600 The Architectural Review and American Builders' Journal. [Mar., the dome. This was the conception of Michael Angelo , and so completely did it possess his mind, that he might have truly said : — " Still shall thou be my waking theme ; Thy glory still my midnight dream." And a glorious creation it is, when taken by itself, apart from all detracting sur- roundings. As we have seen at St. Sophia's, the idea of construction, in domes, was on strong piers, arched together on the square, and the circle, or ring, made up of corbeling. The architects of succeed- ing generations continued this practice, up to the time of which we write. Mi- chael Angelo at once produced a grander effect, by substituting for the corbeling, double consoles. On these, he con- structed a small cornice, which served as an impost for eight arches, upon the upper part of which he built the dome. Externally, the plinth is an octagon ; internally, a circle. "The diameter of the octagon is 192 feet 9 inches, that of the circle, 13-4 feet % inches. The thick- ness of this plinth at its lesser section, is 29 feet 3 inches. On this plinth, is a circular stylobate, 28 feet 6^ inches thick. This thickness is divided by pas- sages, respectively 5 feet 10 inches, and 2 feet 10 inches wide. These latter form flights of steps, communicating with the four spiral staircases formed in the thickness of the wall of the drum of the dome, which is raised up by the cir- cular stylobate 12 feet 4^ inches, and is 1 feet thick. The construction is of broken brick and rubble masonry , the interior being formed of hard bricks stuccoed. Exter- nally, the work is faced with thin slabs of Travertine stone, which was, by order of Sixtus the Fifth, covered with lead ; and the iron bands, with which the brick- work was held together, with bronze gilt. These iron bands are 3 inches wide, by If inches thick. The visitor to St. Peter's will observe, as he surveys the interior of the dome from above, several cracks of a seem- ingly dangerous nature, in the wall or ceiling of the dome. These were caused by the hurried manner in which the work was done, the mortar not get- ting time to set. Settlement was the natural consequence ; and to such an extent did the mischief go, that the iron band surrounding the inner circle was fractured. This, however, was repaired , and six additional circles placed around the outer dome, so as to render it per- fectly secure. St. Paul's Cathedral, London, shows another great construction of dome, which may well rank foremost, as a won- der of mechanical design, and skill of execution. Although less in size than St. Peter's, it does not lose any thing in the comparison, on the score of con- struction, proportion, and general effect. We do not propose to enter into de- tail on the subject of the construction of this beautiful dome, of the great Lon- don Cathedral ; but will shortly proceed, with our reader, to survey the vast ad- vantages, which progressing science has thrown around such constructions in this our day. The Dome of the Capitol at Washington exhibits a variety of construction entirely different from any to which we have alluded, being fashioned wholly of iron ; we do not, however, pro- pose to extend the present paper by speaking in detail of that structure ; preferring to reserve it for a future article. The Pacha of Eg3^pt is having a thea- tre built in the principal square in Cairo. No less than 7,500 workmen -are labor- ing at it day and night. The architect has received orders to have it finished in two months. And for what has this enormous work been undertaken ? Sim- ply in hopes of inducing Mme. Schnei- der to accept an engagement on its boards! In brief, the offer made the fair enslaver is the munificent one of 50,000fr. for ten performances, without reckoning perquisites.
