15. Memorandum, That in Nero's time, as Monsr. Chivreau reporteth, there died 300 thousand People of the Plague in Old Rome; Now if there died 3 of 10 then, and there, being a hotter Countrey, as there dies 2 of 10 at London, the number of People at that time, was but a million, whereas at London they are now about 700 thousand. Moreover the Ground within the Walls of Old Rome was a Circle but of 3 Miles diameter, whose Area is about 7 square Miles, and the Suburbs scarce as much more, in all about 13 square Miles, whereas the built Ground at London is about 9 square Miles as |20| aforesaid; which two sorts of proportions, agree with each other, and consequently Old Rome seems but to have been half as big again as the present London, which we offer to Antiquaries. ||
- Petty's use of Chevreau's estimate argues no knowledge of the Histoire du Monde (Paris, 1686, 2 v. 4°) beyond what he might have drawn from Bayle's words, " II s'étend beaucoup sur la magnificence de Rome... Il croit qu'il's'y est trouvé près de quatre millions d'habitans, & il reporte que les trois cens mille personnes qui y moururent de peste en une Automne sous le regne de Neron, ne firent pas remarquer que le nombre des habitans fût devenu moindre. République des Lettres, Nov., 1686, Oeuvres, i. 680.