The knock on the eastern boundary of the parish [of Alves] is crowned by a tower, from which an extensive view of the surrounding country and of Ross and Sutherland across the Moray Firth can be commanded. By tradition the knock is connected with the story of Macbeth and the witches. Possibly there may be some foundation for this, as the knock is on the road between Bothgownan and the Blasted Heath, the one by a curious coincidence being about three miles east of Elgin, and the other a similar distance from Nairn.
From ‘The Place Names of Elginshire’ by Donald Matheson (1905). (Foundation??)