Magnetised Watches.

Manawatu Standard, Volume IX, Issue 7, 6 December 1884, Page 1 (Supplement)

Magnetised Watches.

Since the introduction of the electric light, a great many good watches, especially those with English lever balances, have been ruined as time-keepers by magnetism induced m their steel parts, through the wearer going too near the poles of a dynamo machine. Professor G. Forbes, an electrician, had a gold chronometer watch, which formerly kept excellent time, so far destroyed as to lose several minutes a day ; and we hear of watches actually losing twenty minutes m the hour. Mr. Forbes investigated the cause of the losing rate, and found it due to the bar of the lever being magnetised, and also some iron screws m the works. Probably, too, the hair-spring was magnetic. The chronometer has been cured by removing the balance, springs, and screws, and substituting others of nonmagnetic metal. The balance is now of platinum-iridium (platinum-silver being too soft and subject to shocks) and the sprin gis of gold. Brass may be used for the screws, provided it is found to be non-magnetic, but some kinds of brass are magnetic, perhaps through admixture with iron. We may also mention that cases of soft iron were sold at the Vienna Electrical Exhibition, for the protection of existing watches ; the iron shell forming a magnetic screen or shield.