|Capo tasto (Italian, from capo: head and tasto: tie, fret, key. French barre, German Capodaster). Originally this term denoted the nut of a fretted instrument such as the lute or guitar. The term was first employed by G. B. Doni in his Annotazioni of 1640. It is now generally used to describe a devise to shorten the string length, thus facilitating upward transposition without altered fingering.|
fretted instruments were introduced, man realised the use for a device that could fret all
the strings at the same time. The very first capo was
invented in the mid 1700's.
Both the yoke capo with screw and the wooden Spanish capo cejilla were invented in the late 1700's. The yoke capo still looks the same, and the Spanish capo is still in use by Flamenco guitarists. On the English guitar at that time, the capo was attached through holes in the neck by a small carriage bolt tightened by a wing nut. I have not found any patent on the C-clamp with screw, so I guess that capo is pretty old too.
The first capo patent was applied for in 1850 by James Ashborn of Walcottville, Connecticut. His capo was tightened by an eccentric roll on the back of the neck. Since then, about 130 capo patents have been granted (I'm writhing this 1999), but very few seem to be practical. My guess is that most of them never reached the market. (If you have the opportunity, I strongly recommend you to pay a visit to a Patent Office. You'll get many good laughs from watching the many crazy musical accessories man has invented.)
Perhaps the greatest capo invention was the elastic capo, patented by W. H. Russel in 1931. It is still going strong. Almost every capo user has had one.
The first plastic capo was invented by H. Bauerfeind in 1973.
In 1978 R.Shubb improved the C-clamp by adding a screw to a lever type capo, thus making the eccentricity adjustable.