It might be a false lead… the stuff from the correspondence-related sidebars cannot all be true:
They say it’s a series of confidential negotiations between the Masters and a devil of some note. [Unlikely, unless that devil never sent a copy of the negotiations to Hell.]
They say it comprises the billets-doux written by Jack-of-Smiles to the Traitor Empress. [VERY unlikely.]
They say it’s the letter the Pope wrote, the one without which Rome would have been the Fourth City.
They say if you read it your eyes boil and your hair turns the white of old ice. [Not true: your hair might catch fire, but it doesn’t turn white.]
They say it’s written on slate in the blood of poisoned bats.
They say it’s the language the bats speak. [Possible.]
They say the Snuffer wrote it on the outside walls of New Newgate. [Unlikely. I don’t recall any mention of sigils on New Newgate’s walls.]
They say the Topsy King learnt it, and that’s why you can never understand a bloody word he says. [True.]
They say it’s the mathematics of Hell. [Unlikely, unless they forgot their own mathematics.]
They say it’s the geography of Time. [Possible.]
They say it was invented wholesale by a honey-sipper sitting giggling in a cramped and filthy room on Hollow Street, and it’s been driving gullible scholars insane ever since.
They say it’s the key that opens Mr Stones’ vaults. [Possible.]
They say it’s concealed in Mr Pages’ library. [Possible.]
They say it’s the only way down here you can ever see starlight. [Possible.]
They say only the Brass Embassy knows. [No, they don’t.]
They say it’s the only map of all the Unterzee, scratched on the keystone of the Neath. [Possible.]
They say it predicts every price change in the Bazaar for the next hundred years. [Possible.]
They say it’s a script that you cannot write and live. [Unlikely, if it really was the language of Xanadu.]
They say every piece of deep amber has a fragment of the Correspondence at its heart. [Possible.]
They say it’s a gate that opens in the stalactites behind Wolfstack Docks.
They say you can see it in Mrs Plenty’s mirrors.
They say it’s the only sure way to tell the weight of your soul. [Possible.]
They say it’s the map that connects every glimmer of moonish light to a star. [Possible.]
They say it’s the key that unlocks the secrets of bat-flights. [Possible.]
They say it’s a trap that someone found inscribed on a wall in the First City, and if you decode its complicated patterns you inevitably decide you’re God, to the considerable detriment of your social life. [Possible.]
They say it’s the letters that Helen wrote to Menelaus in the years of her imprisonment. [Unlikely, though the Correspondence would be a tragical love story, then.]
They say it’s the last accounts of the last days of the Third City, strung in beads on cord in a code no-one living understands… [Unlikely, as the Third City was Mayan, not Inca. Only the Incas used Quipu. The Mayans had a hieroglyphic script.]
I don’t think the Masters would’ve seen Rome as a likely candidate for Fourth City, anyway. The Fourth City was acquired in the 14th century - Rome was not particularly powerful back then (http://en.wikipedia.org/wiki/Rome#Middle_Ages).
Also, not a single one of the sidebars hints to the Second City, which I think is where the Correspondence was invented/discovered. (Mr Eaten’s name is a Correspondence sigil, after all…)
There’s also this:
They say it’s the letters Raffles wrote about the Cat that never were published.
Unlikely, though very interesting in another matter:
A letter fragment, dated Singapore, 1821
"I have, I fear, at last determined the cause of our poor Leopold’s sad disappearance. You will recall that I sent by the Borneo a very considerable collection of [illegible] … identified one variety as the sinister exile’s rose of the Bosphorus. Sophia had long admired their colour [illegible] … gardens here about the Government-house [illegible] … although here they call it ‘lion’s rose’. Singapura is Lion City in the Sanskrit [illegible] … There are of course no lions here, though many tigers. I would not mention this except that when I dream of Leopold, as still I often do, it has always seemed to me that there is a great cat present, the colour of sunset, which is also the colour of the roses…"
Compare:
"Personal tragedies started for Raffles. His eldest son, Leopold, died during an epidemic on 4 July 1821. The oldest daughter, Charlotte, was also sick with dysentery by the end of the year, but it would be his youngest son, Stamford Marsden, who would perish first with the disease, 3 January 1822, with Charlotte to follow ten days later. […] As Raffles grew restless and depressed, he decided to visit Singapore before heading home to England. Accompanying him would be his wife Sophia and their only surviving child, Ella. […] Raffles was a founder (in 1825) and first president (elected April 1826) of the Zoological Society of London and the London Zoo."
[from wikipedia: Stamford Raffles - Wikipedia]
edited by Rupho Schartenhauer on 3/24/2015