Signal Mirror

The housing contains three mirrors that fold together for compact storage. The front cover, containing the mask and shutter, flips down; the back cover flips up and releases the two aiming mirrors. The entire mechanism is mounted in concentric stability rings to keep the mirror pointed in a single direction regardless of the motion of the ship.  

Operation

The mirror is aimed with the shutter nearly closed, letting light pass only through a small hole in the center of the reflecting mirror. The lookout adjusts the angle of the aiming mirrors until she sees the target at the center of the crossed lines on the second mirror. She spins up the stability rings, and when the aim is true she releases the locking pin. The shutter operates by a pneumatic cable, opening and closing at specific intervals to create the message.

At the same time that solar ovens began to replace boat hearths, small mirrors were first used to flash signals between mother ships. The earliest versions were as simple as possible, a single piece of glass waved by hand at a ship to get the crew's attention for a flag message to follow. As use of the mirrors became more widespread, Tideriders developed signal codes to substitute for the most commonly used flags: affirmative, negative, help, danger, and meet.   The code expanded over time to the point that any message could be conveyed by mirror. The sheer complexity of the system led to a higher rate of mistakes, and of course a mirror can't be used at night or on a cloudy day, but despite these drawbacks the mirrors remain in use. The discovery of air waves 600 years ago filled in those gaps, but did not replace the signal mirror entirely.

Signal mirrors are the middle range of the three remote communication systems Tideriders use most today. Flags are still used to communicate between boats within a single fleet, and air-wave communication is preferred for cloudy days and complicated messages, but the signal mirror is still quickest and easiest to use when the sun is shining and the target ship is far off but within sight.