watches with balance springs, such as Robert Hooke and Christian Huygens observed this effect without finding a solution to it.

John Harrison, in the course of his development of the marine chronometer, solved the problem by a "compensation curb" – essentially a bimetallic thermometer which adjusted the effective length of the balance spring as a function of temperature. While this scheme worked well enough to allow Harrison to meet the standards set by the Longitude Act, it was not widely adopted.

Around 1765, Pierre Le Roy (son of Julien Le Roy) invented the compensation balance, which became the standard approach for temperature compensation in watches and chronometers. In this approach, the shape of the balance is altered, or adjusting weights are moved on the spokes or rim of the balance, by a temperature-sensitive mechanism. This changes the moment of inertia of the balance wheel, and the change is adjusted such that it compensates for the change in modulus of elasticity of the balance spring. The compensating balance design of Thomas Earnshaw, which consists simply of a balance wheel with bimetallic rim, became the standard solution for temperature compensation.

Read more about this topic:  Balance Spring

Famous quotes containing the words effect of, effect and/or temperature:

    A readiness to believe ill of others, before we have duly examined it, is the effect of laziness and pride. We are eager to find a culprit, and loath to give ourselves the trouble of examining the crime.
    François, Duc De La Rochefoucauld (1613–1680)

    A readiness to believe ill of others, before we have duly examined it, is the effect of laziness and pride. We are eager to find a culprit, and loath to give ourselves the trouble of examining the crime.
    François, Duc De La Rochefoucauld (1613–1680)

    This pond never breaks up so soon as the others in this neighborhood, on account both of its greater depth and its having no stream passing through it to melt or wear away the ice.... It indicates better than any water hereabouts the absolute progress of the season, being least affected by transient changes of temperature. A severe cold of a few days’ duration in March may very much retard the opening of the former ponds, while the temperature of Walden increases almost uninterruptedly.
    Henry David Thoreau (1817–1862)