It was a fabulous machine. It still is. Covered in glittering gold leaf, taller than its maker, the intricate nest of wheels within wheels, contained inside a large sphere, sits, incongruously, on a base composed of four golden mermaids, writes Anne MacLennan.
The great "universal machine of the world" was made by Antonia Santucci for Ferdinando I de Medici (1549-1609). A handle placed on the axis which goes through the sphere and through the earth no longer turns. So, unlike Ferdinando, we can't see the motions of the stars and planets predicted by the Aristotelian-Ptolemaic system.
The basis of the Ptolemaic system was the notion that, in an earth-centred universe, heavenly objects must move in perfect circles, simply because circles are perfect. Ptolemy's science may have been flawed, but the beauty and complexity of his ideas live on in the universal machine.
This wonderful, vulgar machine is now housed in the Instituto e Museo di Storia della Scienza, in Florence.
Dismissed by most guidebooks in a single paragraph, one of the world's most significant science museums is just around the corner from that favourite of the guidebooks, the Uffizi.
While the Uffizi is home to masterpieces by Botticelli, Michelangelo and Leonardo, the science museum is home to two telescopes used by Galileo. Born in Pisa in 1564, the year Michelangelo died, Galileo was to use telescopes to gather evidence for the Copernician model of planetary motion (thereby helping to discredit the principle behind the great universal machine).
Copernicus himself did not carry out experiments or test his ideas. He believed his idea of the universe was better than the Ptolemaic version, not because it had been shown to work, but because it was more elegant.
By discovering four planets in orbit around Jupiter, which was itself clearly in motion around something, Gallileo showed that it was possible for the Earth's moon to stay in orbit around the earth even if the earth was moving. The unassuming objective lens (now cracked) of the telescope he used to make this observation in January 1610 is on view, housed in an ornate ivory case.
Nearby are two complete telescopes made in his workshop: one is made of wood, covered in leather, with gold embossing, while the other, also wooden, was covered with paper. Measuring 980 mm and 1360 mm respectively, they were clearly much used and much loved.
But the strangest exhibit in the room dedicated to Galilean instruments is contained in a glass egg, with a gold surround. The middle finger of Galileo's right hand was embalmed and has been transformed into a sort of sacred relic, pointing triumphantly upwards.
The motto of the Accademia del Cimento (the Academy of Experiment) was "testing and testing again". It was founded in Florence in 1657 by two of Galileo's former pupils, Evangelista Torricelli and Vincenzo Viviana, under the patronage of the Grand Duke Ferdinando II and his brother Prince Leopold. The foundation of scientific academies around this time was in itself a significant landmark in the history of science.
In the room dedicated to the Accademio del Cimento, there are beautiful long-stemmed, spiral, and so-called lazy glass thermometers. These delicate instruments were produced in the small furnace in the Boboli Gardens, situated on the other side of the River Arno. The thermometers worked slowly. They contained small balls of sealed glass soaked in alcohol. The volume of alcohol varied with the heat applied, causing the balls to rise and fall.
The Accademia only lasted for ten years but it made important contributions to the measurement of the velocity of sound, the physics of changes of state, and to astronomy as well as to thermometry.
Walking through mechanical clocks, mathematical instruments, pneumatic and hydrostatic equipment, one comes to a truly horrible exhibition. The gore of the biological sciences is manifest in a series of anatomical waxes, dating from the 18th century. These show the various positions in which the foetus may present in birth and the instruments that were used to aid delivery.
The waxes were used for teaching medicine and obstetrics to midwives and student surgeons in Florentine hospitals at the end of the 18th century.
Each wax abdomen is open to show the position of the baby but it is the cut-off leg stumps, with their realistic representations of muscle, blood and bone, that truly repel.
In the next room, art once again meets science, this time in a manner that is easier on the eye. A set of elegant pharmaceutical jars from the hospital of Santa Maria Nuovo in Florence contained ingredients such as incenso, arnica, carbone animale and sangue di drago.
The last room open to the public contains weights and measures. While we in Ireland tend to think of the metre as a new unit of measurement, replacing the yard, it was adopted in 1791, at the end of the French Revolution. The use of the metric system spread progressively until it was universally accepted.
There are 19th century samples of the metre in steel on view, as well as a curious balance used to weigh jockeys and some small suspension balances used by goldsmiths and jewellers.
The Instituto e Museo di Storia della Scienza, which is housed in one of the oldest buildings in the city, is at Piazza dei Guidici, Florence (www.imss.fi.it). Admission €6.50.
While the museum provides a beautifully produced explanatory leaflet for each visitor, there are also larger guidebooks, with plenty of detail (and in various languages), which the visitor can borrow for the duration of her or his visit.
There are some 5,000 objects contained in the museum, of which 1,500 are on permanent exhibition in 21 rooms open to the public.
These provide eloquent testimony to the promotion of scientific research by the Medici dynasty (15th to the 18th century) and, subsequently, by the Grand Dukes of Lorraine (18th and 19th century).