This month's mystery engine comes, as usual, courtesy of John Spalding, 112 Carriage Place, Hendersonville, TN 37035 (firstname.lastname@example.org). There's no information on the photograph telling when or where the picture was taken, or what the engine is, but that hasn't stopped readers yet!
As ever, the first person to correctly identify the picture, by mail, gets a free copy of Professor P.F. Rose's Steam Engine Guide. Good hunting, and get those answers in quick.