Discworld question, re: clacks towers.

In “Going Postal” It is mentioned that the older clacks towers need line of sight to work.

Bearing in mind that most of the ‘technology’ in discworld is based on real world technology at least a hundred years old, how is this achieved?
And which book (if any) is mostly about the introduction of clacks towers? (I’ve noticed that often the books are about the establishment of a service. The truth was about the introdcution of a Newspaper to Ankh-Morpork. Going Postal is obviously about the re-introduction of the postal service)

Not sure what you mean… they’ve just built a butt-load of towers across the continent, each one just within visual range of the next. Dunno if they use telescopes to cross the less settled areas or what. It would make sense, but I don’t recall any specific mention of their use in a clacks tower. Technologically, there’s nothing at all fancy here: it’s considerably less sophisticated than the telegraph, although conversely much more complicated. Training up enough cryptologists to man all those thousands and thousands of clacks towers must be a tremendous bottleneck, not to mention building and provisioning the towers themselves. Far more expensive than a wooden pole and some copper wire with an operator at each end.

There isn’t a book that focuses on the invention/introduction of the clacks towers, unless you count Going Postal. It’s just sort of grown up in the background of a bunch of other novels.

IIRC, the clacks just sort of developed in the background of several stories. The Fifth Elephant uses them as a plot device, and they were starting to get installed as far back as Jingo.

The clacks were introduced in The Fifth Elephant. That book wasn’t about the clacks though.

I’ve been wondering about the technology, too. Maybe I should re-read The Fifth Elephant, I don’t remember if it was explained there.

In Jingo there was a scene aboard the Boat in which Leonard is mentioning the notion of color as language, such as in semaphore and Vetinari makes some notes about it.

I’ve always suspected that Vetinari let the idea leak to somebody (not Dibble, of course) who saw the business opportunity in long range communication and thus the clacks tower was born.

For Miller and others. By line of sight, I mean there is a direct path between towers for light to travel. Maybe I mis-read the passage but it implied that new towers work even if there is something in the way between towers.

Most mundane thread correction of the year: I meant to bold Miller’s name, not italic it.

Lobsang, could you find the passage in question? Remember

the key plot point at the end of the book involves line-of-sight transmission.

I should add that I am about halfway through the book.
I have no idea which part of the half I’ve read the passage is in. I will look through it when I get the free time to do so.

Lobsang, I recall that there was a subplot about John Dearheart having invented a new clacks system that was more efficient than the old one, but I don’t recall anything about it not needing line-of-sight. If there was something about that, it wasn’t explained in any more detail than you’ve already read, nor does it materially impact the plot of the novel. All the clacks towers featured in the novel use line-of-sight to communicate between cities.

If I had to guess, I’d assume he’d invented a proper telegraph. It doesn’t really require any technology that the Disc doesn’t already have, or couldn’t reasonably invent from what they already know.

I’m not all the way through the book, yet, but I think somewhere there is a mention of

Unmanned towers that can bounce a signal, maybe using a mirror of some sort. The implication seemed to be that you could bend the signal around an obstacle that way, without setting up a complete clacks tower.

Ah, Mirrors! How could I have been so stupid?!

Haven’t read Going Postal yet, but how would a system with imps work?

Also the original clacks couldn’t work at night - the newer ones have lights.

Actually, in Monstrous Regiment there are some references as to how it all works, including mechanical logarithms, or some such, shich my knowledge of math doesn’t cover.

Being that I’m too cheap to buy hardcover, I’m always a little behind in Discworld novels. In fact, I’m on just finishing up Monstrous Regiment.

One of the characters, Lt. Blouse, starts talking about theories he has as to improve the efficiency of the clacks. Of course, since his religion finds them an abomination, he never had practicle experience.

Maybe after that book, he was allowed to put some of his ideas to the test.

BTW: there was a sophisticated pre-telegraph system of sephamores in place in France as far back as the Revolutionary period.

I haven’t read Monstrous Regiment, so Pterry may have said something that contradicts this, but…

I had always thought that the clacks were based on the semaphore telegraph towers that had stretched from the Admiralty in London to the dockyards in Portsmouth.

http://www.wordiq.com/definition/Semaphore_(communication) has some history of the semaphore towers.

They started as semaphore towers, but they have evolved. Now, they use a grid of lights to send coded signals from one tower to the next.