Strings and Pedals

This question refers to the modern concert harp.

Harps have been around since ancient times, and there are many different types – originating in all parts of the world. Needless to say, there was no standard number of strings, but according to Wikipedia it was the introduction of pedals (by Jakob Hochbrucker of Bavaria, in 1697) that turned the harp into an orchestral instrument. Even so, until the 19th century it was rarely used in classical music, and its use by Cesar Franck in his Symphony in D minor (1888) was described as "revolutionary".

Wikipedia gives several examples of the "pedal harp" being used outside classical music: for example, by Harpo Marx and in the Beatles song She's Leaving Home.