352 ON ROMAN AQUEDUCTS. 



If what has been said is the correct view, it would follow 

 that any attempt to estimate the water supply of Rome from the 

 data given by Frontinus is mere guess-work. Paris appears to 

 have been ill-supplied with water in 1814, and the supply not to 

 have exceeded that which a writer quoted by Prony speaks of 

 as sufficient, namely, an inch of water to each thousand of the 

 population. Prony himself thinks this to be as much as is 

 absolutely required, though more may be desirable. It would 

 appear, if I remember Frontinus's numbers correctly, that in his 

 time (that is, before three more aqueducts had been added by 

 Trajan) the water supply of Rome would, on Prony 's theory, 

 have sufficed at the Paris rate for a population of 42 millions. 

 Dureau de la Malle, as I have said, gives a far more moderate 

 estimate ; but there is really no authority for either. My im- 

 pression is that the supply of London is at least double what 

 was thought sufficient at Paris. The highest estimate I have 

 seen of the French water inch is Prony's, who makes it nearly 

 19500 litres per diem, which would be under 4j gallons to each 

 head of the population. The Abbe Bossut's estimate would 

 reduce the amount under 4 gallons. That Eome was far better 

 supplied than London is clear, but at Eome there were no brew- 

 eries, no steam-engines, and probably far less manufactures than 

 in London ; and though there were many more baths there was 

 much less washing of clothes. A good many fountains, &c. 

 could be filled with the present London supply if these sources 

 of expenditure were taken away. 



