The organ is an enormous instrument by Cavaillé-Coll. It possesses 118 stops, 5 manuals, 20 composition pedals, and some 7,000 pipes. Exquisitely played by M. Widor, one is carried away from the unsympathetic surroundings, particularly when the Seminarists form in procession and pour out the solemn old Gregorian tones, the beauty of which no one can understand unless they have been heard by a mass of men's voices and accompanied by an organist who understands harmonizing with taste. The organ here, as at all the Paris churches, is at the west end of the nave, and is only used for voluntaries and solo performances, never to accompany voices, for which purpose a small instrument is always placed close to the choir, either at the side or behind the altar. This is a much better arrangement than our modern one of having a huge organ in the chancel thundering away and drowning the voices. Of course it necessitates two organists, but the gain in refinement is worth the outlay; and there is no reason why the choirmaster, who would accompany the singers, should necessarily be a first-rate player. Although there are no remains of an earlier building, there was a parish church upon the same site as S. Sulpice as early as the 12th century; this was enlarged under Louis XII. and François Ier. [Illustration: SAINT-SULPICE FROM THE LUXEMBOURG GARDEN.] A brass slab incrusted in the pavement of the south transept indicates the meridian in a direct line towards the north--an obelisk. When the weather is fine, the midday sun shines through a little opening in the window of the south transept, and strikes the middle of the _plaque_ in Summer, and the top of the obelisk in the Winter solstice. This meridian was established in 1743 by Henri Sully and Lemonnier, to fix the Spring equinox and Easter Day. SAINT-THOMAS D'AQUIN.