EARLY COSSOR RECTIFIER TUBE, 1900's

An early rectifier tube that has been over driven by Mr Lee, Causing an element to drop, before he donated it to the museum. On the top is a pillar containing Asbestos which when charged by high voltage re-gassed the tube.

The firm A.C.Cossor Ltd was established in 1859, making Scientific glassware.
Cossor Electronics started in 1875.

Your comments:

• This is a high-tension rectifier. Its purpose is to restrict the flow of current through an X-ray tube to one direction, from the cathode to the anode, in order to protect the tube against reverse currents (inverse discharges) that would flow from the X-ray tube's anode to its cathode. Having X-rays originating from both the anode and cathode could be disastrous in radiography because the resulting X-ray images would be blurry. The valve tube is connected in series between the X-ray tube and the high voltage source.
  
  The valve consists of a long aluminium funnel and a curved mirror. Experience has shown that when the mirror is negative, the valve will be, virtually, closed to currents. In the next half cycle, when the funnel is negative, a strong beam of electrons will be sent against the mirror.
  
  This form of valve is very efficient, but the gas pressure has a tendency to decrease somewhat rapidly. Hence the need for a regulator, so that regulation is possible as often as desired.
  
  A tube of similar construction was produced by the French company PILON:
  lampes-et-tubes.info/xr/xr059.php
  .......... Giorgio Basile, Nivelles, Belgium, 28th of August 2026
  
  

A0639