Longitude

Sir Edmund Halley: Don't touch that, boy!

William Harrison: I didn't, sir, honest, I was just looking.

Sir Edmund Halley: Do you know what that is?

William Harrison: To tell the movements of the stars.

Sir Edmund Halley: How do you know that?

William Harrison: It's my job at home.

Sir Edmund Halley: You have one of these at home!?

William Harrison: No, sir, we use Mr. Johnson next door's chimney.

Sir Edmund Halley: And, pray, what is it that you learn from Mr. Johnson next door's chimney?

William Harrison: The time.

Sir Edmund Halley: How can you tell the time with a chimney?

William Harrison: If you stand in the right place, you can see Sirius.

Sir Edmund Halley: Sirius?

William Harrison: It moves behind Mr. Johnso's chimney 3 minutes and 56 seconds earlier every day. We need the time for our timepiece, to tell if it's true.

Sir Edmund Halley: And is it?

William Harrison: It's bloody perfect, sir.