Born: 20 September 1674 in Bologna, Papal States (now Italy)
Died: 15 February 1739 in Bologna, Papal States (now Italy)

Eustachio Manfredi's father, Alfonso Manfredi, was a lawyer in Bologna. Alfonso, who came originally from Lugo, which is about 40 km east of Bologna, married Anna Maria Fiorini on 23 October 1670, and they had four sons and two daughters. It was a remarkable family for, in addition to Eustachio, his brothers Gabriele Manfredi (1681-1761) (who also has a biography in the archive) and Eraclito (1682-1759) became professors of mathematics and of astronomy respectively. His two sisters, Maddalena (1673-1744) and Teresa (1679-1767), did not receive the formal education of the boys, only receiving anelementary school education. However, they learnt from their brothers and became very knowledgeable in astronomy, mathematics and Latin. The girls devoted themselves to supporting the family, partly by undertaking domestic duties but also helping their brothers with their scientific work. They produced literary works aimed at the educated middle-class inhabitants of Bologna. The third brother, Emilio (1679-1742), became a Jesuit priest.

After attending school at the Jesuit Convent of St Lucia, Eustachio studied at the Jesuit College in Bologna. His father strongly encouraged him to study philosophy which he took in his first years but moved on to study for a law degree. He obtained a doctorate in canon and civil law, graduating on 19 April 1692. He never practiced law for, after graduating, he studied mathematics and hydraulics with Giovanni Domenico Guglielmini (1655-1710). Guglielmini had produced important contributions to crystallography beginning in 1688 and, at the time that Manfredi was studying with him, Guglielmini was studying hydraulics leading to his major work on rivers, Della Natura del Fiumi (1697) (On the Nature of Rivers), which included among other things a description of uniform flow. Guglielmini taught Manfredi the differential calculus and he soon became interested in hydraulics, but also taught himself astronomy. During these years the young Manfredi had wide interests for, in addition to these scientific studies, he also studied French, and was interested in literature, particularly poetry. All of these interests were enhanced by a group of friends with similar scholarly interests who Manfredi invited to form the Accademia degli Inquiti. The group, which included his brothers, sisters and student friends, met, starting in 1690, at the Manfredi home. Manfredi was fascinated by astronomy and led much of the groups' activities in that direction. Although they did not have funds to buy astronomical instruments, nevertheless they set up an observatory at the Manfredi home and constructed their own rudimentary sextants and telescopes. By 1694 the group had expanded to include philosophers, mathematicians and anatomists not only from Bologna but also from surrounding towns. They had to find a larger place to meet and they met from that time on at the home of Jacopo Sandri, a professor of anatomy and medicine at Bologna University. They continued to meet there for the next ten years.

As we indicated above, Manfredi was also interested in poetry and music. He wrote poetry, some of which is now lost, but an anthology of his poetry was published in the 84 page work Rime del dottore Eustachio Manfredi (1713). He also contributed to La ninfa costante (1697) and Il paradiso (1698). His poetry enjoyed great popularity with works such as the 59-page book of sacred poetry Poesie sacre di Eustachio Manfredi bolognese published in 1840. For his literary achievements he was elected to the Accademia della Crusca in 1706. This ancient academy, founded in 1583, was for linguists and philologists, and aimed to preserve the purity of the Italian language.

In 1699 Manfredi was appointed as a public lecturer in mathematics at the University of Bologna. However, this position was very poorly paid and Manfredi was in considerable financial difficulties. In particular his father had been forced to leave Bologna and the responsibility for the whole family had fallen on Manfredi. However, he was supported by Giovanni Giuseppe, the Marquis Orsi (1652-1733), a Senator of Bologna who was described by a contemporary as "one of the most knowledgeable men in Italy". In fact Orsi started up his own academy, which met in his home, and later (in 1716) he became a fellow of the Royal Society of London, proposed by Isaac Newton. From around 1700 Manfredi was also supported by Count Luigi Ferdinando Marsili (1658-1730), a soldier and naturalist who was engaged in military campaigns but, nevertheless, wished to create an academy in Bologna similar to the Royal Society in London and the Academy of Sciences in Paris. Count Marsili was occupied in mapping the Babsburg-Ottoman border following the Treaty of Karowitz and was seldom in his palace. In 1701 the whole Manfredi family moved into the Count's palace. With Marsili's support, Manfredi erected an observatory at the palace in 1703. In 1704, while continuing to hold his lectureship in mathematics at the University of Bologna, he became head of the Collegio Montalto in Bologna (later San Luigi College), which was a college for the education of Jesuit priests. In the same year he replaced Giovanni Domenico Guglielmini as superintendent of the Bolognese Water Authority and continued to hold this position for the rest of his life.

In 1704 the Accademia degli Inquiti formalised their structure and, at this time, Giambattista Morgagni (1682-1771) became its leader. In the following year meetings of the academy moved into Count Marsili's palace. From 1705 Manfredi corresponded with Guido Grandi who had been appointed to Pisa. Giovanni Cassini, who had been professor in Bologna for many years, was by this time head of the Paris Observatory but kept in close contact with developments in Bologna. In particular he corresponded with Manfredi. On 29 November 1707, jointly with Vittorio Francesco Stancari with whom he was working, Manfredi discovered a comet (now given the name C/1707 W1). They observed the comet on four occasions until 25 December 1707, the last date on which it was observed. The data from these observations shows that the comet was following a parabolic orbit.

In 1711 Manfredi was appointed to the chair of astronomy at the Institute of Sciences which had been founded by Count Marsili. He resigned his position at Collegio Montalto at this time but continued to hold his other posts. In the following year he began the building of the observatory which became the Department of Astronomy. Despite being deeply involved in these scientific positions, he continued to keep up his interest in poetry and there are numerous compositions by him over this period of his life. He composed poems on a wide range of topics - public events, religious festivals, love poems, and poems which expressed his traditional Catholic religious beliefs.

Following the building of the new Bologna Observatory, Manfredi carried out observations to calculate its precise latitude and longitude. With his assistants, he carried out three series of observations of the pole star, two series with mobile quadrants and the third with a two and a half metre wall semicircle. These gave results consistent with others which had been made earlier in different parts of Bologna. He then carried out a series of observations on stars, attempting to measure parallax. In fact he discovered that the stars appeared to move in circular orbits which he realised could not be due to parallax. He had come to these conclusions in 1719 but he did not publish these results until ten years later in De annuis inerrantium stellarum aberrationibus (1729). The reason for the delay was due to the censors in Rome who were worried that the results might be used by those claiming that the earth was not stationary. By the time it cleared the censors, James Bradley had made similar observations to those of Manfredi and, in 1729, he published his own observations together with his explanation that the phenomenon was caused by the aberration of light. Bradley's explanation required light to have a finite velocity and the earth to be in orbit round the sun. Although Manfredi had, earlier than Bradley, discovered the same phenomenon and given it the name 'aberration', he could not accept Bradley's explanation. Manfredi remained throughout his life a believer in a stationary earth in the centre of the universe.

In 1715 Manfredi, assisted by his sisters and his students, completed his two-volume Ephemerides motuum coelestium for 1715-1725 which was based on the observations of Giovanni Cassini at the Paris Observatory. Although Giovanni Cassini had produced much of the data in the tables, he had not published it. Before this time ephemerides had always been intended as astrological purposes and we must give Manfredi credit for publishing his ephemerides intending them for scientific use. The Ephemerides motuum coelestium [1]:-

... included tables of the meridian crossing of the planets, tables of the eclipses of the satellites of Jupiter and of the conjunction of the moon and the principal stars, as well as maps of the regions of the earth affected by solar eclipses. The ephemerides were preceded by a volume of instructions including tables that were reprinted by Eustachio Zanotti in 1750. In 1725 Manfredi published a similar, highly successful work for the period 1726-1750 that in some ways anticipated the Nautical Almanac (1766).

After completing the work for the ephemerides in 1714, Manfredi took up problems in hydraulics. The problem was that the Reno, a tributary of the river Po, was causing devastating floods between Bologna and Ferrara. Manfredi represented Bologna in the discussions which were set up between experts from the States of Mantua and of Venice in attempts to solve this problem. The difficulties in finding a solution were great for there were economic issues, technical issues, political issues and legal issues to overcome. Pope Clement XI called the experts to a meeting in April 1718 but the proposed solution ran into technical objections. Another meeting was called by Clement XI in 1719 which was attended by Eustachio Manfredi, his brother Gabriele Manfredi, and the mathematicians Domenico Corradi (1677-1756), Giovanni Ceva, Guido Grandi and Giovanni Saccheri. This particular effort to find a solution came to an end in March 1721 when Clement XI died.

Manfredi went to Lucca in 1724 where he was called to settle a dispute regarding boundaries. In the following year he was in Val di Chiana discussing reclamation work. Between 1730 and 1731, he was in Ravenna where he worked with Bernardino Zendrini (1679-1747), the superintendent for rivers, lagoons and bridges for the Venetian Republic, on problems with the harbour and with the river Montone which joins the Ronco before entering the sea just south of Ravenna. Between 1732 and 1733 he spent long periods in Rome advising on draining the Pontine Marshes, on ways to prevent the Tiber flooding, and on problems with the Aniene, a tributary of the Tiber. Only in 1733 did he return to his work in astronomy having been too busy with the various problems in hydraulics that had concerned him over a period of many years. His final work on astronomy included Defectus Lunae observatus (1736), Congressus Mercurij cum Sole (1736) and Defectus Solis observatus (1738). He was also interested in the research which was being undertaken on the figure of the earth and corresponded with Pierre-Louis Moreau de Maupertuis in 1734 on this topic. Over these final years of his life, Manfredi taught astronomy at the Institute where he was visited by several foreign scholars. His last work was, however, undertaken despite his deteriorating health. He began to have problems with his health in 1731 but continued working, mainly attempting to complete work which he had already started. By 1737 he was not mobile at all and could only be moved in a carriage. At this time he was forced to end making regular astronomical observations. He refused to give up work entirely and, after this, he worked on producing a handbook of Italian hydraulic engineers. The book, Della natura de' fiumi, was completed before his death and was published posthumously in 1739. It proved a very popular work and was reprinted several times until the early nineteenth century. Another two posthumous publications by Manfredi were Instituzioni astronomiche (1749) and his lectures on the elements of plane and solid geometry and trigonometry, Elementi della geometria piana e solida e della trigonometria (1755).

We have explained above how Manfredi founded the Accademia degli Inquieti, that became the Academy of Sciences of the Institute of Bologna in 1714. In addition to his membership of this academy, he was also a foreign member of the Académie Royal des Sciences, elected in 1626, and a fellow of the Royal Society of London, elected in 1729. It is interesting to see the papers by Manfredi that were read at meetings of the Royal Society. These include: Observations of the solar eclipse witnessed at Bologna on 14 September 1727 (read 16 January 1728); Observations of the moon, Venus and Saturn made at Bologna(read 16 January 1728); Observations of the eclipses of Jupiter's satellites (read 16 January 1728); Astronomical passage of a Lumen Boreale observed near Bologna March 14 1727 (read 16 May 1728); Observations of the lumen borealis seen at Bologna on 14 March 1727 (read 16 May 1728); Concerning Newton's work on optics (read 31 October 1728); Observations of lunar eclipse on 28 July 1729 (read 22 January 1729); Concerning Mr Bradley's theory about fixed stars (29 January 1729); Observations of a solar eclipse witnessed at Bologna (read 29 October 1730); Observations of the solar eclipse on 3 May 1734 (read 23 October 1735); Account of the conjunction of Mercury with the Sun observed at the Astronomical Observatory of the Institute of Bologna on 11 November 1736 drawn up by Eustachio Manfredi (read 13 January 1737).

1. G Tabarroni, Biography in Dictionary of Scientific Biography (New York 1970-1990).

Books:

1. F M Zanotti, Elogio del dottor Eustachio Manfredi (Verona, 1739).
2. G C Zanotti, Vita di Eustachio Manfredi (Volpe, 1745).

Articles:

1. U Baldini, Eustachio Manfredi, in Dizionario Biografico degli Italiani 68 (2007).
2. H Bédaride, Eustachio Manfredi, in Études italiennes 1928-1929 (Paris, 1930), 75-124.
3. P Dore, Origine e funzione dell'Istituto e della Accademia delle scienze di Bologna, L'archiginnasio 35 (1940), 201; 206.
4. S Giuntini, Il carteggio fra i Cassini ed E Manfredi, Boll. di storia delle scienze matematiche XXI (2) (2001), 7-180.
5. I Magnani Campanacci, La cultura extraccademica: le Manfredi e le Zanotti, in Alma Mater studiorum. La presenza femminile dal XVIII al XX secolo (Bologna 1988), 39-67.
6. B Maier, Manfredi, Eustachio, in Vittore Branca, Dizionario critico della letteratura italiana 2 (UTET, Torino, 1973), 480-484.