The Romans made organs which must have been simple from the musical standpoint, though they were complicated in their mechanical construction.  They were called hydraulic organs.  The employment of water in a wind instrument has greatly perplexed the commentators.  Cavaille-Coll studied the question and solved the problem by demonstrating that the water compressed the air.  This system was ingenious but imperfect, since it was applicable only to the most primitive instruments.  The keys, it seems, were very large, and were struck by blows of the fist.

Let us leave erudition for art and primitive for perfected instruments.  By the time of Sebastian Bach and Rameau the organ had taken on its grandiose character.  The stops had multiplied and the organist called them by means of registers which he drew out or pushed back at will.  In order to give greater resources, the builder multiplied the keyboards.  Pedals were introduced to help out the keyboards.  At that time Germany alone had pedals worthy of the name and worth while in playing an interesting bass part.  In France and elsewhere the rudimentary pedals were only used for certain fundamental notes or in prolonged tenutos.  No one outside of Germany could play Sebastian Bach’s compositions.

Playing on the old instruments was fatiguing and uncomfortable.  The touch was heavy and, when one used both the pedals and the keyboards, a real display of strength was necessary.  A similar display was necessary to draw out or push back the registers, some of which were beyond the player’s reach.  In short, an assistant was necessary, in fact several assistants in playing large organs like those at Harlem or Arnheim in Holland.  It was almost impossible to modify the combinations of stops.  All nuances, save the abrupt change from strong to soft and vice versa, were impossible.

It remained for Cavaille-Coll to change all this and open up new fields of usefulness for the organ.  He introduced in France keyboards worthy of the name, and he gave to the higher notes, through his invention of harmonic stops, a brilliancy they had lacked.  He invented wonderful combinations which allow the organist to change his combinations and to vary the tone, without the aid of an assistant and without leaving the keyboard.  Even before his day a scheme had been devised of enclosing certain stops in a box protected by shutters which a pedal opened and closed at will; this permitted the finest shadings.  By different processes the touch of the organ was made as delicate as that of the piano.

For some years the Swiss organ-makers have been inventing new facilities which make the organist a sort of magician.  The manifold resources of the marvellous instrument are at his command, obedient to his slightest wish.