Note 158 — APPENDIX TO CHAPTER IV. PART I. THE NINE AQUEDUCTS IN THE TIME OF FRONTINUS.
Reading edition
It is of little consequence, but perhaps it may be interesting to know more accurately the result of the calculation. If we take 1.25 as the diameter of the quinary, and multiply the square of this by 0.7854 (the corrected ratio), we obtain the result in square digits, 1.22718. This multiplied by the 1825 gives 2239.6, that is, the result within one digit as given by Frontinus.