Here's a couple of terms found in the glossary of the "Lighthouses of Ireland" guide I was lucky enough to win in Mombo's St. Paddy's Day post card lottery:

Can you tell what they mean?

Murrett

Occulting

Extra Credit: What's the difference between a Parapet and a Gallery, as related to a lighthouse?

I don't know murret, but occulting means is periodically darkened. A light that goes on and off is occulting. I believe it is only occulting if there is more light than dark, otherwise it is flashing.

And...a shot in the dark...the diference between a parapet and a gallery is that a gallery hangs over the edge of the light, while a parapet rests on top of the tower with little or no overhang.

Good one, Greg...

You got the occulting right -- more 'on' than off.

Parapet and Gallery -- not right, although I think this is a fine difference in lighthouses only.

Murrett - still up for grabs, folks.

OK...let me try parapet/gallery again. Another stroke of genius...

the parapet is the watch room balcony. The gallery is the one around the lantern room. Or vice versa.

It's the vice-versa version.

John,

I went into my library and may have found a copy of the book you won, Irish Lighthouses by Sharma Krauskopf who, by the way, I had an opportunity to correspond with a year or so ago. Anyway, the book describes the murrett as "the part of the lantern house between the balcony and the glass usually made of concrete or steel".

Accurate?

Gary

You got it, Gary...

So, the murrett is that section of lantern room assembly that is solid but vertical below the glass. This, I believe, is more common on lights with smaller-order Fresnels, because there is no need for glass down there.