The Appalachian Mountain Dulcimer has hardly been studied at all, and very little is known about its detailed acoustics or the way it makes sound. In 2008 I started a series of experiments in an attempt to better understand the vibratory and acoustical behaviour of the mountain dulcimer. Experiment results were posted on the EverythingDulcimer.com website so that mountain dulcimer makers could take from it what they found relevant to their constructional methods, and to broaden the general understanding of the acoustics of the instrument. The EverythingDulcimer website closed in 2018, and to prevent the experimental information from being lost, Jon Leachtenauer, a U.S. dulcimer maker from Charlottesville, Virginia, collected and collated the forum posts and compiled them into a PDF-format book. The book has over 400 pages and over 300 illustrations. It is not a “how-to-make-a-mountain-dulcimer” manual, but rather the results of a series of practical experiments that shed some light on particular aspects of the acoustical workings of the mountain dulcimer. Dulcimer makers, and those attracted to the technical aspects of musical instruments may be interested. A low resolution version of the book is free to download, and for those who would like higher resolution in the pictures and graphs, an eBay search for “An Interesting Dulcimer Experiment” should return purchase details of the book in DVD format. The cost is USD$20, which includes postage. Alternatively, I can be contacted through this website.