British Type "R" Tube

The type "R" tube was produced by a number of manufacturers for the British military beginning in 1916 and throughout the remainder of WW-1.  It was a high-vacuum receiving tube that was based on the design of the French TM tube, with certain improvements.  The tube shown above was made by the British subsidiary of the General Electric Corporation (G.E.C.) under the Osram trade name.  Demand for these tubes was so great that they were also made by Moorhead, a US company.
This is a type "R" tube as made by the Royal Ediswan Electric Company, Ltd., an early electric lamp manufacturer.
  The bases on these tubes are typical of early European tubes.  They relied on the springiness of the split pins to achieve good contact with the socket.  American tubes used solid pins and relied on spring contacts in the sockets.  

The British military apparently specified a standard tube box design for the tubes they purchased.  The box shown here is for the type R tube as made by the Stearn Lamp Company.  The boxes for other suppliers were identical except for the manufacturer's name.