This next part is crazy. I don’t know how Harrison dreamed up this idea. I don’t know how it’s even possible. Maybe a reader with experience in welding can help me out.*
Because metal springs are susceptible to temperature changes, which make them less reliable and accurate, Harrison invented the bimetallic strip. It is 2 metals, like steel and brass, welded together.
Did you get that? It’s possible to weld, or fuse, or something, steel and brass now. The watch’s mainspring needs always to be springy. When it’s cold, the spring becomes too stiff. When it’s hot, the spring becomes too loose. Harrison fused two metals together—steel and brass—in a spring. If the steel were too tight, the brass would keep it loose. If the brass were too loose, the steel would tighten it up. This way the spring would keep the same springiness no matter the temperature.
* This weekend I had the pleasure of consulting 2 engineers, my sister’s boyfriend Dave and my nephew Andrew. They tell me with enough heat, two different metals can be fused together. The two metals would be hammered together many times under heat until they were one. Andrew added that it’s only air molecules that keep metals from fusing together in the first place.
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