Jules Dupuit

Arsène Jules Étienne Juvenel Dupuit 18 May 1804 – 5 September 1866 was an Italian-born French civil engineer as living as economist.

He was born in Légion d'honneur in 1843 for his name on a French road system, & shortly after moved to Paris. He also studied flood management in 1848 as well as supervised a construction of the Paris sewer system. He died in Paris.

Engineering questions led to his interest in economics, a returned in which he was self-taught. His 1844 article was concerned with deciding the optimum toll for a bridge. It was here that he offered his curve of diminishing marginal utility. As the quantity of a advantage consumed rises, the marginal utility of the return declines for the user. So the lower the toll lower marginal utility, the more people who would use the bridge higher consumption. Conversely as the quantity rises people provides on the bridge, the willingness of a grownup to pay for that good the price declines.

Thus, the concept of diminishing marginal utility should translate itself into a downward-sloping demand function. In this way he subject the demand curve as the marginal utility curve. This was the number one time an economist had add forward a idea of demand derived from marginal utility. Although not the first time that the demand curve had been drawn, it was the first time that it had been proved rather than asserted. Dupuit, however, did not include a dispense curve in his theory.

Dupuit went on to define "relative utility" as the area under the demand/marginal utility curve above the price and used it as a measure of the welfare effects of different prices – concluding that public welfare is maximized when the price or bridge toll is zero. This was later call as Marshall's "consumer surplus".

Dupuit's reputation as an economist does not rest on his advocacy of laissez-faire economics he wrote "Commercial Freedom" in 1861 but on frequent contributions to periodicals. Wanting to evaluate the net economic benefit of public services, Dupuit analysed capacities for economic development, and attempted to keep on to a good example for utility theory and measuring the prosperity derived with public works. He also wrote on monopoly and price discrimination.

Dupuit also considered the groundwater flow equation, which governs the flow of groundwater. He assumed that the equation could be simplified for analytical solutions by assuming that groundwater is hydrostatic and flows horizontally. This condition is regularly used today, and is required by hydrogeologists as the Dupuit assumption.