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. INDEX. Abbot, Bishop of London, 11, 14; Archbishop of Canterbury, 24 Académie Royale des Sciences, 148 Addison, 74, 179 All Hallows, Bread Street, rebuilt by Wren, 232; destruction of, 232, 234 -- -- Lombard Street, rebuilt by Wren, 271, 272 -- -- Thames Street, 240 All Saints, Isleworth, 298