Piffard Safety X-ray Tube with Heavy Anode (ca. 1910)


This is the “heavy anode” version of the Piffard tube. For an explanation of its various components, check out the description of the collection’s light anode Piffard tube.


Perhaps the most important characteristic of this "safety" tube was the fact that it did not need an enclosing shield. Shielding was unnecessary because the tube was entirely made of lead glass (except for the thin window of soda glass fused onto the end of the extension in front of the target).



Quoting Sinclair Tousey: "This tube was intended primarily for the treatment of skin lesions with the x-ray, but it can also be used for light fluoroscopic work and radiography."

Piffard designed the tube so that it would have a relatively large volume - the larger the volume, the slower the inevitable change in the degree of vacuum. This mitigated long-term changes, whereas an adjustment to the gas pressure made with the tube’s regulator was a short-term fix. Presumably, the dual bulb design came about because it was difficult to manufacture¬†a single large bulb whose glass was thick enough to shield the x-rays. Here is another possible explanation: having two small bulbs rather than one large one made it possible to position the patient closer to the target.

This particular tube belonged to M. J. Gross who worked with Dr. Coolidge at General Electric in Schenectady N.Y.  Gross later became Vice President of the GE X-ray Company. During the 1930s and 1940s, Gross and Zed Attlee formed the core of Coolidge's research and design team.

Although there are no identifying markings on the tube, it was probably manufactured by Machlett & Son.

Kindly donated by Linda Sinrod in memory of Malvern J Gross

Size:  approximately 16" long with 3 1/2" bulb diameter


Grigg, E. R. N. The Trail of the Invisible Light. Charles C Thomas. 1965.

Tousey, S.  Medical Electricity, Rontgen Rays and Radium. W. B. Saunders Co. 1916.

X-ray Tubes               Museum Directory

Last updated: 11/07/07
Copyright 1999, Oak Ridge Associated Universities