The Opera-house referred to in the extract above quoted, is the Academie Nationals de Musique, or French Opera-house, also sometimes called the new Opera-house.  It is generally admitted to be the finest Opera-house in the world.  The space covered by this magnificent building is 140 metres by 122, (about 470 feet by 410), or nearly four and a half acres.  It has seats for 2,520 spectators.  The staircases, walls and ceiling are of the finest marble.  The “house” for the spectators or audience is built entirely of stone and iron, rich in decorations and thick with gold.  The stage alone is a quarter of an acre in extent, being 128 feet wide by 85 feet long.  Below the stage there is a depth of 47 feet, from which the scenes are drawn up all in one piece.  This abyss below the stage was obtained at an immense cost, as the architect had to lay the foundations far below a subterranean body of water, but the advantage thus gained enables them to present scenes that are marvelous.  “The singers in this opera are pupils of the Conservatoire, and the corps de ballet consists of the most distinguished dancers of the day.  Great attention is paid to costume and general effect.”  During the matchless performances of a night that I was present, there were at one time nine large horses and a procession of several hundred actors upon the stage, and it was far from being full.  One of the most beautiful and astounding performances of the night was the production of a series of transformations that were as sudden and as astonishing in their developments as is the metamorphosis of the gaudy butterfly from the groveling worm.  As the curtain rose there stood upon the stage a mighty fortress, massive and strong.  We had seen it but long enough to observe how thick and how rough from age its weather-beaten walls were, when there was heard a crash, and the mighty citadel had fallen out of sight; but there still remained a most beautiful castle which must have been contained inside of the citadel but hid from the view by its towering walls.  This castle was beautiful beyond description.  It was fairer far than the castles of the kings seem to be, except when “distance lends enchantment to their view.”  But the second scene was as ephemeral as the first.  We beheld its fascinating beauties only a few seconds when its four walls again dropped into the abyss below, and there issued from its inner apartment a host of beautiful little actresses such as I did not see upon any other stage in Europe.  These little fairy-like beauties, many perhaps not more than from 5 to 10 years of age, all dressed in the most brilliant costumes, at once skipped into a dance “running the ring and tracing the mazy round,” to the great satisfaction of the admiring spectators, who were as much delighted by the gayety, grace and accomplishment which they displayed in their performances, as they have been astonished at their sudden and almost miraculous appearance.

At a Ball.