A curious development of the _rococo_ spirit of the age was the amount of money spent on the tasteless external embellishment of the instrument--angels posturing on the organ-cases, who by means of a mechanism beat kettle-drums and cymbals and blew trumpets, and ‘cymbal stars’ which jingled as they revolved on wires. Yet such errors in judgment represented no more than a temporary aberration of taste, and the century as a whole is one of continual mechanical progress with corresponding musical results. It is in the nineteenth century, however, that the great advance in the mechanics of organ-building, which has culminated in the present perfected instrument of to-day, begins. Cavaillé-Col (b. 1811) introduced separate wind-chests, with varying pressures for the higher, middle and lower parts of the keyboard, and added _flutes octaviantes_ to the register. In 1832 C. S. Barker (England) invented composition pedals, making easier the handling of groups of stops, and the pneumatic lever. And, finally, with the improvements of H. W. Willis and the electro-pneumatic action of Péschard (1866) (electricity had already been applied to the key-action by Dr. Gauntlett in 1850), the history of the ancient organ comes to an end and that of the modern instrument begins. F. H. M. V The processes by which the organ has developed from its clumsy prototypes to the magnificent yet sensitive and delicate instrument of to-day are parallel to those to be found in other products of man’s ingenuity. Practical science has contributed step by step to this evolution, and no one can understand the modern organ who is not familiar with the latest inventions of electro-pneumatics. The first step was the introduction of pneumatic mechanism to open the pallets in the old open slide chests, thus equalizing the touch of the key-action. This also made it possible to greatly increase the number of stops served by a single pallet. The next problem was to avoid increasing the weight of the key-touch when the couplers were drawn, and this was accomplished by an extension of the pneumatic system in the key-desk, which in this case was connected by action-tubing to the chests. The resulting combination of an entirely pneumatic key-action with the pneumatic operation of the pallets constituted tubular pneumatic action.