Hi

Last year I purchased a number of mid 19th century lighthouse lenses (not bulbs) in an auction, also included in the lot were several individually boxed old lamps labelled as Siemens projector lamps. The prisms had been purchased by the previous owner in the late 1960s from the Northern Lighthouse Board who look after the lighthouses in Scotland. My first query would be whether these bulbs have any connection to lighthouses at all, if they have any value, and lastly if they have a value a rough idea what that would be?

One member of your group did advise previously the following
The lamps in your lot are not really for land-based lighthouses, but were used on ships.  They have a special metal base known as the Sperry Block, and are probably rated something like 80V 1500W or 80V 2000W.  They were intended for use on large battery power supplies and as far as I know, were used for mobile signals.  Normally, lighthouse lamps have a circular filament arrangement and are intended for producing a wide beam of light visible all around the horizon.  The Sperry lamps instead have a planar grid filament and seem to have been more optimised to aim the light only in a particular direction.

Anyway any advice greatly received!