Soane was Professor of Architecture at the Royal Academy of Arts from 1806 until his death in 1837. He took his lecturing there very seriously and had hundreds of drawings made, which were the equivalent of a slide or PowerPoint show. They were strong, powerful images to make a particular point, often copied from existing prints or illustrations. They were held up as Soane spoke. His friend J M W Turner, the greatest English painter of the time, considered it an honour to hold them up for him. Unfortunately, it seems that Soane spoke too fast as he gave the lectures. There would be lots of work in the office to get the drawings all done. This drawing, made by one of Soane’s assistants, Charles Tyrrell, in 1814, shows the comparative sizes of famous domes. The smallest is a section of Soane’s own design for the Rotunda at the Bank of England built in 1785. The next is an elevation of the Radcliffe Library in Oxford designed by James Gibbs and built in 1748, then a section of the Pantheon in Rome (drawings of which you can see in Elevation: The Pantheon; Plan: The Pantheon; Section: The Pantheon) built in the early 2nd century AD. The largest is an elevation of the dome of St Peter’s, by Michelangelo, also in Rome, completed in 1590. See how cleverly the draughtsman shows the different sizes of the domes.
This is part of Soane’s Royal Academy Lecture VI which concerned domes; here is what he said:
The ancient architects, fully impressed with the beauty and importance of domes, constructed them with durable materials and in the most scientific manner. Had it not been so the astonishing dome of the Pantheon, the light and elegant dome of the Temple of Minerva Medica, those in the baths of Diocletian, that at St Rémy, as well as many others, would only have been known to us in the annals of the historian.
There is also a very uncommon specimen of dome at Ravenna which forms the roof of the Basilica of Hercules or, as called by others, the Mausoleum of Theodoric. This dome although nearly twenty feet in diameter and weighing between eight and nine hundred tons, is notwithstanding formed out of one piece of marble. The ancients confined the domical form of covering to buildings whose plans are square, polygonal, or circular. These hemispherical roofs were sometimes left open at [the] top for light, as in the Pantheon and in other ancient buildings, but the domes of the Temple of Minerva Medica of the Mausoleum at St Rémy as well as those of the Baths of Diocletian, are all complete hemispheres, whilst in other buildings domes are terminated, as directed by Vitruvius, with some characteristic ornament: at the Mole of Hadrian with a pineapple, and at the Tower of the Winds with a Triton holding in his hand a wand.
There is also a very distinct species of dome to be seen in the church of Sta Sophia at Constantinople for which happy invention we are indebted to two Grecian architects Anthemius and Isidorus. This dome though less simple than those in ancient buildings, is far superior in lightness of appearance and boldness of construction. This dome, resting in four arches, springing from as many large piers, makes on its ichnographic projection a perfect square, whose concave surfaces gradually increasing from its base, form a complete circle, on reaching the crown of the four arches. Thus the entire dome, reposing on four points, seems rather suspended in the air than supported by the piers. The domes of the ancients seem always to grow out of the substruction and to harmonize and unite with it in the most gradual and pleasing manner, forming as it were a canopy to the whole edifice.
In many modern structures domes seem to be placed on the roofs without any visible support and without any apparent connection with the other parts of the edifice, as at St Peter’s in Rome, St Paul’s in London, the church of the Invalides in Paris, and other examples. It must likewise be remarked that modern domes, instead of being terminated with light appropriate ornaments, as in ancient works, are now often surcharged with lanterns of very considerable dimensions, both in bulk and height.
However general this fashion may now be, it is not less deserving of censure, for as the dome represents the roof of a square, polygonal, or circular building, in the manner as the pediment designates the roof of a rectangular structure, how can we add a lantern, or any other building, on a dome? If the architects at Tralles were formerly reproved for having represented in a scene only, columns and pediments on the roofs of their buildings, if one of these barbarous monstrosities had been raised upon the dome of the Pantheon, would not every man of taste in antiquity have exclaimed against such a prosperous addition? Such an addition was only prevented by the death of Alexander the Seventh.
