Many home cooks and grill masters cook up their steaks and hamburger patties using the old-fashioned eyeball test. This is when you flip the patty after it turns brown and grill marks start appearing.

If you're using a meat thermometer to ensure your food is done, you're only halfway to avoiding safety issues. You also need to know how to clean it correctly.

Air thermoscope and air thermometer -- The invention of the liquid-in-glass thermometer -- Seventeenth-century developments -- The search for rational scales -- Difficulties and refinements -- Maximum ...