Paillard's non-magnetic compensating balance and hair-spring for watches
✍ Scribed by Edwin J. Houston
- Book ID
- 103090524
- Publisher
- Elsevier Science
- Year
- 1888
- Tongue
- English
- Weight
- 835 KB
- Volume
- 125
- Category
- Article
- ISSN
- 0016-0032
No coin nor oath required. For personal study only.
✦ Synopsis
BY paov. El)WIN J. Hous'roN.
Considerable ingenuity has been expended from very early times in the effbrt to produce a time-piece whose rate is sufficiently accurate for the determination of longitude. It was not, however, until about the middle of the eighteenth century that even approximate success was reached in this direction.
Trifling changes in the rate of movement of the balance-wheel of a watch make a considerable difference during a run of twentyfour hours. Taking five beats per second as the rate of movement existing in most watches, a variation of but the one-thousandth part of a vibration would make a variation of ninety seconds in each day.
The principal causes that tend to produce a variation in the rate of a well-constructed watch are as follows :
(I) Variations of temperature.
(2) Oxidation of the balance-wheel or the hair-spring.
(3) The influence of position on the balance-wheel.
(4) Variations in the force of recoil of tile hair-spring.
(5) Variations in the barometric pressure.
(6) Magnetic retardations or accelerations due to the influence of magnetism on the balance-wheel and the hair-spring.
The influence of changes of temperature on the rate of movement of the balance-wheel arises not only from variations in the distance between the point of support and the centre of oscillation of the balance-wheel, but also from variations in the elasticity of the hair-spring consequent on variations in temperature. A compensating balance-wheel, such for example as that first introduced by Harrison, although correctly proportioned to maintain constant the distance between the centre of oscillation and the point of support despite changes of temperature, would nevertheless be unable to rigorously maintain the same rate unless some device is employed to correct the variations in the elasticity of the hair-spring that accompany changes in temperature. Indeed the variation in the rate of the balance-wheel, due to these latter changes, is greater