[Illustration: FIG. 33.――ORGAN. From a 12th century psalter in the Library of Trinity College, Cambridge.] The _pneumatic organ_ is sculptured on the base of an obelisk which was erected in Constantinople under Theodosius the Great towards the end of the fourth century. The bellows were pressed by men standing on them. This interesting monument also exhibits performers on the double flute. The _hydraulic organ_, which is recorded to have been already known about two hundred years before the Christian era, was according to some statements occasionally employed in churches during the earlier centuries of the Middle Ages. Probably it was more frequently heard in secular entertainments, for which it was more suitable; and at the beginning of the fourteenth century it appears to have been entirely supplanted by the pneumatic organ. The earliest organs had only about a dozen pipes. The largest, which were made about nine hundred years ago, had only three octaves, in which the chromatic intervals did not occur. Some progress in the construction of the organ is shewn in a psalter of Eadwine, in the library of Trinity College, Cambridge (Fig. 33). The instrument has ten pipes, or perhaps fourteen, as four of them appear to be double pipes. It required four men exerting all their power to produce the necessary wind, and two men to play the instrument. Moreover, both players seem also to be busily engaged in directing the blowers about the proper supply of wind. Six men and only fourteen pipes! Another illustration is given of an organ of the 14th century (Fig. 34). [Illustration: FIG. 34.――ORGAN (Grand Orgue), after an engraving in N. X. Willemin’s _Monuments Français Inédits_, Vol. I., pl. 133, taken from a psalter of the 14th century.] The pedal is generally believed to have been invented by Bernhard, a German, who lived in Venice about the year 1470. There are, however, indications extant pointing to an earlier date of its invention. Perhaps Bernhard was the first who, by adopting a more practicable construction, made the pedal more generally known. On the earliest organs the keys of the finger-board were of enormous size, compared with those of the present day; so that a finger-board with only nine keys had a breadth of from four to five feet. The organist struck the keys down with his fist, as is done in playing the _carillon_ still in use on the Continent, of which presently some account will be given.