cavaillé-coll grouped the stops of the organ into different families, so that the result was similar to the families of instruments in an orchestra. he made the lowest of the manuals (keyboards) the most important one. it was called the “great” (french: “grande orgue”). the other manuals - there were usually two others, but sometimes three - could be “coupled” to the great. he made changes to the english swell box, improved its operation, and divided the windchests on which the pipes were resting. this made it possible to have louder reed stops because of the higher wind pressure.