Hello Bryan
The range and style of stern lanterns was quite varied, particularly on non English ships, did you have a particular vessel in mind?
As far as English lanterns were concerned:
Early 17th century lanterns were usually hexagonal in plan with parallel sides.
Around the middle of the century spherical lanterns made an appearance and made up the most common type, made up of scores of tiny panels of mica glass which had a rather opaque quality.
By the late 17th century (1690) larger panes of glass became available and parallel hexagonal lanterns came into use again. By the early 18th century the standard hexagonal shape was established where the base was narrower than the top, and had a curved roof carrying some decoration. This remained the norm on English ships until the 19th century.
French, Dutch, and Spanish lanterns tended to be more ornate than English ones.
The size of lanterns tended to reduce in the later periods but it was said of the ‘Sovereign of the Seas’ that a man could stand up inside her main lantern. By comparison the Centre lantern of Victory stood about 4.5 feet in height.
The lanterns were lit by use of large candles or perhaps whale oil.
Jean Boudriot writing in his major work ‘The Seventy Four Gun ship’ decribes the stern lantern thus:
It is made of tinplate with the base of wood, panes fit into little channels in the tin plate, and it is lit by a single fat candle of yellow wax.
The exterior may be gilded or more likely painted.
The large stern lanterns were of use when sailing in a fleet at night allowing ships astern to keep station.
The centre lantern was usually only lit by the Flagship.
I hope this brief summary is of some help, apart from pictures on models and the like, and drawings relating to specific ships (Victory) I only have a few line drawings of lantern styles. If you let me have your email address I will send you what I have.
Regards