I came across this photograph with a dulcimer player on the box and fiddle archive. boxandfiddlearchive.weebly.com/coalburn-chronicles.html The caption underneath lists the players, "The Douglas Water Dance Band in the 1940’s (1) Peter Burrell (melodeon) (2) Bobby Kennedy (dulcimer) (3) Jimmy Hynds (drummer) (4) Jim Simpson (piano accordion)"
I did notice they looked quite long. I've had another look on the website and they do look straight right enough. Strange! Have you seen the photograph on Paul Giffords website,www.giffordmusic.net/Ethnic%20Dulcimer.html taken in Glasgow around 1920?