Dr Fuller and I have discussed this on a couple of occasions, and I don’t recall that we came up with a definitive answer – I will try and remember to raise it with him next time we talk.
“Official” (typed rather than hand written) documents spell the word Thallasses, but also sometimes as Thalasses – e.g. see the RR et AC Constitution in my FB header.
We have some early copies of the Order’s Ceremonies (dated 1914) that came from the person tasked with burning the Order’s large collection of papers – the Temple’s last Cancellarius , David Osbourne 8=3. I can only speculate that he looked for and kept the earliest copies he could find before committing the rest to the fire. They spell the Temple name consistently as Smaragdum Thallasses, both typed, and in one case Amoun was crossed out and Thallasses hand written in, in a very tidy han also in a copy of the Equinox where Stella Matutina has been crossed out and Smaragdum Thallasses written in the same neat hand. We also have a copy of G1 that was issued to new members to tell them how to address each other, use of the official labels etc, and this has the spelling Thallasses also. I have posted images of these for interest.
Smaragdum appears to be Latin, meaning emerald, and Thallasses is Greek, meaning sea – it can be found transliterated with one “l” in Greek also.
Without the Warrant (which was either committed to the fire, or has yet to be found), the spelling cannot be confirmed either way it seems. Certainly the Warrant wording Howe published was clearly not from the actual Warrant, but from a typed draft (which Dr Fuller and I have both seen), that Felkin corrected in his hand writing in places – note that the “draft” spelt the word Thalasses which Felkin did not correct.
I, like my predecessors it’s seems, am guilty of spelling it both ways.
Kasmillos