The most important thing to know about Fresnel lenses, before casually attempting to drop them into conversation, has to do with phonetics: "Fresnel" is pronounced "Fruh-NEL." If the silent "S" makes ...
Traffic lights have been with us since 1868, when the first gas-powered set was switched on in London. These lights used a semaphore system similar to those used by the railways of the day and ...
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