Picard
ORDERBY-NAME: Picard, Jean
OTHER-NAME: none
BIRTH: 21 July 1620; La Fleche, France
DEATH: 12 October 1682; Paris, France
CATEGORY: Natural Sciences & Mathematics
DISCIPLINE: Astronomy; Cartography; Instrumentation
ASSESSMENT: Jean Picard is regarded as the founder of modern astronomy in France.
LANGUAGE: French
EDUCATION: Jesuit College at La Fleche; M.A., University of Paris (1650)
ACHIEVEMENTS: He was one of the first scientists to use scientific methods in the making of maps. His most significant achievement was accurately measuring an arc of a meridian of the earth.
MAJOR-WORK/S: Mesure de la terre; Connaissance des temps (annual publication)
PARENTS: Jean Picard (bookseller); mother unknown
SPOUSE: none
SIBLINGS: none
CHILDREN: none
DETAILS: Little is known of Picard’s childhood. He earned his M.A. degree from the University of Paris in 1650.
It is known that he was ordained a priest in 1650, and served as a prior of Rille in Anjou, France. As a pupil of <taught by> Gassendi*, he made astronomical observations with him in Paris between 1645 and 1652. Gassendi and Picard successfully observed a solar eclipse in August of 1645.
In 1655 left Anjou to accept the position of professor of astronomy at the College de France. Though he wasn’t a founding member, Jean was inducted in to the Academie Royale des Sciences in 1666, shortly after its inception. There is evidence suggesting that a renowned astronomer and physicist of that time period, Adrien Auzout, was responsible for Picard’s appointment to the Academie.
His annual pension for Academie work was 1200 livres; this was raised to 1500 livres in 1669. He devoted himself entirely to working for the Academie for life and his scientific accomplishments were many.
He invented a movable-wire micrometer, which fitted onto the front end of a telescope and was used to measure the diameters of the sun, moon, and planets. He utilized <used work of> Snell*’s method of triangulation to improve the accuracy of measurements of the earth. He was also responsible for applying use of an astronomical telescope into survey instruments such as the quadrant.
In addition, Picard invented a new leveling instrument that also contained a telescope and which served as the standard for leveling for many years. Picard was one of the first to approach cartography, the science of map-making, in a scientific manner. He created an accurate map of Paris and collaborated with others, including Roberval* and <collaborated with> Haukesbee*, to do the same for France.
Picard’s most significant accomplishment was the accurate measurement of one arc of a meridian of the earth. A meridian is an imaginary circle drawn through both the south and north poles and one other point on earth.
Jean’s arc was the distance from Sourdon, France to Malvoisine, France, south of Paris. He measured this distance as 57060 toises (a toise being about 6.4 feet). Modern day experts have determined that Picard’s result was very accurate, being only approximately 90 feet short.
Picard wrote about his measurements in Mesure de la Terre (1671). His work had a noteworthy impact on <influenced> Newton*. With Picard’s measurements, Newton was able to revise his own calculations and publicize his famous Law of Universal Gravitation.
Also in 1671, Jean traveled to the island of Hven, Sweden, to study at fellow astronomer <studied at astronomy of> Brahe*’s observatory. There, he helped determine the observatory’s exact location. This observation led to the possibility of the aberration of light.
Picard’s modesty allowed him to recommend to <supported> Cassini*’s appointment as director of the new Paris observatory to <worked for> Louis XIV*. The observatory’s construction was suggested by Auzout.
Another Academie project in which Picard played a major role was in surveying and carrying out the successful supply of water to the fountains at Versailles.
Picard’s many talents, discoveries, and unfettered devotion to his work leave him regarded as the founder of modern French astronomy and one of its most significant contributors.
EXTRA CONNECTIONS: None
ONELINER: Jean Picard, founder of French astronomy
BIBLIOGRAPHY:
O’Connor, J.J. and Robertson, E.F., Jean Picard. Retrieved December 5, 2003, from http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Picard_Jean.html
Wolf, William. Geschichte der Astronomie (Munich, 1879); Delambre, Hist. De l’astr., mod. II (Paris 1821), 567-632. Transcribed by WGKofron. Retrieved December 5, 2003 from Online Edition of The Catholic Encyclopedia, Volume XII, http://www.newadvent.org/cathen/12073b.htm
Westfall, Richard S., Jean Picard. Retrieved Online December 6, 2003 from http://es.rice.edu/ES/humsoc/Galileo/Catalog/Files/picard.html