There's a touching passage in James Joyce's Ulysses -- let me pay homage to the inventor of the weblog and link to Jorn Barger's Joyce pages -- when Leopold Bloom is walking through Dublin on 16 June 1904, thinking in quick alternation, as he is prone to do, about his own miseries and about the immediate impressions on his sensorium:
Mr Bloom moved forward raising his troubled eyes. Think no more about that. After one. Timeball on the ballast office is down. Dunsink time. Fascinating little book that is of Sir Robert Ball's. Parallax. I never exactly understood. There's a priest. Could ask him. Par it's Greek: parallel, parallax.
"Dunsink" is the Dunsink Observatory, in what was then the outskirts of Dublin. The Ballast Office "timeball," atop the clock proper, would drop on the hour, enabling Dubliners and visitors to set their watches. Bloom notes it as he passes, but then his mind, prompted by other stimuli, moves on to other things. A few minutes later, though, he circles back:
Now that I come to think of it, that ball falls at Greenwich time. It's the clock is worked by an electric wire from Dunsink. Must go out there some first Saturday of the month. If I could get an introduction to professor Joly or learn up something about his family. That would do to: man always feels complimented. Flattery where least expected. Nobleman proud to be descended from some king's mistress. His foremother. Lay it on with a trowel. Cap in hand goes through the land. Not go in and blurt out what you know you're not to: what's parallax? Show this gentleman the door.
His hand fell to his side again.
Never know anything about it. Waste of time. Gasballs spinning about, crossing each other, passing. Same old dingdong always.
An irony: Bloom thinks he doesn't know what parallax is, but in a way he does: he's aware that Dunsink time is 25 minutes different from Greenwich time, and that's parallax. The angle of the sun in relation to one object (London) is slightly different than its angle in relation to another object (Dublin). The Ballast Office clock is on Dunsink time, but the timeball atop it was synchronized to Greenwich time because Dublin is a port city, and in 1904 sailors -- whose lives were governed by Greenwich time -- were in and out of the city all the time. Two times indicated on one object: parallax.
But the fancy Greek term throws Bloom. He is a very intelligent and deeply curious but poorly educated man, and doesn't even know whom he should seek out to help him, or how he might solicit help. ("If I could get an introduction to professor Joly or learn up something about his family.") It's all too discouraging. His hand drops to his side and he gives up: "Never know anything about it. Waste of time."