Anibal (acier au nickel pour balanciers); an alloy invented by Dr. Charles Edouard Guillaume, exhibits unusual properties both in terms of thermal expansion and in changes to elasticity. These properties are very different from the two other famous alloys invented by Guillaume: Invar and Elinvar. Around 1900, Guillaume attempted to eliminate the so-called "Middle Temperature Error" caused by the change of rate in a timekeeper with a steel-brass bimetallic balance as being approximately a linear function of temperature, while the change of rate caused by change in elasticity of a balance spring as being approximately a quadratic function. As equal to zero at only two temperatures, this causes secondary error. Countless attempts were made to eliminate "Middle Temperature Error", usually by means of auxiliary compensation devices. In 1899, Guillaume noticed that steel with an addition of 44.4% nickel had a negative square coefficient of thermal expansion. This alloy, combined with brass in bimetallic lamina makes its expansion close to quadratic. Balances with bimetallic rims made of anibal and brass are usually called Guillaume balances, or, as their inventor called them, integral balances. When combined with special balance springs, they exhibit remarkable temperature stability on occasion not exceeding 1/50 second per day at 1° C. To be sold without reserve