The mere comparison of numbers of pipes and of stops, or of external dimensions, though it gives an approximative idea of the scale of an organ, is not so decisive as it might seem as to its real musical effectiveness. In some cases, many of the stops are rather nominal than of any real significance. Even in the Haarlem organ, which has only about two-thirds as many as the Boston one, Dr. Burney says, "The variety they afford is by no means what might be expected." It is obviously easy to multiply the small pipes to almost any extent. The dimensions of an organ, in its external aspect, must depend a good deal on the height of the edifice in which it is contained. Thus, the vaulted roof of the Cathedral of Ulm permitted the builder of our Music-Hall organ to pile the _facade_ of the one he constructed for that edifice up to the giddy elevation of almost a hundred feet, while the famous instrument in the Town Hall of Birmingham has only three-quarters of the height of our own, which is sixty feet. It is obvious also that the effective power of an organ does not depend merely on its size, but that the perfection of all its parts will have quite as much to do with it. In judging a vocalist, we can form but a very poor guess of the compass, force, quality of the voice, from a mere inspection of the throat and chest. In the case of the organ, however, we have the advantage of being able to minutely inspect every throat and larynx, to walk into the interior of the working mechanism, and to see the adaptation of each part to its office. In absolute power and compass the Music-Hall organ ranks among the three or four mightiest instruments ever built. In the perfection of all its parts, and in its whole arrangements, it challenges comparison with, any the world can show. Such an instrument ought to enshrine itself in an outward frame that should correspond in some measure to the grandeur and loveliness of its own musical character. It has been a dream of metaphysicians, that the soul shaped its own body. If this many-throated singing creature could have sung itself into an external form, it could hardly have moulded one more expressive of its own nature. We must leave to those more skilled in architecture the detailed description of that noble _facade_ which fills the eye with music as the voices from behind it fill the mind through the ear with vague, dreamy pictures. For us it loses all technical character in its relations to the soul of which it is the body. It is as if a glorious anthem had passed into outward solid form in the very ecstasy of its grandest chorus. Milton has told us of such a miracle, wrought by fallen angels, it is true, but in a description rich with all his opulence of caressing and ennobling language:--