While doing some research for the talk I noticed that nearly all of the lanterns depicted in the etchings and paintings from the 18th century that I came across, were round. There are numerous existing lanterns attributed to the 18th century, but it looks like, from this very un-statistical study, that round was the way to go.
In talking with other tinsmiths about this it was pointed out that it is easier to make a round lantern with the tools used in the 18th century than to make a square lantern. So maybe that is all there is to it.
Here is an example from Hogarth:
Here is an example from Diderot:
There are numerous examples on the Sifting the Past Blog showing round lanterns. In fact, of the 18 paintings from the 1700s showing lanterns, only one was not round.
Another thing I noticed is that in the different Hogarth prints that the round lanterns appeared to have narrow dividers compared to other round lanterns I have studied. So last weekend I set in and came up with a design influenced my the various period examples.
It is really a hybrid of a couple other lantern designs I have worked on, except that this lantern is about an inch more in diameter that my other round design interpretations.
Here is another view. Compare this to the Hogarth image above.
Now I am the first to point out that there is a large amount of speculation and "artistic license" taken with this design. But in my defense, Hogarth did not exactly show me much detail.
Who knows, maybe Hogarth thought, "you've seen one lantern......"
If you make it to the Convergence, and if you are a tinner you really should, stop by and let's talk lanterns.