—I’ll answer it, the professor said, going.

—B is parkgate. Good.

His finger leaped and struck point after point, vibrating.

—T is viceregal lodge. C is where murder took place. K is Knockmaroon gate.

The loose flesh of his neck shook like a cock’s wattles. An illstarched dicky jutted up and with a rude gesture he thrust it back into his waistcoat.

—Hello? Evening Telegraph here… Hello?… Who’s there?… Yes… Yes… Yes.

—F to P is the route Skin-the-Goat drove the car for an alibi, Inchicore, Roundtown, Windy Arbour, Palmerston Park, Ranelagh. F.A.B.P. Got that? X is Davy’s publichouse in upper Leeson street.

The professor came to the inner door.

—Bloom is at the telephone, he said.

—Tell him go to hell, the editor said promptly. X is Davy’s publichouse, see?

I couldn’t figure out what Myles Crawford was talking about in this passage until I found an excerpt from the book Joyce: A Guide for the Perplexed by Peter Mahon. He explains that Crawford is seemingly arbitrarily decoding an old coffee ad as some kind of secret map Gallaher left detailing the murders in Phoenix Park. He also goes on to explain that perhaps this is an invitation from Joyce to us to look at his text in this non linear code, that or perhaps a way of playing a trick on us to get us to look for some kind of meaning that isn’t actually there. I will leave that up to the experts. (source)