X-rays were discovered by Professor Wilhelm Roentgen in the autumn of 1895, and he announced the discovery at the end of that year. News of the discovery spread rapidly, and in February of 1896, about six weeks after the announcement by Roentgen, Professor Almy at Grinnell College successfully produced x-ray photographs.

The most common way of producing x-rays is by letting electrons moving at very high speeds strike a solid target. Professor Almy used a glass tube from which most of the air had been removed having two electrodes sealed into it, and an induction coil which produced a potential difference of several hundred thousand volts. When the coil was connected across the electrodes, electrons were accelerated to high speed and then sent into the positive electrode. Most of the energy of the electrons produced heat in the target, but a small amount of the energy went into x-rays, which sprayed from the tube.

Many pieces of commercial x-ray equipment have been given to the Physics Historical Museum over the years.