Drums are the most effecient long-distance communication on Pern after Dragons. A network of drumtowers cross the Northern Continent. Messages can be relayed by a special code from one tower to another, carrying messages across the Continent at the speed of sound (or actually a little lower, due to the necessary delay at relaying stations). This system was first devised during the First Pass when the old technological solutions, such as telegraphs, proved impractical due to Thread and the resources required to fight it. The original drum tower at the College (later Harper Hall) was constructed during the year 1P48 (56 AL) The system continued in use into the Ninth Pass. With Fandarel's reinvention of the telegraph, and especially the rediscovery of ancient science thanks to the AIVAS, it appears to be on its way out now.