Improvements In Guitars
US patent 1873 by Rudolph Knaffl of Nashville, Tennessee.
| The roller capo is pulled down the instrument neck by means of a treadle P, rods J K and cords L M. The India-rubber roller D is made self-retracting upon the fret-board by means of the India-rubber spring V. The lower extremity q of the staff Q is pointed to prevent its slipping upon the floor. |