QUIZ – Solution
It is the magnetic clock
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A Timeline |
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This timeline traces the origins of Athanasius Kircher's magnetic clock from theoretical and practical studies of magnetism in the early seventeenth century. |
View
an interactive map
of the transmission of information about the magnetic clock |
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1600 William
Gilbert publishes De Magnete (On the Magnet), in which he puts forward
the hypothesis
that the Earth is a great magnet. Experiments carried out with a
"terrella", or small spherical magnet, convince him that the earth
rotates around its poles because of terrestrial magnetism. 1609 Johannes
Kepler publishes his Astronomia Nova (New Astronomy), in which he puts
forward the hypothesis that the planets were moved by a magnetic force. 1618-21 Kepler
publishes his Epitome astronomiae Copernicanae (Epitome of Copernican
Astronomy), which further develops his hypothesis that the planets are
carried around the sun by a magnetic force emanating from a rotating
sun. 1632 Galileo
publishes his Dialogo
sopra i due Massimi Sistemi del Mondo (Dialogue on the Two Chief
World Systems). He includes an argument against Gilbert's assertion that a
spherical magnet will rotate every twenty four hours. 1633, 15 June:
Godefrid Wendelin writes a letter from Brussels to the Minim scholar Marin
Mersenne in Paris to inform him of a magnetic clock
invented by a Jesuit professor in Liège, Fr. Francis
Line. The clock contains a wax globe that appears to rotate in imitation of
the sun's motion. 1633 22 June.
Galileo is sentenced by the Inquisition of being "vehemently suspected
of heresy" for teaching the Copernican doctrine in his Dialogo
and is forced to make a public abjuration in the Dominican Church of Santa
Maria sopra Minerva in Rome. 1633-4 Line's magnetic clock
comes to the attention of the Papal Nuncio of Cologne, Monsignor Pierluigi
Caraffa. Caraffa has the clock brought to his home, where he observes it for
several days and finds it to keep good time. His Jesuit confessor, Father Sylvester
Pietrasancta, publishes a description and illustration of Line's clock
in a book of emblems published in Antwerp, Silvestro Pietrasancta's De Symbolis Heroicis. 1634 December:
Monsignor Caraffa and his confessor travel to Aix-en-Provence,
where they visit Nicholas Claude Fabri de Peiresc at his home, the Château de
Beaugencier. Peiresc is shown the description of Line's magnetic clock given
in Pietrasancta's work. 1634, December
18: Peter
Paul Rubens, responsible for designing the frontispiece to
Pietrasancta's book, writes to Peiresc to say that he has "talked with
men of ingenuity who have seen and operated it with ease, and have the
greatest admiration for it". Rubens even offers to ride from his home in
Antwerp to Liege to visit Line and obtain more details of the clock. 1635, 1 April:
Peiresc writes from Aix to Galileo (under house-arrest in Arcetri, near Florence),
describing the "hydraulic clock" in enthusiastic terms. He believes
that the instrument could provide a demonstration of the Copernican theory,
writing that "it seems to be a proof and testimony that has fallen from
heaven into the hands of a Jesuit father, rather than those of somebody of
another calling, to leave no room for suspicion against the testimony of the
Father who invented it or the other who published it, to demonstrate the
error of those who find such repugnance in the Copernican doctrine and in
that which Your Lordship proposed about it as a problematic joke (i.e.
Galileo's Dialogo)". According to Peiresc, Caraffa had examined
the clock in his own home for several days and found it to be very
accurate. 1635, 17 April:
Peiresc writes again to Galileo informing him that he is attempting to use the
magnetic clock in his efforts to convince Cardinal Francesco Barberini, the
papal nephew, to have the charges against Galileo reduced, and to free him
from imprisonment. 1635, 12 May:
Galileo writes a letter to
Peiresc, explaining that he had made a similar invention many years
before, and suggesting that the base of Linus's device contained a hidden
magnetic clock, whichthat moved another magnet hidden in the hollow copper
sphere. The sphere, in Galileo's version, was suspended at the boundary
between salt water and fresh water due to its intermediate specific
gravity. 1635, 18 June:
Peiresc writes to Gassendi to say that he has heard more information about
the machine from an eyewitness, Dormalius, who claims that the inner sphere
was originally made of wax, but that Linus then chose a hollow copper globe.
The fact that the globe moved back to its position when displaced
horizontally led Peiresc to be very suspicious that a hidden mechanism, like
that described by Galileo, was responsible for the rotation of the
globe. 1640: 8 March:
Responding to hisKircher's request for magnetic observations, the Jesuit
Lorenz Mattenkloth writes to Athanasius Kircher from Münster to ask him if he
has heard about Line's magnetic clock, and if he has an explanation for its
mechanism. On the same day Grégoire de Saint-Vincent also writes to Kircher
telling him about the invention of the machine by "some English
Father" 1641: Athanasius
Kircher publishes his Magnes, sive de arte magnetica in Rome. The work
includes the first published description and illustration of the secret
mechanism of the magnetic clock, and a lengthy attack on the magnetic
arguments in favour of Copernicanism put forward by Gilbert and Kepler. |
Website created by
Michael John Gorman, April 2001.
Comments, questions or suggestions to mgorman@stanford.edu
http://shl.stanford.edu/Eyes/kircher/intro.html
http://shl.stanford.edu/Eyes/kircher/timeline.html
http://shl.stanford.edu/research/artificial_eyes.html
