The Eye of Osiris

"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.' "
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The novel is named from an Egyptian symbol, the Eye of Horus.
The Eye of Horus is an ancient Egyptian symbol of protection, royal power and good health. The eye is personified in the goddess Wadjet. The name Wadjet is derived from 'wadj' meaning 'green' hence 'the green one' and was known to the Greeks and Romans as 'uraeus' from the Egyptian 'iaret' meaning 'risen one' from the image of a cobra rising up in protection. More at Wiki
Wadjet was one of the earliest of Egyptian deities who later became associated with other goddesses such as Bast, Mut, and Hathor, who is also depicted with this eye. Burial amulets were often made in the shape of the Eye of Horus, to protect the owner in the afterlife and to ward off evil. Ancient Egyptian and Near Eastern sailors would frequently paint the symbol on the bow of their vessel to ensure safe sea travel (Charles Freeman, The Legacy of Ancient Egypt, Facts on File, Inc. 1997. p.91).
"Horus was the ancient Egyptian sky god who was usually depicted as a falcon. His right eye was associated with the sun Ra. The eye symbol represents the marking around a Peregrine Falcon's eye that includes the "teardrop" marking sometimes found below the eye."
It is interesting to note that, in the ancient egyptian calculus, the Eye Of Horus defined number one (1) = 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64, by throwing away 1/64. The parts of the Eye were used to represent fractions.

Amulets on display at the Egyptian Museum, Torino