Further tests in Horology's laboratory confirm the claims that the Elgin's Beryl-X balances have the hardness of steel. Thus the statement in last month's issue of Horology regarding the softness of all solid balances needs qualification.
It is apparent that the success of the grooved staff used with this new balance is due not only to its design but to the hardness of the balance arm as well.
From the name, appearance and properties it would seem that Beryl-X is a beryllium copper alloy, although the exact composition has not yet been published. Beryllium copper alloys can be hardened by heat treatment and are nonmagnetic and resistant to corrosion. They also make excellent springs and have a fatigue strength equal to spring steel.