There are often several organs in old large churches: the large organ at the entrance on the west side, an organ (sometimes even two) by the choir on the east side, organs hidden in side chapels, and so on. The large organ at the west tower usually dominates. In Paris these large organs had the most allure. Here, greats such as Tournemire, Vierne and Dupré displayed their virtuosity. The choir
… organ near the altar obviously had an accompanying function. Some French composers made stereophonic use of the large organ opposite the choir organ in their masses. This is what happens here in the imposing Messe Solennelle op.16 by Louis Vierne. In the Kyrie of Mass the large organ provides the dramatic accents, while the small organ supports the choir. A similar role-play characterizes Jean Langlais's Messe Solennelle.more
