In extent and accuracy, the Panorama is one of the most surprising achievements of art in this or any other country. The picture covers upwards of 40,000 square feet, or nearly an acre of canvass; the dome of the building on which the sky is painted, is thirty feet more in diameter than the cupola of St. Paul's; and the circumference of the horizon from the point of view, is nearly 130 miles. The painting is almost completed; indeed, sufficiently so, for the general effect; although this will be considerably increased by the insertion of the remaining details, and the last or finishing touches. Much as the spectator will be struck by the fidelity of the representation, there is one claim it has to his admiration, which has only to be explained to be universally acknowledged. It is simply this. Only let such of our readers as have ascended the galleries of St. Paul's, think of the fatigue they experienced in the toil, and comparatively speaking, the little gratification they experienced on their arrival at the summit. In short, what had they for their pains but the distinct roofs of the houses in the immediate vicinity, while the rest of the city was half lost in fog and the smoke of "groves of chimneys." The only period at which London _can be seen_, is at sun-rise on a fine summer morning--such a morning, for instance, as that of the last Coronation. This too must be before the many thousand fires are lighted--exactly the period at which it is impossible to gain admittance to the cathedral. In the Panorama of the Colosseum, therefore, alone it is that we can see the "mighty heart," the town we inhabit; and for this grand scene we are indebted to the indefatigable genius of Mr. Hornor.[2] The magnificent effect of the Panorama, however, baffles all description of our pen. Indeed, the scene gives rise to so many inspiring associations in an enthusiastic mind, that few Englishmen, and still fewer Londoners, are equal to the detail of its description. Every inch of the vast circumference abounds with subject for reflection. The streets filled with passengers and vehicles--the grandeur of the public buildings, churches, and palatial structures--the majestic river winding grandly along, with the shipping, vessels, and gay trim of civic barges gliding on its surface, its banks studded with splendid hospitals, docks, and antique towers--and its stream crossed with magnificent bridges--till it stretches away beyond the busy haunts of industry, to the rural beauties of Richmond, and the castellated splendour of Windsor. Of course, the river is the most attractive object in the painting; but overlooking the merits of the town itself, and the world of streets and buildings--the representation of the environs is delightfully picturesque, and the distances are admirably executed; while the whole forms an assemblage of grandeur, unparalleled in art, as the reality is in the history of mankind.