The dome had originally been filled by Thornhill with eight scenes from the life of St. Paul. He received for them the not very munificent but quite adequate sum of 40s. per square yard. They soon began to show symptoms of decay, and Mr. Parris, the painter, invented an apparatus by which they could easily be repaired, but no funds could then be found; yet when the paintings fell off in flakes, much money and labour was expended on the restoration, which has now proved useless. Mr. Penrose has shown that so ignorant was Sir James of perspective, that his painted architecture has actually the effect of making Wren's thirty-two pilasters seem to lean forward.
Much has already been done in St. Paul's. Two out of the eight large spandrel pictures round the dome are already executed. There are eventually to be four evangelists and four major prophets. Above the gilt rails of the whispering gallery an inscription on a mosaic and gold ground has been placed. A marble memorial pulpit has been put up. The screen has been removed, and the organ, greatly enlarged and improved, has been divided into two parts, which have been placed on either side of the choir, above the stalls; the dome is lighted with gas; the golden gallery, ball, and cross have been re-gilt. The great baldachino is still wanting, but nine stained-glass windows have been erected, and among the donors have been the Drapers' and Goldsmiths' Companies; there are also memorial windows to the late Bishop Blomfield and W. Cotton, Esq. The Grocers', Merchant Taylors', Goldsmiths', Mercers', and Fishmongers' Companies have generously gilt the vaults of the choir and the arches adjoining the dome. Some fifty or more windows still require stained glass. The wall panels are to be in various places adorned with inlaid marbles. It is not intended that St. Paul's should try to rival St. Peter's at Rome in exuberance of ornament, but it still requires a good deal of clothing. The great army of sable martyrs in marble have been at last washed white, and the fire-engines might now advantageously be used upon the exterior.
A few figures about the dimensions of St. Paul's will not be uninteresting. The cathedral is 2,292 feet in circumference, and the height from the nave pavement to the top of the cross is 365 feet. The height of St. Peter's at Rome being 432 feet, St. Paul's could stand inside St. Peter's. The western towers are 220 feet high. From east to west, St. Paul's is 500 feet long, while St. Peter's is 669 feet. The cupola is considered by many as more graceful than that of St. Peter's, "though in its connection with the church by an order higher than that below it there is a violation of the laws of the art." The external appearance of St. Paul's rivals, if not excels, that of St. Peter's, but the inside is much inferior. The double portico of St. Paul's has been greatly censured. The commissioners insisted on twelve columns, as emblematical of the twelve apostles, and Wren could not obtain stones of sufficient size; but (as Mr. Gwilt observes) it would have been better to have had joined pillars rather than a Composite heaped on a Corinthian portico. In the tympanum is the Conversion of St. Paul, sculptured in high relief by Bird; on the apex is a colossal figure of St. Paul, and on the right and left are St. Peter and St. James. Over the southern portico is sculptured the Phœnix; over the north are the royal arms and regalia, while on each side stand on guard five statues of the apostles. The ascent to the whispering gallery is by 260 steps, to the outer and highest golden gallery 560 steps, and to the ball 616 steps. The outer golden gallery is at the summit of the dome. The inner golden gallery is at the base of the lantern. Through this the ascent is by ladders to the small dome, immediately below the inverted consoles which support the ball and cross. Ascending through the cross iron-work in the centre, you look into the dark ball, which is said to weigh 5,600 pounds; thence to the cross, which weighs 3,360 pounds, and is 30 feet high. In 1821-2 Mr. Cockerell removed for a time the ball and cross.
From the haunches of the dome, says Mr. Gwilt, 200 feet above the pavement of the church, another cone of brickwork commences, 85 feet high and 94 feet diameter at the bottom. This cone is pierced with apertures, as well for the purpose of diminishing its weight as for distributing the light between it and the outer dome. At the top it is gathered into a dome in the form of a hyperboloid, pierced near the vertex with an aperture 12 feet in diameter. The top of this cone is 285 feet from the pavement, and carries a lantern 55 feet high, terminating in a dome whereon a ball and (Aveline) cross is raised. The last-named cone is provided with corbels, sufficient in number to receive the hammer-beams of the external dome, which is of oak, and its base 220 feet from the pavement, its summit being level with the top of the cone. In form it is nearly hemispherical, and generated by radii 57 feet in length, whose centres are in a horizontal diameter passing through its base. The cone and the interior dome are restrained in their lateral thrust on the supports by four tiers of strong iron chains (weighing 95 cwt. 3 qrs. 23 lbs.), placed in grooves prepared for their reception, and run with lead. The lowest of these is inserted in masonry round their common base, and the other three at different heights on the exterior of the cone. Over the intersection of the nave and transepts for the external work, and for a height of 25 feet above the roof of the church, a cylindrical wall rises, whose diameter is 146 feet. Between it and the lower conical wall is a space, but at intervals they are connected by cross-walls. This cylinder is quite plain, but perforated by two courses of rectangular apertures. On it stands a peristyle of thirty columns of the Corinthian order, 40 feet high, including bases and capitals, with a plain entablature crowned by a balustrade. In this peristyle every fourth intercolumniation is filled up solid, with a niche, and connection is provided between it and the wall of the lower cone. Vertically over the base of that cone, above the peristyle, rises another cylindrical wall, appearing above the balustrade. It is ornamented with pilasters, between which are two tiers of rectangular windows. From this wall the external dome springs. The lantern receives no support from it. It is merely ornamental, differing entirely, in that respect, from the dome of St. Peter's.
In 1822 Mr. Horner passed the summer in the lantern, sketching the metropolis; he afterwards erected an observatory several feet higher than the cross, and made sketches for a panorama on a surface of 1,680 feet of drawing paper. From these sheets was painted a panorama of London and the environs, first exhibited at the Colosseum, in Regent's Park, in 1829. The view from St. Paul's extends for twenty miles round. On the south the horizon is bounded by Leith Hill. In high winds the scaffold used to creak and whistle like a ship labouring in a storm, and once the observatory was torn from its lashings and turned partly over on the edge of the platform. The sight and sounds of awaking London are said to have much impressed the artist.
On entering the cathedral, says Mr. Horner, at three in the morning, the stillness which then prevailed in the streets of this populous city, contrasted with their midday bustle, was only surpassed by the more solemn and sepulchral stillness of the cathedral itself. But not less impressive was the development at that early hour of the immense scene from its lofty summit, whence was frequently beheld "the forest of London," without any indication of animated existence. It was interesting to mark the gradual symptoms of returning life, until the rising sun vivified the whole into activity, bustle, and business. On one occasion the night was passed in the observatory, for the purpose of meeting the first glimpse of day; but the cold was so intense as to preclude any wish to repeat the experiment.
Mr. Horner, in his narrative, mentions a narrow escape of Mr. Gwyn, while engaged in measuring the top of the dome for a sectional drawing he was making of the cathedral. While absorbed in his work Mr. Gwyn slipped down the globular surface of the dome till his foot stopped on a projecting lump of lead. In this awful situation, like a man hanging to the moon, he remained till one of his assistants providentially saw and rescued him.
The following was, if possible, an even narrower escape:—When Sir James Thornhill was painting the cupola of St. Paul's Cathedral, a gentleman of his acquaintance was one day with him on the scaffolding, which, though wide, was not railed; he had just finished the head of one of the apostles, and running back, as is usual with painters, to observe the effect, had almost reached the extremity; the gentleman, seeing his danger, and not having time for words, snatched up a large brush and smeared the face. Sir James ran hastily forward, crying out, "Bless my soul, what have you done?" "I have only saved your life!" responded his friend.
Sir James Thornhill was the son of a reduced Dorsetshire gentleman. His uncle, the well-known physician, Dr. Sydenham, helped to educate him. He travelled to see the old masters, and on his return Queen Anne appointed him to paint the dome of St. Paul's. He was considered to have executed the work, in the eight panels, "in a noble manner." "He afterwards," says Pilkington, "executed several public works—painting, at Hampton Court, the Queen and Prince George of Denmark, allegorically; and in the chapel of All Souls, Oxford, the portrait of the founder, over the altar the ceiling, and figures between the windows. His masterpiece is the refectory and saloon at Greenwich Hospital. He was knighted by George II. He died May 4, 1734, leaving a son, John, who became serjeant painter to the king, and a daughter, who married Hogarth. He was a well-made and pleasant man, and sat in Parliament for some years."
The cathedral was artificially secured from lightning, according to the suggestion of the Royal Society, in 1769. The seven iron scrolls supporting the ball and cross are connected with other rods (used merely as conductors), which unite them with several large bars descending obliquely to the stone-work of the lantern, and connected by an iron ring with four other iron bars to the lead covering of the great cupola, a distance of forty-eight feet; thence the communication is continued by the rain-water pipes, which pass into the earth, thus completing the entire communication from the cross to the ground, partly through iron and partly through lead. On the clock-tower a bar of iron connects the pine-apple on the top with the iron staircase, and thence with the lead on the roof of the church. The bell-tower is similarly protected. By these means the metal used in the building is made available as conductors, the metal employed merely for that purpose being exceedingly small in quantity.