Daniel Gabriel Fahrenheit was the inventor of the mercury thermometer and creator of the temperature scale that bears his name. On the back of this thermometer — only the third original thermometer of his ever found — is an inscription in his handwriting of “Fahrenheit Amst”: his signature and the place where the thermometer was made, i.e., Amsterdam.
It actually looks like his autograph, too. It’s not just printed or engraved in generic font. Compare it to the signature on this May 7th, 1736 letter to Carl Linnaeus, the Swedish naturalist who invented the binomial system of taxonomy we still use today to identify plants and animals.