Victor X-Ray Corp. Universal X-ray Tube (ca. 1923-1926)
This example of a Coolidge "Universal" X-ray tube was produced by the Victor X-Ray Corporation in Chicago. The close-up of the label etched onto the glass bulb (photo below left) indicates that this is a medium focus tube which was intended for general radiographic work. Note that the cathode filament of the medium focal spot tube forms a slightly conical spiral (photo below right).
The maximum high voltage for this tube would have been approximately 100,000 volts—this would be more or less equivalent to a 6" spark gap. The maximum rated current would have been approximately 40 milliamps for a 15 second exposure.
I am guessing that this tube dates from 1923-1926. This is based one of the patent dates etched on the glass (it appears to be October 1923 but is very difficult to make out), and the fact that Victor's parent company, General Electric, started phasing out the Victor name in 1926.
The following image shows the other example in the ORAU collection of a Victor Universal Tube. Unfortunately, it is impossible to make out the patent dates etched on the glass.