The harp was not so often seen as other instruments, on account both of the great cost of the instrument and of the difficulty of tuning it. It was not until 1720 that the pedal harp was invented by a Bavarian named Hochbrücker. By means of the pedal working a small plate set with projecting pins, the performer was able to raise the pitch of each string a semitone. The mechanism was concealed in the front pillar, and each note was affected in all its octaves. Erard made farther improvements. The harp shown in Figure 88 is in the Metropolitan Museum, New York. It is a very handsome one, painted blue, and resting on four claw feet. The pillar is fluted, and the ornaments, three medallions of dancing girls, with wreaths below, are executed in brass. It has forty-two strings of gut and seven pedals. It was made by Naderman, Paris, France, late in the eighteenth century. Naderman perfected the action of the first pedal harp invented by Hochbrücker. In the South Kensington Museum, London, England, is a harp which belonged to the ill-fated Marie Antoinette; it also was made by Naderman in 1780. [Illustration: Figure 90. GLASS HARMONICA.] The harp in its various forms is an instrument of great antiquity. The Greeks and Romans, ever alive to the possibilities of everything that tended to grace and beauty, admired this instrument not only for its sweet sound but for its pleasing form. We must look to Egypt for the origin of the harp, as there are representations in their picture writings of stringed instruments of a bow-form that support the idea that the first conception of a harp was drawn from the tense string of a warrior's bow. This very primitive instrument was borne on the performer's shoulder and played horizontally. Between this crude instrument and the splendid vertical harps shown in the frescoes of the time of Rameses III., painted more than three thousand years ago, there is a chain of pictures showing so many varieties of forms that the growth from the bow-form into the triangular harp is explained. The Assyrians, like the Egyptians, had harps without a front pillar, but differing from them in using sound-holes, and having the sound body uppermost. We assign to King David the harp, but mediæval artists more frequently depicted him with the psaltery, a horizontal stringed instrument, the parent of the piano.