A 1927 trade journal article describes the lamps that Westmoreland made at that time, such as lamps with glass bases for "water lamps". These table and boudoir lamps included several of the English Hobnail pattern that could be used as oil lamps or as electric lamps. Westmoreland shipped an electric socket attachment with each lamp. These water lamps had hollow bases which could be filled with colored water, especially the crystal ones. Personally, I think I would like them better without the water.
This hollow Westmoreland lamp base is 9" tall and 4" across the base. The round bulb at the top is also 4" across. The opening at the top is 1". This beautiful pink lamp is in excellent condition with no issues.
Westmoreland Pink English Hobnail Water Lamp Base