The next step would be to combine a set of flutes or shepherd's pipes with the wind reservoir of the bagpipes, placing a little slider under the mouthpiece of each pipe which could be opened or closed at will, so that they would not all speak at once. Then some genius steadied the wind pressure by pumping air into a reservoir partly filled with water. This was the so-called "hydraulic organ," which name has given rise to the impression that the pipes were played by the water passing through them--which is impossible. And so we come down the ages to the Christian era. The Talmud mentions an organ (magrepha) having ten pipes played by a keyboard as being in existence in the Second Century. "Aldhelm (who died A. D. 709) mentions an organ which had gilt pipes. An organ having leaden pipes was placed in the Church of S. Corneille, at Compiegne, in the middle of the Eighth Century." St. Dunstan had an organ with pipes made of brass. Then we have the organ in Winchester Cathedral, England, described by Wulfstan of Winchester in his "Life of Saint Swithin." This was a double organ, requiring two organists to play it. It contained 400 pipes and had thirteen pairs of bellows. It was intended to be heard all over Winchester in honor of St. Peter, to whom the Cathedral was dedicated. The year was now A. D. 951, and this is an important date to remember, as modern harmony took its rise about this time. Before this, as far as we know, there had been no harmony beyond a drone bass, and the vast companies of musicians described in Holy Writ and elsewhere must have played and sung in octaves and unison. I quote Stainer again: "The large pipes of every key of the oldest organs stood in front; the whole instrument sounded and shrieked in a harsh and loud manner. The keyboard had eleven, twelve, even thirteen keys in diatonic succession without semitones. It was impossible to get anything else than a choral melody for one voice only on such an organ * * * the breadth of a keyboard containing nine keys extended to three-quarters the length of a yard, that of the single key amounted to three inches * * * even from five to six inches * * * The valves of the keys and the whole mechanism being clumsy, playing with the finger was not to be thought of, but the keys were obliged to be struck with the clenched fist, and the organist was often called '_pulsator organum_' (organ beater)." Gradually the keys were reduced in size and the semitones were added. By 1499 they had almost reached the present normal proportions. In 1470 pedals were invented by Bernard, the German, a skilful musician of Venice, the pipe work was improved and so we come to the Sixteenth Century[1] after which the organ remained almost _in statu quo_ for hundreds of years. Since then there have been four great landmarks in organ construction, viz: 1. The invention of the swell box by Jordan in 1713; 2. The invention of the horizontal bellows, by Samuel Green, in 1789;