How can I get the message?
Gail explains a cunning method for sending messages when your mobile phone is out of credit. Or if you were an ancient Greek, and inventing the mobile phone just felt like too much hassle.
It’s trivially simple now to send messages, but in 350BC they didn’t have mobile phones, AIM, nor even fax machines. Inventing all of that would be a bit of a step – so here’s what a chap called Aeneas came up with. The water telegraph.
The urn is full of water, on top of which floats…
Er… a float. Obviously. Sticking out of the float is a… well… it’s a stick.
On the stick, these markings – the letters of the Greek alphabet.
When the whole thing is put together, a collar around the stick makes it clear which of the markings are revealed and which are hidden.
For the system to work, you need two identical urns, and you need to be able to see the person operating the other one. It’s not crucial that the other person is Gareth, but if it has to be, it helps if he looks absolutely frozen. Well, it doesn’t help the telegraph work, but it gives you something to laugh at while it’s doing it’s thing.
Here’s how you send a message: first, you signal the other person that you’re about to send. Wave that flag, Gail!
The recipient signals that they’re ready to receive.
At the base of the urn, a tap. The sender opens it, and…
…waves their flag again to say they’re sending.
The receiver opens their tap too. There’s a bit of a lag here, but since the urns drain quite slowly, it’s not a big issue – and as you’ll see, it cancels out in a moment.
As the urns drain of water, the float lowers, hiding messages beneath the collar.
When the letter you want to send is just above the collar, you turn off the tap, and…
…signal the receiver, who turns theirs off too. The lag here should be about the same as it was at the start of the message, so the amount of water drained from both urns should be very nearly the same.
So the recipient now reads off the message. The only trouble is, it’s just one letter. Not exactly predictive text, is it?
Well, actually, yes. It is. Along with the urn comes a predefined list of all the messages you’re likely to send.
So your recipient reads off the message corresponding to the letter you sent.
…and lo, the tea and biscuits arrive. Good work, Gail.
Anyway, that’s how you can get the message, in 350BC.