(b.France, 1611; d. France, 1680)
Very little is known about the personal life of Pierre Perraulot, who was rather overshadowed, at least during his lifetime, by his three younger brothers: Claude (1613–1688), a physician, scientist, and the and the architect of the Louvre; Nicholas (1624–1662), a noited theologian; and Charles (1628–1703), a critic and the author of the Mother Goose fairy tales. Pierre, following in his father’s footsteps, became a lawyer and joined the government service as an administrator. He bought the post of receiver-general of finances for Paris. His timing was rather unfortunate, for Louis XIV soon remitted the tailles due for the previous ten years. Perrault, along with other tax collectors, encountered financial difficulties. He borrowed on the current year’s (1664) revenue and was caught in the act by Colbert, who was then at the height of his power. He was dismissed and was forced to sell hgis post at a loss. The affair left him almost peeniless.
It is not known how Perrault earned his living after the dismissqal. He did, however. make a very poor translatioin of Alessandro Tassoni’s Secchia rapita.
The book Del’origine des fontaines was published anonymously at Paris in 1674. Its authorship, the subject of considerable controversy in the past, has been vaiously atrtributed to André Félibien,. enis Papin,. and finally to its true author, Perrault in it he revieed the vaious earlier huypotheses on the origin of spring and proposed an experimental investigation to prove that rainfall alone is sufficient to sustain the flow of springts and rivers throughout the year. Perrault considered the Seijn River, from, its source to Aynayle-Duc (now Aignay-le-Duc), determining the total drainage area for that portion and makintg observations of annual rainfall. Using the average annual rainfall, he estimated the total volume of water that precipitated over the drainage area. The losses due to “feeding the tress, herbs, vapours, [and] extraordinaryswellings of the river when it rains” were deducted from this figure to obtain sustained runoff. The total annual flow of the Seine was estimated by comparing its flow with that of the Gobelins River near Versailles, which had been measured previously. Having determined the total annual rainfall over the entire drainage area of the River Seine and the total annual flow of the river itself, Perrault experimentally demonstrated that only one-sixth of the annual rainfall was necessary to sustain the river flow. Thus for the first time it was scientifically proven that rainfall is more than adequate to supply river flow.
But Perrault did not believe in the general in filtratioin of rainwater aned thereby, recharge of groundwater. He went to great lenths to find evidence of general infiltratioin, and from his observatioins he concluded that it was only an occasional and local phenmomenon. In the begining of the second part of his book, Perrault differentiated his own view from that held by Vitruvius, Gassendi, Pallisy, and Jean Francois, which he referred to as “general opinion.” He objected to their concept of infiltration of rainwater into the earth and said that he did not believe that there is enough precipitation for the earth to be soaked with it as much as necessary, and still leave over a sufficient quantity to cause rivers and springs.
Perrault’s experimental work on the rainfall and runoff of the Upper Seine is a milestone in the history of hydrology. Admittedly his experimendal techniques were somewhat crude and his figures could have been more refined, but his reasoning was flawless, his method irrefutable, and his was the first experimentaion to prove categorically that rivers originated from rainfall. Edmé Mariotte later used more sophisticated measuring techniques to confirm Perrault’s findings. The second half of the concept of the hydrologic cycle, that enough water evaporated from oceans and rivers to come down as rainfall, was experimentally proved by Edmond Halley. Biswas, in his History of Hydrology, has suggested that Perrault, Mariuotte, and Halley should be considered as cofounders of experimental hydrology. But when it is considered that Mariotte and Halley were familiar with Perrault’s work and may have been considerably influenced by it, Perrault’s contributions to hydrology become all the more important.
An international symposium on the history of hydrology was held at Paris in 1974, by the International Hydrological Decade, to mark the tricentenary of the publication of Perrault’s trailblazing book.
I. Original Works. Perrault’s major writing is De l’oriegine des fontaines (Paris,1674), trans. by A. LaRocque as On the Origin of Springs (New York, 1967). He also translated Alessandro Tassoni’s La secchia rapita as Le seau enlevé (Paris, 1678),
II. Secondary Literature. See Asit K.Biswas, “Begining of Quantitative Hydrology,” in Journal of the Hydraulics Division, American Society of Civil Engineers 94 (1968), 1299–1316; and History of Hydrology (Amsterdam, 1970), 208–213; and S. Delorme, “Pierre Perrault,” in Archives internatioinal d’histoire des sciences27 , no. 3 (1948), 388–394.
Margaret R. Biswas
Asit K. Biswas