"The Eye of Osiris" is a novel written by Richard Austin Freeman (1862 - 1943). He was a British writer of detective stories, mostly featuring the medico-legal forensic investigator Dr Thorndyke. A large proportion of the Dr Thorndyke stories involve genuine points of scientific knowledge, from areas such as tropical medicine, metallurgy and toxicology. In this crime novel, Dr Thorndyke solved the mistery using a X-ray photography of a mummy.
"It was all clear enough so far. The peculiar sound that filled the air was the hum of the interrupter; the bulb was, of course, a Crookes' tube, and the red spot inside it, the glowing red-hot disc of the anti-cathode. Clearly an X-ray photograph was being made; but of what? I strained my eyes, peering into the gloom at the foot of the gallows, but though I could make out an elongated object lying on the floor directly under the bulb, I could not resolve the dimly seen shape into anything recognisable. Presently, however, Dr. Norbury supplied the clue. 'I am rather surprised,' said he, 'that you chose so composite an object as a mummy to begin on. I should have thought that a simpler object, such as a coffin or a wooden figure, would have been more instructive.' "