The Capo: A Movable Nut You Clamp With One Hand

Ashborn notes that the use of the capo tasto "(the clamp used on the handle of a guitar to determine the vibrating length of the strings to set the instrument for playing in difficult keys), as heretofore made, is attended with great difficulty", so much so "that many performers have abandoned the use of it." The second part of his invention combines with the capo tasto, "or plate for pressing the strings onto any particular fret of the handle, a metal or other strap attached thereto and passing down on each side of the handle, and an eccentric roller journaled to the said strap and acting against the under surface of the handle, so that the said plate may, with one hand only, be drawn down onto the strings, and adjusted or liberated therefrom by simply turning the said roller", the whole being pushed back onto the head beyond the last fret, where it does not interfere with the strings. The first part winds the strings on spindles whose part below the head is enlarged — "from three to four times the diameter of the spindle on which the strings are wound" — driven by catgut from pegs of smaller diameter, "thereby increasing the leverage of the pins to overcome the tension of the strings" without the metal of a geared head.

Fit new strings to a cigar-box or acoustic guitar and tune it. Put the capo at the second, third and fifth frets in turn and measure each open string's pitch with a tuner app, checking the notebook's semitone steps. Loosen the capo until one string buzzes and note which: the thickest strings need the most force. Hook the spring scale under a single string just behind a fret and pull it down 1 mm to feel the force the capo supplies for all six.

**James Ashborn** of Walcottville, Connecticut, received US 7,279, dated 16 April 1850, for improvements in the guitar head and the capo tasto. **Honest limits.** String tensions and the pressing geometry in the notebook are examples; real capo force depends on the pad, the action and the string gauges.