The astronomical clock of Mantua

Piazza Erbe today is in the center of Mantua, but once upon a time it belonged to the very first suburb of the virgilian city, whose oldest nucleus was located where Piazza Sordello is located. Its beauty is largely due to buildings raised or restored over the centuries, from the Middle Ages to the Renaissance and beyond. In particular, the Tower of the Clock was built in the year 1473 as a completion of the Palace of the Reason, where politics and justice were administered in the era before the Gonzaga family took power over Mantua. The author of the tower is Luca Fancelli, the Tuscan of Settignano who decided so much about the view of Mantua, carrying out the indications of Leon Battista Alberti.

However, the imposing statue of the Immaculate Virgin Mary, the source of the Moon, the balcony and the upper crown, were added later. The XV century appearance of the tower and the square probably can be derived from an ornate wooden artwork of the Cathedral of Cremona, created by Giacomo Maria da Piadena called il Platina. Here stands out the stylized figure of the astronomical clock, invention of the genius of Bartolomeo Manfredi. He was first a mathematician, John’s of the Clock son.

Astronomical clocks had spread mainly in Northern Europe already during the XIV century. In Italy, the oldest is certainly located in Padua, which today overlooks Piazza dei Signori but which came, at least as a conception, from the lost Reggia Carrarese. The astronomical clock of Mantua is the second built in Italy in order of time, and the first one that today we can see in the site for which it was conceived. Luckily the construction of the Clock is documented by a letter from Manfredi and illustrated by a text printed by Pietro Adamo de 'Micheli.

So we have a precious testimony of the original purposes of the mechanism, of its way of pointing out the astrological time and also of the astronomical culture that in the Renaissance was so influent.
Manfredi's clock has at least eight effects. Here we list them synthetically. 

First Effect: let the people know how many hours have passed since sunset.Second effect: to show the zodiacal sign in which the sun is.
Third Effect: to show if the moon is new or full.
Fourth effect: to make possible the calculation of the Ascendant; this is an astrological technical detail of the highest importance to infer the influence of the stars at an exact moment.

The crescent moon is on the top of her head, and on the side she has a gentle fawn. Next to the left hand is indicated the moon phase; from the same hand there is a golden ray that indicates a sign of the Zodiac, where the Moon is; the right hand, armed with a falcon, indicates the day of the lunar cycle.
Latona is surrounded by a first record of twenty-nine lunar days, in Arabic numerals, and a second record of twelve zodiac signs. Each sign is then characterized by six shields, which divide it 5 degrees to 5 degrees.

A hand marked by the Sun symbol indicates the zodiac sign of the day.
We can see also twenty-four painted bands, twelve white and twelve black, corresponding to the daytime and night time.
In the middle there is a blue semicircle, fixed to the zodiac from the first degree of Libra to the last of the Pisces, to represent the celestial equator. Finally, the exterior part of the dial is distinguished by the twenty-four hours of the day, painted with latin letters, which naturally correspond to vulgar hours, indicated by another appropriate hand.

In December 1473, in Mantua was printed a little book in which the mantuan Pietro Adamo de 'Micheli described the functions, the purpose and the symbolism of the astronomical clock. He has been called a singular character indeed. He studied law in Ferrara but was also largely self-taught. As an author, we know only this text, which offers him the opportunity to demonstrate his lyric quality and his undoubted scientific and technical knowledge.
Pietro Adamo was also the first Mantua publisher, leading to the printing in 1472 a Tractatus Maleficiorum and later the Decameron.

It was certainly facilitated by a distant relationship with the Gonzaga family, which allowed him to have a good favor for his activities.
"Here Piero Adamo depicts all the effects & demonstration of this admirable & singular work called clock."
The treatise on the clock is further illustrated by two embossed china designs, which probably derive from another mutilated little book. The most interesting is the quadrant, in which stands the central goddess, accompanied by the fawn and the crescent moon.

Inside the tower, we can admire the original metal discs of the clock. We can see the larger one, the zodiacal, and the one in which appears the figures corresponding to the division on lunar days.
The disk on which the zodiac signs are located in is itself an artwork. 

They are engraved with great skill by an unknown master, who has probably put all possible care in illustrating the seasonal principles in which the time of the year was divided. From the distant past, through Babylon and Greece, faith in the signs comes to the Middle Ages and the Renaissance, remaining in the midst of heated debates, basically intact.

In 1989, thanks to the Municipality of Mantua, the ancient clock was restored by the precious work of Alberto Gorla, the watchmaker of Rivarolo Mantovano. The mechanism was rebuilt and made fully operational. Gorla himself describes it to us as a complex with a length of 2.80 meters, a width of 2.40 and a height of 1.90.
Following his own words: "The machinery is made up of two trains: the time train and the ringer train, that are placed one next to the other and also near to the astronomical machine."
The watchmaker also says that the driving force is made up of weights that give to the clock an autonomy of 48 hours.

But the charging system is automatic. If the watch stops, you must recharge it and record it manually with a manual maneuver that records the exact time of day, month, zodiac, night length, moon phases, and the lunar age expressed in lunar days.
Thus, since 1989 the ancient artifact is again efficient and marks in front of the eyes of the mantovans and visitors the time of the day and the astral time, bringing us almost perfectly at the time of the Renaissance.

Here we can see the image of the ancient clock, as it appears in a reprint from 1547 Pietro Adamo de Micheli’s work, titled "Declaration of the Clockwork of Mantua", kept at the Virgilian Municipal Library and illustrated by the printer Giacomo Ruffinelli.
In addition to presenting a detailed description of the dial, the printing shows us that the whole process of time seems to be supported by Hercules, who here takes on almost the task of Atlas, giving the burden of raising with his sturdy arms the sky of the zodiac, the figures that indicate the flow of hours and the goddess 

Diana from which the indication of the same.
On the sides of the mythical character we can see also two men dressed in the Oriental way, differently identified: certainly two wise men, one of whom in all likelihood is Ptolemy.
The work of Pietro Adamo is accompanied by a sonnet kept in the National Library of Florence, which reminds the vanity of human gestures in the face of the inexorable proceeding of divine will. Here are some of his verses:"But God laughs, and there he divides
honors, treasures and kingdoms,
and cause to fail our wills and projects.
Cesar kept the whole world in one hand,
and then Cassio and Bruto broke all his dreams
and all the efforts and the thoughts where vain. "