How do you tell if a shoe is a good fit? Take a short walk? Squeeze the front-end with your fingers to make sure there is space for your toes? What about a dangerous, 20-second blast of unshielded ...

Many of the greatest scientific discoveries are eventually changed and adapted for more practical and widespread use. Since its discovery by Wilhelm Roentgen in 1895, the use of the X-ray has become ...

A detail from a department store ad from The Washington Post in the 1930s.The ads touted the X-ray machines used to fit shoes for children. Such machines were common until the 1950s. (The Washington ...