Autograph letter signed by John B. McDonald, chief engineer and builder of the New York subway system. Letter, dated 8 August 1904 on Rapid Transit Subway Construction Company letterhead, reads in full: ''Dear Sir: - I acknowledge receipt of your letter of August 5th, enclosing ticket for admission to the Sagamore, for which please accept thanks. Your very truly, John B. McDonald''. Sagamore is Washburn University's prestigious honor society for men. Single page measures 8.5'' x 5.5''. Expected mailing folds and light ink transfer from being stacked with other letters, else fine.