Set half Hemispherical Arches, such as we make the heads of Niches, but lay’d back to back, so that each of these have its Bearing upon three Pyramids of the Lower Order, that is two angular ones and the middle Pyramids; and these cutting one another upon the Diagonals will have a firm bearing for all the Works above.
Pliny mentions a Brass Circle and Cupola, lay’d upon the Five Lower Pyramids, not I suppose to bear anything, but chiefly for Ornament, and to cover the stone work of the Arches upon the strong Spandrells of which if another Platform were rais’d upon that might the upper structure be built and the whole have a stupendious effect, and seemingly very open. Pliny took his Description of this extraordinary Pile from the Measures set down by Varro, a diligent and therefore credible author, who probably might have taken his Dimensions when it was standing before the absolute conquest of Etruria by the Romans; the summary then of this prodigious Edifice (erected to show the Vanity of the Eastern Monarchy could be exceeded by the Italians) may be thus compriz’d.
The Basis of the whole was 300 ft. square, and 50 ft. high; upon which stood Five Pyramids each of 75 ft. square at 150 ft. high; upon which rested the Brazen Circle and Cupola, stil’d by Pliny Petasus, (which I take to be a Brass Covering securing the Arches) from which hung little Bells by Chains, which sounded as they mov’d by the Winds.
The Four Pyramids of the Second Order of 100 ft. high standing upon the Circle or Brim of the Petasus as upon an Entablature, were evidently the Four First Angular Pyramids continu’d to an Apex, or near to a Point, so each will be in all from the Basis 450 ft. high, and rise as high as the Petasus; above which was again a Platform containing the Third Order of Five more Pyramids, of which the four angular Pyramids rested firmly upon the keys of the Diagonal Sections of the half Hemispherical Vaultings, which were called by the Ancients Conchae resembling the heads of Niches joyn’d back to back. This Platform I take to have been round as being the Horizontal Section of the Petasus; and the Bases of the Five Upper Pyramids would be contiguous, and thus would be of the same shape and as high as the same below, as Varro asserts with some suspicion, fearing how they would stand, but I with confidence, the Proportions persuading, which indeed are very fine.
The Heighth to the Breadth of the Basis is 6 to 1. The Heighth of the Pyramids to the Brass Petasus is 2 to 1, but taking in their whole heighth it would have 4 to 1, but allowing the Point of the Pyramid to be taken off (as it ought) and allowing for the Brasen Brim and Bells it will be 250 foot, above which was the Floor that bore the Five upper Pyramids of 4 to 1, so the Heighth is 550 foot as 6 to 11.
I have ventured to put some Ornaments, at ye Top belonging to the Tuscan superstition, (They then us’d not Statues) They are Golden Thunderbolts, so the whole will be 600 foot high, that is double to the Basis and the Heighth to the Brass circle will appear half the Face, or like the Façade of a Tuscan Temple, to which the Breadth of the Brim of the Petasus and the Bells supply the Place of an Entablature:
I have been the longer in this Description because the Fabrick was in the Age of Pythagoras and his School, when the World began to be fond of Geometry and Arithmetick.
N.B. In all the Editions of Pliny for Tricenum read Tricentinûm as the sense requires.
At the end of the Discourse on Architecture is an elevation, drawn in pen and sepia, of the tomb of Mausolus, as Sir Christopher supposed from Pliny’s account that it must have been constructed. It is drawn to a scale, with indications of statues, of which he supposed there to have been forty-eight. It is remarkable how closely Sir Christopher’s conjectural elevation tallies with what recent excavations have brought to light.