t and foremost of which was the
Barker pneumatic lever (see _ante_, page 120). The wind pressure was
on a new system, whereby increased pressure was applied to the upper
notes, giving more regularity of tone to each stop. The wind
reservoirs were provided with double valves, insuring a more steady
supply, whether all the stops were played together or separately. The
introduction of Harmonic stops was practically an innovation, as their
use hitherto had been almost prohibited by the difficulty of playing on
a high wind pressure (see _ante_, page 21). This enriched the organ
with a new group of stops of a superior quality on account of the
roundness and volume of sound.

In 1840 Cavaille-Coll submitted to the Academie des Sciences the result
of his experimental studies of organ pipes; on the normal tone of the
organ and its architecture; the length of pipes in regard to intonation
and precision in blowing. He made many experiments and improvements in
wind supply. He was also the inventor of "Poikilorgue," an expressive
organ, which was the origin of the harmonium.

Between 1834 and 1898 he built upward of 700 organs, including Saint
Sulpice, Notre Dame, Saint Clotilde, la Madeleine, le Trocadero, Saint
Augustin, Saint Vincent de Paul, la Trinite (all in Paris); Saint Ouen
at Rouen, Saint Sernin at Toulouse; the Cathedrals at Nancy, Amsterdam,
and Moscow; the Town Halls of Sheffield and Manchester, England. The
most celebrated of these is Saint Sulpice, which contains 118 stops and
was opened in April 29, 1862.[1]

The fine period of Cavaille-Coll was during the Empire, about 1850.
The Emperor Napoleon III, to flatter the clergy and the bishops,
ordered the Cathedral organs to be rebuilt, and gave the order to
Cavaille-Coll. He in many instances preserved the old soundboards,
dividing them on two ventils for reeds and for flues, increased the
wind pressures, introduced pneumatic levers, and transformed the small
Tenor C Swells into large 15 to 20 stop Swells, _with 16-foot reeds_
included, and so crowned the fine flue work and mixture work of these
Cathedral organs.

We all know the fine effect of a large Swell. The French Cathedral
organs were deprived of this tonal resonance in 1850, and
Cavaille-Coll, by judicious overhauling, use of good materials, and by
the addition of large Swells, _transformed the sonority of these large
instruments located in splendid positions_ above the grand west
entrance doors of