The question is how many points of articulation you need. Mirrors, while more expensive to make, would last longer than shutters.
They'd also only work in the daytime.
The question is how many points of articulation you need. Mirrors, while more expensive to make, would last longer than shutters.
Unless you put a lantern behind them. Requires more complexity for a proper signal but would work.They'd also only work in the daytime.
Unless you put a lantern behind them. Requires more complexity for a proper signal but would work.
Thinking about China, how would they encode the messages? Doesn't Written Chinese contain thousands of characters? With Roman numerals at least you only have to worry about 26 letters and 10 numbers, six shutters could represent 63 different characters, since 63 is 111111 in binary.
I think you'd have to adopt a code per character with the limit being the combination capabilities of the machine. If you did nine shutters you wouldn't be able to transmit a book or anything who's code hasn't been prearranged but with several hundred combinations possible you could certainly transmit fairly complex instructions. In fact, for simple messages it might actually be faster than an alphabet code since something like "send help quick" would be three characters rather than thirteen in English.
For government use that probably improves value but for commercial use I think it severely hinders its adoption.
But then we get back to the human error problem. How long will it take to teach an observer every character and then the code for that character, to the point where they could correctly identify every character almost every time? It's 40 characters against hundreds or thousands. And if every character is a word, then errors have a much bigger effect. 'sand hilp wuick' is still legible enough to notice errors and correct them. And if a preindustrial society is trying to build this system, there probably isn't a deluge of literate people willing to spend all day in a cold tower in the sky for what is likely very low wages. It only gets more difficult with a larger alphabet.
Note that this system doesn't have to be fast by our standards, it just needs to be a good deal faster than a galloping horse, about 45 kilometers per hour, or just under 30 mph.
Alternatively, postal train.
A single train could whip the arse of the entire semaphore network every day for ever.
Something like parity bits could be implemented which could improve reliability.I've had a bit of thinking, and it strikes me that if this network tries to send a message down a serious distance (London to Liverpool is about 180 miles, which could easily mean 20 or 30 towers in total), then there is a very large risk at human error distorting the message.
In bandwidth, yes.
In lag-time, no.
The clacks may be ten to twenty kilometers apart, and it may take as little as five minutes (ass-pull) to receive and transmit a short, priority message.
That's true enough. But that's the only advantage semaphore has - sending a single message over a very long distance, very quickly.
For all your other needs, postal trains can carry tens, if not hundreds of thousands of messages all at once. Not to mention parcels - you can't send that by semaphore...![]()
I'll point out that networkers don't necessarily need to understand the code being sent. You could potentially have the human form of a data packet, where the only things they really need to understand are the source, address, etc. and the remaining patterns are simply copied and carried over to the other tower, until it reaches the destination tower and the code is written down by a transcriber, who hands it to a decipherer, and the message is carried from there.
What were the prerequisite technologies
Not necessarily that complicated. The books make them into sort of proto-computers in their level of complication but doing an array of shuttered lights wouldn't require that much. You could do a series of weighted shutters with lights behind them at for night. It would be hell on the operator's arms but it's certainly doable with levers and a simple pulley system. Say a three man team in the tower at all times. One to watch left and send right, one to watch right and send left, and one to assist and perform maintenance like lubrication or light lamps.