As we still ascend from shelf to shelf, we find the tenants of the tower serially disposed in order of their magnitude: gannets, black and speckled haglets, jays, sea hens, sperm-whale birds, gulls of all varieties – thrones, princedoms, powers, dominating one above another in senatorial array; while, sprinkled over all, like an ever-repeated fly in a great piece of broidery, the stormy petrel or Mother Cary’s chicken sounds his continual challenge and alarm.