Brunelleschi’s Dome

Brunelleschi's Rome Ross King Review

„Brunelleschi’s Dome – How a Renaissance Genius Reinvented Architecture“ by Ross King. Published by Penguin Books, 2001.

Brunelleschi's Dome by Ross King

We mounted the dome March 2013, shortly after opening time. We decided to get up early to beat the crowds. Good decision, because upon descending we had to stop and wait for people now climbing up. I suppose there might have been more than a 100 people each way perhaps 70 kgs in average, adding additional 7 tons to the existing 37.000 tons of weight of the dome itself! This additional weight onto the 717 year Santa Maria del Fiore (its construction began in the year of 1296) doesn’t however seem to in anyway affect the monumental building. Nor has this strong construction been effected by minor earthquakes and wear and tear over the years. The humongous Dome seems to violate the laws of nature at first glance by its size and proportion, so that no one visiting the cathedral can help to wonder, how this marvelous piece of architecture came into being. This world-record sized Dome was constructed in a record period of 15 years (1421-1436), in a self sustaining manner meaning image in that it was neither build using a wooden scaffold nor was it filled with dirt to carry the bricks, so when you now look up at the dome´s 30 degree bend turning from vertical to the horizontal, the question becomes how did Brunelleschi dare to risk the life of all the workers involved in laying down the 37.000 tons of bricks, that constitutes the final makeup of the double dome. Ross King has authored a book, that not only provides a thorough answer that uncovering several ‘mysteries’ surrounding it´s construction, but he also unveils a breathtaking history of the life of Florence in that time and age in which the golden renaissance came into being. So it suffices to say in this introduction, this book provides for wonderful background reading, if you are like we were ̶ making a visit to this Mecca of manmade beauty and ingenuity. 

Brunelleschi, today sitting and admiring his own work

In 1367 only the foundation of the cathedral had been build, and a discussion had broken out to question its completion. How should it look?. In the gothic architecture of the time, flying buttresses - sort of a outside skeleton, was used to help carry the weight of the vault and prevent it from collapsing. Just the think of the leaning tower in Pisa, and you know what challenges the constructors of major buildings were faced with more 6-700 years ago. Neri di Fioravanti, the principal master mason in Florence, suggested that a solution could be found, were a Dome is erected, one which is self supporting, with the help of a series of stone and wooden rings, that would create a weight-lock, preventing the Dome from collapsing towards the outside (like on a barrel) and channeling the stress of the weight first sideways to the pillar point and then downwards all the way to the ground. This non-supported solution was then decided upon, but it would take more than 50 years before someone would come around, one with the faintest idea, how the problem of the actual construction of a record 43,74 meters, 143 feet and 6 inches self-supporting Dome could be solved. That someone was named Filipo Brunelleschi (1377 – April 15, 1446).

Brunelleschis Dome

 The biggest existing Dome at  time was the Pantheon, build by Hadrian in the Roman Empire. The thickness of its walls goes from more than 7 meters, 23 feet at its base wall narrow down to about 60 cm, (2 feet). Apparently primitively the way it had been constructed, was by filling it up with dirt and simply laying the roof on top, remove the dirt, and the Dome would now be able to carry itself (though supposedly the Pantheon today has cracks in its walls.) Someone had made the suggestion that this could be done for the Santa Maria Del Fiore as well, and by putting coins in the dirt, people would be motivated to also remove the dirt again, since this was not the age of slavery was the case of the Roman Empire. This was scrapped and the normal construction method of building a wooden scaffolding, was scrapped as well, due to the low availability of wood in Tuscany.  The way to go ahead, was self-sustaining construction-method, where layer after layer wood form their own "barrel rings" which would counter the force of gravitation and lead the force the weight around and down in such a controlled way, that the workers could stand on top of each constructed layer, without risking their life's. As anyone will observe when looking at the dome, is the 30° degree tilt toward the horizontal at the height of 17.4 meters, 57 feet above the drum or base wall. At this point you encounter the "angle of sliding", but the tilt will increase on the way up till it reaches a 60 ° degree tilt. How did Brunelleschi counter and overcome the "angle of sliding"?

Florence from above

This question gets thoroughly answered in Ross Kings book, and only due to a conglomeration of different new construction methods, discovered and developed by Brunelleschi, does he dare risk the life of the many workers involved. One of these Method is visible to naked eye, when ascending up through the middle of the double dome (the construction of the thinner outer "roof-dome" is also covered quite well in the book) is the famous herringbone brick pattern (see pic), which was crucial for allowing the bricks to be laid with a tilt. It's a bit like bookend clamps that prevents the books from falling to the side. Another fascinating crucial aspect of Domes construction is the Ox driven hoist, the template for the modern crane, which latter a certain Leonardo da Vinci studied and drew.

Herringbonepattern

Was this whole in the Herringbone-pattern removed to reduce weight?

tools displayed, used for the construction

The book is so full of interesting anecdotes, especially around lifelong the strife between Filipo Brunelleschi and Ghiberti, as a result one could not only call Ross King a modern but truthful Vasari, but it also serves as a useful biography to the life of Filipo Brunelleschi, who again himself was a fore riding figure in terms of the development of the Renaissance Men. He was the goldsmith turned architect, who did bronze-sculpturing, developed the science of perspective in painting, and created new technologies like the lifting technology and the gearing of the crane and therefore this book provides a lot of insight, into the time and age that came to define the Florentine Renaissance movement the most.

At the drum. A sence of the inside span of the dome. Notice the image from dante Inferno,  a  with a trifork.