Were Guillaume's alloys truly 'invariant'?
The term 'invariant' in my work should be understood within its practical context. When I spoke of invariant alloys, I was referring to materials exhibiting an exceptionally low, or nearly zero, coefficient of thermal expansion within specific temperature ranges. It's not an absolute, unchanging property across all conditions, but rather a remarkable stability compared to ordinary materials. We seek the invariant in nature, yes, but sometimes we can engineer it, bringing it closer to practical application. The goal was to minimize the 'slop' – the unwanted expansion or contraction – that plagues precise instruments.
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