The notion that the Romans used speaking tubes to communicate along the Wall can be traced back to at least Drayton in the 17th century and his poem called the Polyolbion where his personified Wall mentions
With hollow pipes of brasse, along me still they went
By which they in one fort still to another sent,
By speaking in the same, to tell them what to doe,
And soe from sea to sea could I be whispered through.
Although it was repeated by Camden, Collingwood Bruce rightly pooh-poohed the story and pointed out that no such brass pipes have ever been found, although noting that a similar tradition existed about the Antonine Wall.
Myth has a powerful place in the story of Hadrian’s Wall. The area of Sewingshields Crags has come to be associated with the tale of King Arthur lying asleep in a subterranean cave, waiting to be awakened to save England.
Further reading: Bruce 1853