In 1911, Dr. C. E. Guillaume patented a nickel-steel alloy, Elinvar, whose elasticity remains practically unchanged with temperature changes, which eliminated the need for bimetallic compensation balances. However, the process of making rather complicated Elinvar springs was not uniform, and the springs did not always have the same thermal properties, leading to small variations in performance. To eliminate those variations and to enable temperature compensation even for small amounts, Paul Ditiheim designed and patented small bimetallic straps affixed to monometallic balances. Watches equipped with them are today very rare. Solvil was founded in early 1920 to exploit Ditisheim's invention, which offered an alternative to precision watches fitted with the more expensive Guillaume balances.A virtually identical watch is in the British Museum, illustrated in their Catalogue of Chronometers by Anthony G. Randall and Richard Good, plates 106 and 107.