WikiTrade

Optical telegraph

An optical telegraph is a line of stations, typically towers, for the purpose of conveying textual information by means of visual signals. There are two main types of such systems: the semaphore telegraph which uses pivoted indicator arms and conveys information according to the direction the indicators point, and the shutter telegraph which uses panels that can be rotated to block or pass the light from the sky behind to convey information.

On WikiTrade, every Wikipedia article is a card: the more the article is read, the rarer the card. Open free packs, complete your album, trade, bid and challenge others to general-knowledge duels.

Text from Wikipedia (CC BY-SA 4.0). WikiTrade is an independent site, not affiliated with Wikipedia or the Wikimedia Foundation.