Nashville, Tenn., Jan. 10, 1898.
To the Editor:
—Though possibly it may already have been mentioned, I am not conversant with any report on what may be called X-ray blindness. During the Centennial Exposition here this summer there were several X ray machines in operation. One of these was attended by a gentleman of my acquaintance, of more than average intelligence and observation, and also possessed of a fair amount of electric knowledge. He tells me that out of about 3,500 persons who looked into the tungstate of calcium screen, at his hand or other object, four were unable to see anything. They were not only unable to see the bones of the hand or other objects more or less opaque to those rays, but they could not even distinguish the fluorescent light; the interior of the box was just as dark to them as before the light of the