Oh Whistle and I'll Come to You, My Lad

In the story, a young, scientifically-minded college professor finds an old bronze whistle while exploring the ruins of a Knights Templars' preceptory. That night, he blows on the whistle and a vision comes to him of a dark expanse with a lonely figure in its midst. The sound also appears to call up a gust of wind, but the sensible professor dismisses it as a coincidence. More strange incidents follow, however, to shake his disbelief in the supernatural.