The Secret of the Old Mill, Hardy Boys #3, by Franklin W. Dixon.  Book with brown cover, orange endpapers.  3 titles listed on copyright page.   212 pages plus lists - Hardy Boys, 12 titles; Don Sturdy; Tom Swift; Ted Scott; Western Stories for Boys; Aviation Series; Hal Keen Mystery.  Dust jacket with red shield on white spine has chips top front.  Hole on rear spine edge. Wear top of spine.   Front endflap lists Hardy Boys thru While Clock Ticked.  Rear of dust jacket Han Keen, 8 titles. Rear endflap, Western Stories (X Bar X) 11 titles.  Per Hardy Boys Bibliography - 1933A printing.