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Clarence Madison Dally

Clarence Madison Dally (1865-1904) was an American glassblower, noted as an assistant to Thomas Edison in his work on X-rays and as an early victim of radiodermatitis and its complications.


Early life and education

Clarence Dally was born in Woodbridge, New Jersey, one of four brothers. He enlisted in the US Navy at the age of seventeen where he served for six years.


After obtaining an honorable discharge he went to work at the Edison Lamp Works in Harrison with his father and brothers as a glassblower. Around 1890 he moved to the Edison Laboratory in West Orange to assist in experiments with the incandescent lamp.

Edison X-ray focus tube

Following Röntgen's discovery of X-rays in 1895, Clarence and his brother Charles worked on the development of the Edison X-ray focus tube. At the time, the levels of X-rays produced were not believed to be dangerous, however Edison noted how "the x-ray had affected poisonously my assistant, Mr. Dally."

Radiation effects

By 1900, Clarence Dally was suffering radiation damage to his hands and face sufficient to require time off work. In 1902, one lesion on his left wrist was treated unsuccessfully with multiple skin grafts and eventually his left hand was amputated. An ulceration on his right hand necessitated the amputation of four fingers.

These procedures failed to halt the progression of his carcinoma, and despite the amputation of his arms at the elbow and shoulder, he died from mediastinal cancer. Following this, Thomas Edison abandoned his research on X-rays.


  • Percy Brown, American Martyrs to the Roentgen Rays, 1936, reprinted in American Journal of Roentgenology, 1995 [1]
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Clarence_Madison_Dally". A list of authors is available in Wikipedia.
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