Earliest Telegraph

[maidros]

The technology for electrical telegraphs existed in the Persian empire itself - all you need is to move a magnet in a coil of wire (both of which, in their crude forms, were available in the Persian empire itself) to generate a current. It is just the fact that no one realised that this was a means of communication. If someone realised this fact, could we have electrical telegraph in the Roman empire/Persian Empire/Mauryan Empire/Han Empire? What other constraints existed to make this infeasible?

Off hand, I can think of two problems.

1) There is not enough high quality conductor (copper wire enough to span the length and breadth of Europe is not exactly easy to obtain).

2) Protecting the conductor from the elements is also a problem. There are no easily available insulators there.

Could the problems be overcome? Do let me know your ideas.

 

[DStecks]

Magnetism wasn't properly understood before the middle ages, even in China. Electromagnetism wasn't conceived of before 1873. All of the components may have existed, but somebody actually putting all these ideas together would be analogous to somebody in 2013 building an Alcubierre drive.

 

[Dathi THorfinnsson]

Magnetism wasn't properly understood before the middle ages, even in China. Electromagnetism wasn't conceived of before 1873. All of the components may have existed, but somebody actually putting all these ideas together would be analogous to somebody in 2013 building an Alcubierre drive.

Exactly. Could you get batteries? Sure. But how do you tell whether theres a current in the line? That pretty much requires an understanding of electromagnetism.

 

[maidros]

Magnetism wasn't properly understood before the middle ages, even in China. Electromagnetism wasn't conceived of before 1873. All of the components may have existed, but somebody actually putting all these ideas together would be analogous to somebody in 2013 building an Alcubierre drive.

You have it backwards. We know the theory of Alcubierre drives - we just don't know how to expand and contract distance with the energy we have at our disposal.

On the other hand, all that is needed is a fortunate accident of a lodestone in a spinning coil of wire to get a current. You don't need to understand magnetism or Maxwell's equations to get a current in a wire.

Indeed, as a matter of fact, electricity in a coil was recognised nearly two centuries before electromagnetism was understood.

 

[maidros]

Exactly. Could you get batteries? Sure. But how do you tell whether theres a current in the line? That pretty much requires an understanding of electromagnetism.

Again, neither batteries, nor recognition of current are needed. An experiment was performed by French monks led by Jean Antoine Nollet, in which he exhibited that the transmission of electricity in a conductor was instantaneous (for small distances) using nothing more complicated than iron wires connecting the monks and a Leyden Jar to generate the current. it is not necessary to understand the phenomenon to reproduce it.

 

[PoorBoy]

Who needs electricity? The French Revolutionary Governments pretty much had a semaphore system set up by the late 1790s.

All you need are towers, and a clear line of sight between the towers. In fact, the earliest electrical telegraphs were criticized at first in that one could easily sabotage the system by literally cutting the lines.

A Roman telegraph system? Chinese system? Persian system? Egyptian system? I'm more surprised at why no one though of this much earlier.

 

[Elfwine]

Again, neither batteries, nor recognition of current are needed. An experiment was performed by French monks led by Jean Antoine Nollet, in which he exhibited that the transmission of electricity in a conductor was instantaneous (for small distances) using nothing more complicated than iron wires connecting the monks and a Leyden Jar to generate the current. it is not necessary to understand the phenomenon to reproduce it.

Except that if you don't understand the phenomenon - at least crudely - duplicating it will be difficult, because you don't know what you need to do in order to do duplicate it.

Doesn't mean you need a full understanding of the theory - just what you need in order to practically do X.

It's all well and good to have an exhibit in prepared conditions, but it might not be enough to establish a system.