An eye blister is a benign growth which can appear on the whites of the eyes or on the cornea itself. There are two main types of eye blister: pinguecula and pterygium.
Before x ray machines were invented, broken bones, tumors and the location of bullets were all diagnosed by physical examination and a doctor's best guess. Patients paid the price of these approaches. Then on November 8th of 1895, a German physics professor Wilhelm Conrad Roentgen made a remarkable discovery.
The discovery of the structure of DNA by James Watson and Francis Crick in 1953 is one of the most famous scientific discoveries of all time. X-ray diffraction of DNA crystals results in a cross shape on the X-ray film, which is typical of a molecule with a helix shape.