Concord, New Hampshire. $20 1882 Brown Back. Fr. 504. The Mechanics NB. Charter #2447. PMG Very Fine 30.The boldly penned signatures of cashier Harry H. Dudley and president Benjamin A. Kimball are featured prominently on this evenly circulated and bright $20 Brown Back. This is one of just four $20 Brown Backs known on the bank. The Mechanicks National Bank was chartered in January of 1880 and had a total emission of $4,121,280 encompassing both large and small size notes. The design elements are all sharply printed and seen in great detail on this pleasing Second Charter period note.