Francesco Fontana and his 'astronomical' Telescope
📝 Abstract
In the late 1620s the Neapolitan telescope maker Francesco Fontana was the first to observe the sky using a telescope with two convex lenses, which he had manufactured himself. Fontana succeeded in drawing the most accurate maps of the Moon’s surface of his time, which were to become popular through a number of publications spread all over Europe but without acknowledging the author. At the end of 1645, in a state of declining health and pressed by the need to defend his authorship, Fontana carried out an intense observational campaign, whose results he hurriedly collected in his Novae Coelestium Terrestriumque rerum Observationis (1646), the only book he left to posterity. Fontana observed the Moon’s main craters, as the crater Tycho which he named Fons Major, their radial patterns and the change in their positions due to the Moon’s motions. He observed the gibbosity of Mars at quadrature and, together with the Jesuit G.B. Zupus, he described the phases of Mercury. Fontana observed the two - and occasionally three - major bands of Jupiter, and inferred the rotation movement of the major planets Mars, Jupiter and Saturn, arguing that they could not be attached to an Aristotelian sky. He came close to revealing the ring structure of Saturn. He also suggested the presence of additional moons around Jupiter, Venus and Saturn, which prompted a debate that lasted more than a hundred years. In several places of his book Fontana repeatedly claimed to have conceived the first positive eyepiece in 1608, providing a declaration by Zupus to have used his telescope since 1614. This declaration is still the oldest record mentioning such a device. We finally suggest that the telescopes depicted in the two Allegory of Sight by J. Brueghel the Elder belonging to Albert VII might have been made by Fontana, and that he might have inspired the Sight by Jusepe Ribera (c. 1616).
💡 Analysis
In the late 1620s the Neapolitan telescope maker Francesco Fontana was the first to observe the sky using a telescope with two convex lenses, which he had manufactured himself. Fontana succeeded in drawing the most accurate maps of the Moon’s surface of his time, which were to become popular through a number of publications spread all over Europe but without acknowledging the author. At the end of 1645, in a state of declining health and pressed by the need to defend his authorship, Fontana carried out an intense observational campaign, whose results he hurriedly collected in his Novae Coelestium Terrestriumque rerum Observationis (1646), the only book he left to posterity. Fontana observed the Moon’s main craters, as the crater Tycho which he named Fons Major, their radial patterns and the change in their positions due to the Moon’s motions. He observed the gibbosity of Mars at quadrature and, together with the Jesuit G.B. Zupus, he described the phases of Mercury. Fontana observed the two - and occasionally three - major bands of Jupiter, and inferred the rotation movement of the major planets Mars, Jupiter and Saturn, arguing that they could not be attached to an Aristotelian sky. He came close to revealing the ring structure of Saturn. He also suggested the presence of additional moons around Jupiter, Venus and Saturn, which prompted a debate that lasted more than a hundred years. In several places of his book Fontana repeatedly claimed to have conceived the first positive eyepiece in 1608, providing a declaration by Zupus to have used his telescope since 1614. This declaration is still the oldest record mentioning such a device. We finally suggest that the telescopes depicted in the two Allegory of Sight by J. Brueghel the Elder belonging to Albert VII might have been made by Fontana, and that he might have inspired the Sight by Jusepe Ribera (c. 1616).
📄 Content
Francesco Fontana and his astronomical Telescope
Paolo Molaro INAF-OATs Via G.B. Tiepolo 11, I 34143, Trieste, Italy
Accepted 21 March 2017 Journal of Astronomical History and Heritage Abstract
In the late 1620s the Neapolitan telescope-maker Francesco Fontana was the first to observe the sky using a
telescope with two convex lenses, which he had manufactured himself. Fontana succeeded in drawing the
most accurate maps of the Moon’s surface of his time , which were to become popular through a number of
publications spread all over Europe but without acknowledging the author. At the end of 1645, in a state of
declining health and pressed by the need to defend his authorship, Fontana carried out an intense
observational campaign, whose results he hurriedly collected in his Novae Coelestium Terrestriumque
rerum Observationis (1646), the only book he left to posterity. Fontana observed the Moon’s main craters, as
the crater Tycho which he named Fons Major, their radial patterns and the change in their positions due to
the Moon’s motions. He observed the gibbosity of Mars at quadrature and, together with the Jesuit Giovanni
Battista Zupus, he described the phases of Mercury. Fontana observed the two - and occasionally three -
major bands of Jupiter, and inferred the rotation movement of the major planets Mars, Jupiter and Saturn,
arguing that they could not be attached to an Aristotelian sky. He came close to revealing the ring structure
of Saturn. He also suggested the presence of additional moons around Jupiter, Venus and Saturn, which
prompted a debate that lasted more than a hundred years. In several places of his book Fontana repeatedly
claimed to have conceived the first positive eyepiece in 1608, providing a declaration by Zupus to have
used his telescope since 1614. This declaration is still the oldest record mentioning such a device. We finally
suggest that the telescopes depicted in the two paintings Allegory of Sight and Allegory of Sight and Smell by
J. Brueghel the Elder belonging to Albert VII might have been made by Fontana, and that he might have
inspired the Allegory of Sight by Jusepe Ribera (c. 1616).
Introduction
The scarce information we have on Francesco Fontana is given by his contemporary Lorenzo Crasso,
who in 1666 dedicated a book to the outstanding people of his time and counted Fontana among them. From
Crasso’s short biographical notes we learned that Fontana was born in Naples sometime between 1580 and
1590 and that at the age of 20 graduated in Theology and Law obtaining his Doctorate at the University of
Naples Federico II. However, he never practiced in that profession and, following a vocation he had shown
ever since his childhood, he self-taught mathematical sciences and devoted himself to grinding lenses.
Crasso reported that Fontana used to say he preferred the truth of science to that of the Forum [1]. At the
death of Giovan Battista Della Porta, considered by Fontana as the inventor of the telescope, he made several
but all unsuccessful attempts to obtain Della Porta’s instruments. In Naples he was close to Camillo Gloriosi,
correspondent and, in 1610, successor of Galileo at Padua University, and with the Lyncean Fabio
Colonna who commissioned him microscopic observations in 1625. Nevertheless, Fontana was also close to
the Neapolitan Jesuits, who were frequently opposed to the Lynceans, in particular with fathers Girolamo
Sersale, Giovan Batista Zupi and Giovan Giacomo Staserio.
Fontana was a fine craftsman and never needed to do something else for a living. His telescopes reached
the courts interested in scientific and military developments all over Europe. The quality of his lenses was so
high that in 1638 Fulgenzio Micanzio, in a letter to Galileo, wrote: ‘Continual working on and construction
of telescopes is said to have reached such unusual qualities that in matters of the heavens he is a miracle‘
[2]. To advertise his telescopes, Fontana used to send maps of the Moon and news of other discoveries he
had made by observing the sky from the roof of his house in Naples: having manufactured for himself two of
enormous length and fitted on a wooden support on the top of his house, with which observing constantly
the planets, formed the Book entitled Novae Observationes caelestium terrestriumque rerum, which he gave
to light in 1646 (Crasso) [3].
The ‘Novae Coelestium, Terrestriumque rerum observationes, et fortasse hactenus non vulgate a
Francisco Fontana specillis a se inventis, et ad summam perfectionem perductis, editae” (1646) is the only
work he published, though Crasso mentioned a treaty, “On Fortifications”, which has never been found. In
1656 Fontana died from plague along with all his numerous family, and all his mastery was lost.
The work of Fontana received little attention, if not open opposition, of scholars and scientif
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