With the universal spread of the Christian faith the organ found its way into the service of the Church, and even during the decline of the empire and the dawn of western civilization the art of organ-building never altogether died out. And this, despite the fact that originally the instrument had come under the ban of the Church because of its heritage of evil associations with the gladiatorial combats, saturnalia and theatrical representations of Pagan Rome; possibly, also, because the emperor Julian the Apostate was the owner of a fine _hydraulus_. Yet this prejudice was ere long overcome, for the Spanish bishop, Julianus, in the fifth century, asserts that organs were commonly used in the churches throughout Spain. And such is the esteem in which the finer examples of the builder’s art are held that they are considered a gift fit for kings. The Emperor Konstantine Kopronymus presents one to Pepin, king of the Franks, in the year 757; and another Byzantine emperor sends one to Charlemagne in 812, of which the chronicle says: ‘Its bellows were of hide, its pipes of bronze, its tones as loud as thunder and sweet as the sound of lyre and psaltery.’ A pneumatic organ (as distinct from the hydraulic one installed in his palace) was secured by the son of Charlemagne, Louis le Debonnaire, for the royal chapel at Aix-la-Chapelle. And before the tenth century the use of the organ in church and monastery was well-nigh universal. Three treatises on organ-building written during the tenth century testify to the fact. No doubt these early hydraulic instruments had stops of some kind, but if so, their secret has perished with them. The tenth century (as well as the eleventh) was one of great activity in organ-building. Numerous small organs were made in France, England and Germany for use in cloister schools, where they supported the singing of the Gregorian melodies. They usually consisted of a series of from eight to, at the most, twenty-two pipes, tuned in the scale of C major, from the tenor C upward. The pipes resembled the modern diapasons in construction and stood behind a species of manual with small keys (upright at first, but later horizontal) which allowed the wind to enter the pipes when they were pressed down. Into these organs the wind was pumped by bellows and water-power was not used to regulate the pressure.