Person: Grimaldi, Francesco Maria
Francesco Grimaldi was an Italian Jesuit priest, mathematician and physicist who worked in mechanics, philosophy, astronomy and optics.
Mathematical Profile (Excerpt):
- Francesco was the fourth of his parents six sons, five of whom survived.
- We do not know all the places where Grimaldi studied, in particular we are unsure where he spent the two years 1632-34 although it was most likely in Novellara.
- The Jesuits ran three educational establishments in Parma, the university, a college for educating the sons of the nobility, and a Jesuit College, established around 1600, which Grimaldi attended.
- Grimaldi was taught by Giovanni Battista Riccioli in Parma in 1635 and both had moved to Bologna at the same time in 1636.
- However, it was when Grimaldi returned to Bologna and was teaching there in 1640 that he began assisting Riccioli with experiments.
- Grimaldi, working under instruction from Riccioli, dropped weights from the Asinelli tower and timed their fall using a pendulum.
- Riccioli was hoping that the experiments conducted by Grimaldi would refute Galileo's theories, which in some sense they did.
- First, Grimaldi and Riccioli calibrated a pendulum by getting it to swing for 24 hours (measured by the star Arcturus crossing the meridian line).
- Then Grimaldi dropped balls of wood and of lead from various heights from the Asinelli tower.
- The discrepancy between the experiment and Galileo's claim that they reached the bottom simultaneously was so great that Grimaldi supposed that Galileo must have known about it, but suppressed his knowledge in order to secure a proposition dearer to him than truth.
- Over the next few years Grimaldi continued studying but also worked, particularly on astronomical investigations, with Riccioli.
- Grimaldi was well prepared to teach all branches of mathematics: geometry, optics, gnomonics, statics, geography, astronomy and celestial mechanics.
- Grimaldi was ordained a priest on 1 May 1651.
- In the same year Riccioli published Almagestum novum Ⓣ(A new 'Almagest') in which he credited Grimaldi with being the source of over 40 different experiments.
- Grimaldi and Riccioli's astronomical observations had been made in an observatory set up at the College of Santa Lucia in Bologna.
- In the Almagestum novum Riccioli thanks the "diligent, prudent, and faithful" Grimaldi.
- He says that he was too old to conduct the required late-night observations himself, so he had to rely on his young collaborator Grimaldi.
- Another project on which Grimaldi worked was a survey, using triangulation, to determine a meridian line for Bologna.
- Grimaldi did a considerable amount of observing and the data from his observations of stars was published in Riccioli's Astronomia Reformata Ⓣ(Astronomy reformed) (1665).
- Now although we have given quite a lot of information about Grimaldi's work, everything we have mentioned so far was published in works by Riccioli.
- Grimaldi has no works published under his own name during his lifetime.
- The work is an attempt by Grimaldi to determine whether light is a substance or whether it is a quality of another substance.
- Grimaldi makes it clear that his own view is that light is not a substance and he believes that the arguments in the second book make it probable that light is a quality.
- Book 1 begins with a description of Grimaldi's most famous discovery, namely the diffraction of light.
- The name diffraction was chosen by Grimaldi because the effect reminded him of how a flowing fluid splits apart when a thin stick is placed in its path - the Latin diffractio means to "break apart".
- Next Grimaldi treated reflection, refraction, and the propagation of light.
- Perhaps surprisingly, Grimaldi's treatise was little read but his important results on diffraction were made widely known by others.
- Honoré Fabri's Dialogi physici sex quorum primum est de Lumine Ⓣ(Six dialogues on physics: the first is on Light) has as its first dialogue 96 pages containing the description of Grimaldi's experiments.
- Fabri, however, did not believe Grimaldi's "explanation" of the results obtained and attempted to give his own interpretation.
- It is worth noting that Grimaldi's attempt to explain diffraction was incorrect, as was the attempt of every scientist until Joseph von Fraunhofer (1787-1826) in the 19th century.
Born 2 April 1618, Bologna, Papal States (now Italy). Died 28 December 1663, Bologna, Papal States (now Italy).
View full biography at MacTutor
Tags relevant for this person:
Astronomy, Origin Italy
Thank you to the contributors under CC BY-SA 4.0! 
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- non-Github:
- @J-J-O'Connor
- @E-F-Robertson
References
Adapted from other CC BY-SA 4.0 Sources:
- O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive
