Applying the Chatillon iso-elastic springs to the Mount Rose spring balance

Temperature variations affecting the elasticity, creep and hysteresis of the metal of the springs and deviations from the shape in the stresses and transmitting machinery cause inaccuracies in spring scales. A new spring developed by J. Chatillon and Sons, made of an alloy called Iso-Elastic Metal eliminated the effects of temperature changes in the spring. The creep at stress of 60,000 lbs/sq in was reduced to less than 0.02% in deflection. The hysteresis was not over 0.02-0.04% of the full load deflection. A linear relationship of spring between load and deflection was obtained by using wire coiled with the axis of the wire parallel to the axis of the helix. Iso-Elastic springs were used in a Chatillon spring scale weighing 6 lbs, 5 oz. which gave an accuracy of 99.92%. A Mount Rose type of spring balance scale weighing 2 lbs. 12 oz. was constructed using Iso-Elastic springs. Further development of the scales is necessary to reduce it in size and weight before it can be used for snow surveys.