Up
to the sixteenth century, all harps were diatonic and could not produce
sharps and flats.
-
unless the player pressed a thumbnail against a string to raise
its note a semitone
They
were excellent musical instruments as long the music kept to one key,
as was the case for most folk and popular music.
As
the harp became required for more sophisticated kinds of music for
which semitones were necessary, the harp makers of the sixteenth century
made harps with a second row of strings alongside the original row;
this second row of strings provided the sharps and flats.
- or the two sets could pass through one another, with an 'x'
cross-section, as in the Italian double harp, 'arpa doppia': illustration
here.
A better
solution was found in Wales, which consisted of sandwiching a row
of semitone strings between two outer rows with the normal scale in
duplicate. But the Welsh "triple harp" was too difficult
to play and it was replaced by the double-action pedal harp invented
by a Frenchman, Sebastian Erard, driven from France to Great Britain
by the French Revolution. His invention was patented in London in
1792, but the complicated mechanism of the Erard harp is beyond the
scope of the amateur harp maker.
The
simpler system of hooks invented in the Austrian Tyrol towards the
end of the seventeenth century is still used on Folk harps today.
At first, not every string was given the advantage of a hook, but
now the Minstrel and Celtic harps have hooks on all strings.
The
Paraguayan harp, however, had remained diatonic, but there is no reason
why it should not be modernised. The trouble is that it is a perpendicular
harp, and thus cannot receive hooks in the normal way.
