Those are sights which few have been privileged to see. There is a sort of centralization of mystery, if one may couple such words, in the private pilgrimage of the head of the Church to the tomb of the chief Apostle by night, on the eve of the day which tradition has kept from the earliest times as the anniversary of Saint Peter's martyrdom. The whole Catholic world, if it might, would follow Leo the Thirteenth down those marble steps, and two hundred million voices would repeat the prayer he says alone. Many and solemn scenes have been acted out by night in the vast gloom of the enormous church, and if events do not actually leave an essence of themselves in places, as some have believed, yet the knowledge that they have happened where we stand and recall them has a mysterious power to thrill the heart. Opposite the Chapel of the Sacrament is the Chapel of the Choir. Saint Peter's is a cathedral, and is managed by a chapter of Canons, each of whom has his seat in the choir, and his vote in the disposal of the cathedral's income, which is considerable. The chapter maintains the Choir of Saint Peter's, a body of musicians quite independent of the so-called 'Pope's Choir,' which is properly termed the 'Choir of the Sixtine Chapel,' and which is paid by the Pope. There are some radical differences between the two. By a very ancient and inviolable regulation, the so-called 'musico,' or artificial soprano, is never allowed to sing in the Chapel of the Choir, where the soprano singers are without exception men who sing in falsetto, though they speak in a deep voice. On great occasions the Choir of the Sixtine joins in the music in the body of the church, but never in the Chapel, and always behind a lattice. Secondly, no musical instruments are ever used in the Sixtine. In the Chapel of the Choir, on the contrary, there are two large organs. The one on the west side is employed on all ordinary occasions; it is over two hundred years old, and is tuned about two tones below the modern pitch. It is so worn out that an organ-builder is in attendance during every service, to make repairs at a moment's notice. The bellows leak, the stops stick, some notes have a chronic tendency to cipher, and the pedal trackers unhook themselves unexpectedly. But the Canons would certainly not think of building a new organ.