In No. 352, we gave a popular description of the interior of the Colosseum; but the reader's attention was therein directed to the splendid effect of the panorama or picture, whilst the means by which the painting was executed have been reserved for our present Number. This we have endeavoured to illustrate by the annexed engraving; and the explanation will be rendered still clearer by reference to No. 352, wherein we have given an outline of the difficulties with which the principal artist, Mr. Parris, had to contend in painting the panorama. We, however, omitted to state an obstacle equally formidable with the _reconciliation_ of the styles of the several artists engaged to assist Mr. Parris. This additional source of perplexity was the great change, almost amounting to the vitrification of enamel colours, which occurred in the hues of the various pigments, according to the point of view, and the immense distance of the canvas from the spectator. Besides furnishing the reader with the construction of the apartments, galleries, and ascents of the interior, the engraving presents some idea of the scaffoldings, bridges, platforms, and other mechanical contrivances requisite for the execution of the picture. The spiral staircase, it will be seen, leads to the lower gallery for viewing the picture. Unconnected with the intermediate gallery, there is a communication from the lowest gallery to the highest, and thence to the refreshment-rooms and exterior of the dome. The ascent to the second price gallery is by a spiral staircase under those already mentioned. The column, or central erection, containing these staircases and the ascending-room, is of timber, with twelve principal uprights seventy-three feet high, one foot square, set upon a circular curb of brickwork, hooped with iron, and further secured by bracing, and by two other circular curbs, from the upper one of which rises a cone of timbers thirty-four feet high, supporting the refreshment-rooms, the identical ball, and model of the cross, of St. Paul's, Mr. Hornor's sketching cabin, staircase to the exterior, &c. Without the circle of timbers already described, is another of twenty-four upright timbers; and between these two circles the staircases wind. The architectural fronts of the galleries form frame-works, through which the spectator may enjoy various parts of the panorama, as in so many distinct pictures.