I am currently working on a project at Stones River National Military Park in Tennessee. We have the opportunity to use an EM-38 electro-conductivity machine to look for subsurface features on the battlefield, earthworks, house sites, and cemetery. Does anyone have any suggestions as to what the best interval for testing is? Does anyone have any suggestions in general for using EM-38 for such projects? Success stories? Failures? Thanks, Margo Schwadron