The attempt to look at Alberti’s architecture beyond its material and theoretical limits is the search for an area of activity standing, in some way, between the drawing board and the building site, between the physics and metaphysics.  Alberti attempted to characterise this somewhat mysterious zone by means of a joke in his treatise, De pictura (1435) 

Underlying the painter’s art, he showed, was drawing.  Drawing was equally indispensible to the architect.[1]  Its points and lines, with their power to generate planes and bodies, are, at the same time, the essential objects of the pure geometer, who, of course, deals with no-dimensional points and one-dimensional lines.  Being impossible things, outside of the minds of geometers going about their business of logical demonstration, these objects needed, when they came into the hands of painters and draughtsmen, a corporeal way of manifesting themselves.  Alberti said that he would employ ‘una più grassa Minerva.’[2]  The goddess of wisdom, usually as bony as an axiom, would, for Alberti, put on a bit of flesh.  Whereas Hamlet would regret his imprisonment in matter and plead for annihilation as his means of escape, Alberti shrugged at the histrionics of Platonism.  The draughtsman would mark the sheet with one-dimensional points and two-dimensional lines (at the least).  The performance would be Falstaffian.  Alberti was interested in the mathematical nature of things and in practical mathematical tools for making and describing things.[3]

The term ‘mapping’ is used here as a sort of net in which to gather a variety of devices and procedures that were developed in the first half of the fifteenth century for establishing the mathematical nature of things, namely their quantity, quality and place.  They comprise a family whose relations are sometimes close and sometimes distant, even mysterious.  The circumstances of their invention – born out of necessity or else accompanied by the cry of Eureka – and their mathematical nature hold out the possibility of reconstructing a part of the rational life of their inventors.

The architectural undertaking that most had called for new devices to see it through to success was the dome of Florence Cathedral.(fig)  Alberti is to be pictured as the ruminative observer of the scene, and the building came to preside, as a golden thread in his thought.  The project had acted almost like a lively research laboratory’s common room – except that the conversation seems to have been led pretty well exclusively by the research professor, Filippo Brunelleschi, the cupola’s ‘inventor et gubernator’.[4]  Before he had conceived the solution to the problem of vaulting the octagon at the east end of the building, it had become clear that the skills and methods of the artisan tradition were inadequate to the task.  The identification and analysis of problems and the invention of new solutions became essential to the building process.[5]  When Brunelleschi succeeded in persuading the officials of the Cathedral Works that the dome could be built without centering, he presented a completed concept; but he had not reached a stage where the execution of the work would be automatic.[6]  Machinery – material and rational – remained to be developed and then applied.

It is a curiosity of the dome project that it –observably- grew.  Whereas, in conventional building, a centering is a pre-existing form or external rule dictating the assembly of parts, the absence of a centering in this case required that the rising dome contain or possess a regulatory principle that was coincident with the material and with the moments in time through which the construction would pass.  That principle in the natural world is of organic growth.  There may be a point of arrival in the future; but, as time-lapse photography makes clear to us, the observation of growth prompts an awareness of events in the present tense, and the end is, in the meantime, concealed.   In the case of the dome, the spectacle must have been astounding.  It marched without crutches to a destination that seemed unknown.

However, the growth only looked like a process of Nature: the structure was a work of art in fact, and the principle of its growth had to contain a teleology.  The dome needed to rise on specific trajectories, to arrive at another, smaller octagon, mathematically precise, and just twice as high as the span of the space.  There could be no deviation or error.  In other words, the dome could not in fact dispense with a centering.  That centering just had to have, instead of a material actuality as a timber formwork, a rational existence and function – an immaterial reality.  Historians have speculated on the nature of the device or devices that regulated the progress or flight.

In particular, they have conceived various pieces of apparatus involving cords and wires.[7]  The prompting to do so comes partly from the famous drawing, made by Giovanni di Gherardo da Prato, whose accompanying text accuses Brunelleschi of deviating from the arch profile that capomaestri where sworn to follow, and which shows the method for constructing the ‘Quinto Acuto’ or ‘Pointed Fifth’ arch.(fig)[8]  It is a matter of striking arcs; of stretching chords or wires.

Another encouragement to conceive the use of an arc-striking apparatus is Alberti’s instruction, in De re aedificatoria, on how to create domes without centerings.[9]  A rod is pivoted at the centre of the springing plane of the dome, its other end touching and therefore locating all the bricks of the construction, in Antonio Manetti’s account of Brunelleschi’s Ridolfi Chapel in San Jacopo sopr’Arno.[10]

Of course, the dome of Florence Cathedral does not have a single radius, either in plan or in elevation, and so Alberti’s method is not applicable to the case.[11]  Distances of the various parts of the fabric from the axis are multitudinous.  It is therefore necessary to conceive something more complicated than the device described by Manetti and Alberti.  But, in fact, all such devices have the problem that they must be made of material that will either stretch or sag when rigged up beneath the rising dome.  They become mathematically imprecise and therefore incompetent to regulate construction with accuracy.

Another device is documented, however.  It was one which, when properly considered, can be seen to be capable of accurate regulation.  Giovanni Battista Gelli (1498-1563) stated that Brunelleschi had had flattened an area on the bank of the Arno, and there made a 1:1 drawing of the dome.[12]  Gelli was telling a hundred-year-old story that is not otherwise corroborated.  But it has the ring of truth, mostly because – if some tricky reasoning be allowed – so useful would it have been for the project, so much must its non-existence have been an impediment to building.  It is instructive to consider how the drawing may have worked, the problems it solved and the inspiration that it provided.

A first problem that the drawing could have solved might have been very practical.  Lodges could have been set up in the vicinity and component parts of the structure could have been made there, before delivery on site.  As a place of assembly more than manufacture, the building site would have borne some resemblance to that of Solomon’s Temple. The First Book of Kings 6:7 reports, ‘And the house, when it was in building, was built of stone made ready before it was brought thither: so that there was neither hammer nor axe nor any tool of iron heard in the house, while it was in building.’

The drawing would have had a more direct role in regulating the dome-construction mathematically.  An axis is an origin of radii at rising levels.  The axis of the dome is located in relation to the material structure according to mathematical rules both in elevation and plan.  But the radius is not fixed in either plane.  In plan, the length of the radius oscillates as it passes now along the long diameter of the octagon and now along the short.  In elevation, it increases (according to the rule of the Pointed Fifth) as it rises.  Therefore, because such a multitude of radii are present in the dome, cords or wires cannot act the part of radii in a simple and convenient way.[13]  Brunelleschi, in order to regulate the growth of the dome, had to find a way of escaping the magnetic authority of the axis of the dome.

The 1:1 drawing, if the indicative voice may be allowed, enabled him to do this.[14]  It is a copy of the situation of the dome, with the problems of the material world, like gravity (that makes wires sag), removed.  To be useful, it would have to contain all the mathematical facts of the built dome itself: so it is sensible to conceive the drawing as a plan and elevation. There, every mathematical point can easily be located with reference to the axis, and any two points are at a distance that is to recur in the actual dome.  As will be seen, back at the building-site itself, all that survived of the mathematical definition of the form was the point on the pavement where the immaterial axis emerged and rose into thin air, and an orientation of the octagon with regard to some pole, like a point of the compass.  For ease of understanding, though without the insistence that this is just what Brunelleschi did, let there be marked out on the pavement, centred on the axis point, a set of radial lines, as many as may be required.

At the drawing, a point is a certain distance from the line representing the pavement of the octagon; it is a certain distance from the centre, and it has a certain ‘compass’ bearing.   A plumb line and a linear measure are all that are required for the corresponding point to be found in the actual dome.  If a point in the actual structure corresponds with the data for that point generated in the drawing, all is well.  Any distance from one point to another in the drawing, where both refer to points within the material structure can be measured upon the material structure and the accuracy of the building process can be checked.  Except vertically, there need be no measurements taken across the void.  It is not important for present purposes that the drawing can also be used to other ends, like the production of templates.  The prime importance of the drawing is that it allows the location of all points of the structure to be determined with regard to the crucial axis, but without the axis needing to have a functional presence at the building site itself.  There is no need for spiders’ webs and tangles of wires.

This is both obvious and remarkable.  The drawing, which is literally elsewhere from the Cathedral, informed it, and can be said in a certain sense to occupy it.  Or, to put the matter another way, the data can be thought of as inhabiting the present building and, therefore in a ghostly way, to have been there first.  The dome was predicted by ratio. 

The drawing seems to have continued to inspire Brunelleschi, for basically the same mathematical procedure was performed by the Castello.(fig)  The crane that he invented for placing heavy components of the dome, the Castello located their destination in the same way as points on the dome had been verified by plumb line, measure and compass.  The jib revolved, the hook ran out or in along the jib, and the weight could be raised or lowered.  The Castello, then, is attached to an invisible but ineluctable mathematical container – a virtual cylinder – within which any point has three identifiable coordinates, two linear and one radial.

Alberti seems to have understood Brunelleschi’s devices. In his treatise, De statua, he invented for the sculptor three of his own, that seem to have emerged from a meditation upon Brunelleschi’s mathematical definition of the cupola.  The first two were devices for finding the absolute sizes of things.  First was the Exempeda –a ruler with six divisions.  The whole length was taken from the figure to be measured, so that the six feet were relative to the thing rather than absolute. The second were the Normae Mobiles.  There were, in effect, a set of callipers, able to measure everything with solid extension in the thing to be sculpted (Alberti let it be a human figure).  His refinement of what was presumably an omnipresent tool in the sculptor’s workshop was that it provided sizes that could be read off directly in whatever unit of measure the sculptor had chosen.  Callipers took sizes, not measures.  The device consisted of two set-squares confronting one another, their bases aligned.  The vertical elements, measuring the width that was to be known, approach and withdraw as necessary along a slide.  The Normae Mobiles are an inversion of the simple ruler, since they measures where the void stops rather than starts.  Whereas the ordinary ruler, as-it-were adds up the units of extension of a thing until the extension ceases, the Normae Mobiles search for the start of the thing’s extension, at both ends.  Alberti’s concept of finitio, one of the mathematical definers of things in De re aedificatoria, along with numerus (quantity) and collocatio (place) seems to have some association with the action of his Normae Mobiles.[15]  In De statua, Alberti used the callipers to produce his table of sizes of the ideal man.  In other words, insofar as the man’s definition is mathematical, the basis of all proportional relationships is to found in the data supplied by the Normae Mobiles and the Exempeda .  It is important not to over-state the parallel between the devices of Brunelleschi and Alberti, but the Normae Mobiles and Exempeda  – or rather, the table of sizes – does have a certain resemblance to Brunelleschi’s 1:1 drawing.  Both stand aside from the complications of the material case, gathering together all data in mathematical form.

The third device was the Finitorium.[16] It is strikingly similar in its operation to Brunelleschi’s Castello.(fig)  And, as the Castello re-enacts the regulatory procedure of the 1:1 drawing, it is like that too.  The job of the Finitorium is to allow the specification of points on the surface of a statue in an active pose.  So, for example, because he is an orator, the figure raises his hand.  The sculptor wants to replicate the position in space of the orator’s finger-end in the statue that he is making.  Alberti sets a disc, which he called the orizon or horizon, with a calibrated circumference upon the head of the statue.  One end of a calibrated ruler is fixed at its centre, and the other end may rotate.  From the end of the ruler hangs a calibrated plumb line.  The system is the same as Brunelleschi’s crane.  The disc is given the equivalent of a compass setting.  The ruler is rotated until it is vertically above the finger-end of the orator, and a reading is taken from the calibrated circumference of the disc to register the orientation.  The plumb line is then hung from the ruler, touching the finger end.  From the calibrations of the ruler is taken the distance from the centre of the disc (and the axis of the statue) and from the calibrations of the plumb line is calculated the height to which the finger is raised.  The Castello located its loads in the same way.  Indeed, the operator ideally could have been given the orientation and the plane and vertical distances – a purely mathematical set of data- and could have placed the stone.  The Horizon, rule and line navigate the same sort of virtual cylinder that the Castello masters.

Alberti has designed – for the figure that can be disposed in any way in space – a cylindrical matrix allowing any point to be given three coordinates.  Brunelleschi’s 1:1 drawing had done the same thing for the dome.  It seems likely that Alberti took the lesson of Brunelleschi’s inventions, or else – less likely, in view of the great impression that the dome made upon Alberti [17] – they derived their procedures from a common source.[18] Alberti was in the entourage of Pope Eugenius IV, exiled from Rome and housed in the monastery of Santa Maria Novella in Florence, from 1434 until 1436 when, immediately after the dedication of the finished dome, he accompanied the Pope to Bologna.  Eugenius at length returned to Rome, in 1443.  In the years immediately following, Alberti used the Horizon and rotating ruler of his Finitorium in a somewhat different way and to a different purpose.  He produced the data of the Descriptio Urbis Romae.[19]

Alberti supplies to the reader the mathematical means to draw a map of Rome.(fig)  His reader in Paris will make an identical version to his twin in Florence (though they are allowed to differ the scale).  Both prepare a disc on which the map will be drawn.  It is calibrated in a similar way to the Horizon in De statua.[20]  So too is a ruler, one end of which is to be set at the centre of the disc, while the other rotates.  ‘Zero’ on the circumference gives the compass orientation and ‘zero’ on the ruler marks the centre.  Any point on the plane of the disc can be denominated by an orientation and a distance from the centre.  Alberti then supplies these two coordinates (radial and linear) for prominent structures of Rome, seen from the Capitol (point ‘zero’ of the city), in the form of a table.  The calibrations of the disc and ruler correspond with those of the table. A drawing surface will be marked with a centre and the same radial directions of the landmarks.

The locations of Rome’s landmarks in the radial table were easy to establish.  The disc and ruler were simply used as a viewing device positioned at the Capitol itself -probably the tower of the Palazzo dei Senatori.  The other table – of distances of landmarks from the centre – was put together by means that Alberti does not explain.  He probably did something similar to what follows.  He had first to make his calibrated ruler represent a certain number of cubits.  As he says in the text, the distance from the Capitol to the city walls is never more than 6,140 cubits.  He then finds two landmarks that are visible from the Capitol and whose distance apart can be measured on the ground, that is, without estimation.  He registers their radial locations before taking his disc and ruler to one of them, where he registers the radial locations of the Capitol and the third landmark.  The line that passes from the second to the third landmark is of a known length.  Returning to his drawing surface, he maintains the angle on the third landmark and shifts the line until it touches the radial coming from the Capitol, Alberti has one distance and three angles.  He can now calculate the distances of the landmarks from the Capitol.  One of them, equally commanding and perhaps of equal use for map-makers, was to have been the Torre di Niccolo, by the Vatican Palace.  However, it did not reach its intended height.[21]

Any number of maps had been made of Rome before Alberti’s; but they differed from his in that they showed the architectural or pious contents of the city distributed with a rough indication of their orientation to one another. Taddeo di Bartolo’s fresco in the Palazzo Pubblico in Siena, of 1414, is an example of this sort of map.(fig)  Interestingly, Taddeo di Bartolo set the tower of the Palazzo dei Senatori on the vertical bisector of his map, and just a little above the horizontal bisector.  Maps like Taddeo’s were clearly sufficient to their purpose.  Rather as with Portolan maps, one knew in which direction to strike out; but one did not know how far off was one’s goal.  The same sort of clarity about direction but imprecision about distance within picture space marks the sort of perspective that Giotto used.  Alberti’s map, however, stands in relation to the city conceived mathematically, as a set of orientations and distances.  It resembles very much Brunelleschi’s 1:1 drawing in its relation to the dome.  Even as a set of numerical data, it resembles Brunelleschi’s drawing.  What was written upon the scrap of paper that the apprentice received from the surveyor by the Arno and shinned up to the top of the dome with was like a fragment torn from Alberti’s table in Descriptio urbis Romae (minus one coordinate).  Because the subsequent history of map-making has continued very largely to be concerned with scaling down actual distances, it is easy to overlook how novel it was for Alberti’s system to relegate the established motives for map-making in favour of the establishment of things in exclusively mathematical terms.  Once done, other strictly mathematical matrices could be laid on top of the drawing made according to the data.  For example, it would be possible to lay a pavement like that of the costruzione legittima on top, and the map would have grid-references.  Alberti’s map, supplying distances, would have given its first users a wonderful sense of the completeness of their rational understanding.  There would even dawn a sense of the dimension of time as a function of space, for they could now make an estimation of how long it would take to reach their goal.

Alberti’s purpose in making the map – and in the form that he did it – was partly to conduct a conversation with like-minded people on the subject of communication.  As Mario Carpo observes, by providing the map in digital form, Alberti avoided the problem that belongs to the conventional drawing – that the copy’s accuracy depends upon the skill of its maker.[22]  Undeviatingly accurate drawings could be produced anywhere and at any time by persons without skill.  Again, the situation of the dome project was similar.  The data that the apprentice carried demanded no interpretative skill of the masters at either end of the journey.

A further purpose in making the map of Rome is to be connected with its form as a drawing.  It could be an aid to planning.  At ground level, Rome was, famously, a scene of dereliction and confusion.  Alberti’s friend and fellow Papal Abbreviator, Poggio Bracciolini wrote a description in De varietate fortunae (1431-) that is vivid and celebrated: ‘…when I first  … went to Rome, almost nothing was left of that old Rome but an outline or an image, and only the ruins bore witness to its bygone greatness…’[23][put in more] Improvement, which was a pressing need and had been begun by Martin V after his return to the city in 1420 continued under Eugenius IV and Nicholas V.  An obstacle to it was the shere obstructive shambles of the place.  Among the various instruments needed for the task of improvement, to combine with a policy and a programme of actions, was a wider perspective upon the scene than that offered in reality.  An accurate map was required.  In particular, it was needed at an office that had been rescuscitated and empowered by Martin V, that of the magistri viarum.  These officials were sanctioned to clear obstacles to circulation and communication within Rome.  Provided with a map, they could see, at a glance, the implication of the removal or retention of any structure.  Without such an instrument, their determinations were tainted by arbitrariness. 

The use of a device to direct a path irrespective of obstacles is made the clearer where Alberti dealt with tunnelling for water supply in Book X, Chapter 7 of De re aedificatoria.  A modified version of the device is described.  A ten-foot diameter platform is made on the top of the hill to be tunnelled: ‘…is circulus orizon nuncupatur.’  A sighting pole is set at the centre.  A diameter is drawn to align with the water-course as it will enter and exit the tunnel to be cut.  If the tunnel is not to pass under the centre of the orizon,  sightings of the entrance and the exit are taken and the corresponding diameters are drawn.  A line drawn between the corresponding points of each diameter gives the direction of the tunnel.  Alberti concludes the description by saying that he also uses this method for drawing and painting towns and regions: ‘Nos circuli istius adminiculo ad urbium provinciarumque descriptionem annotandam [sp.? Check. Why? Looks right] atque pingendam…”.[24]

Alberti was, of course, much concerned with the restoration of Rome.  His treatise, De re aedificatoria, as well as a book of general information, advice and advocacy, can be considered an attempt to shape the moral, social, formal and historic project.  He presented a version, in 1452, to Nicholas V, the pope who, according to Gianozzo Manetti, his secretary and biographer, put together a systematic and comprehensive five-part programme for the restoration of the city (and especially the Vatican area).[25]  Assuming that he read Alberti’s treatise, a passage in the prologue would have been a strong incentive to Nicholas to make the city fit for the institution of which was head.

Quantum veri auctoritati imperii et nominis Latini contulerit aedificatio, nihil plus dico quam nos ex his bustis et residuis veteris magnificentiae, quae passim videmus, multa historicis credere didicisse, quae alioquin fortasse minus credibilia videbantur.[26]

The fragility of authority and reputation are the clearer to apprehend when the fabric is ruinous.  At the same time, material remains prevent tales from being merely fabulous.

Alberti included in De re aedificatoria an account of the works that he did to stabilise St Peter’s.[27]  It is probably an addendum to the text of 1452.  Others involved in giving shape to the programme would include Poggio Bracciolini who, as has been seen, attempted to identify the causes of the catastrophe for the city – in effect, a diagnosis of its ills, and a pointer to the needful therapy.  It was he who had found the copy of Vitruvius, at St Gall in Switzerland, that Alberti studied and believed needed an up-dating in the form of his own De re aedificatoria.  Flavio Biondo, who dedicated Roma Instraurata to Eugenius in 1444-46, was another member of the group.[28]  Manetti’s extensive account of Nicholas’s plans for Rome suggests that he too took a close interest in the project.  Alberti’s Descriptio urbis Romae should be seen as another contribution to the groundwork that was needed in preparation for the restoration.[29]  As has been seen in De re aedificatoria, Book X Chapter 7, he describes the use of the same mapping device combined with a surveyor’s pole set in the centre to direct tunnelling.[30]  It was evidently possible to draw lines with obstacles in the way.

The pope who exploited Alberti’s map of Rome most assiduously and effectively, or else the succeeding maps that Alberti’s made possible, was Julius II.  However, it is very possible that Julius simply enacted a plan of action that was conceived earlier.[31]  The via Giulia is a straight street, passing all the way from the Lungotevere opposite the Ospedale di Santo Spirito in the Vatican district, to the Ponte Sisto.(fig)  The previous via del Pellegrino took the same route by a meandering path taking in the Campo dei Fiori.  The Ponte Sisto itself connects Trastevere with the fifteenth-century abitato – the part of medieval Rome that snuggles in the bend of the river south of the Vatican quarter.  Though Julius gave his name to the connecting street, it seems unlikely that Sixtus built the bridge without thought to improved communication with the Vatican, namely the connection that his nephew, Julius, made and called the via Giulia.  The bridge serves as an emblem for his public works in general (as well as his role as pontifex) on the reverse of the medal, by the sculptor who called himself Lysippus, showing the bridge and bearing the inscription CURA RERUM PUBLICARUM.(figs)[32]  The plaque on the bridge states…[Get]  The argument that Julius did not feel a compunction to honour the street joining the Vatican and the Ponte Sisto with the name via Sisto can be extended.  Sixtus, who claimed to be the founder of the Vatican Library through the inscription of the fresco by Melozzo da Forlì, now in the Pinacoteca, and indeed the whole project of Nicholas including the restoration of the acqua virginis, could name the bridge after himself without being the first to conceive it, and could have intended the cutting of the Via Giulia (and via Lungara) too.  Flatterers of Sixtus as a new Augustus in having found the city of brick and left it of marble could similarly be transposing an undertaking that Alberti originally intended for Nicholas.[33]

Alberti, in De re aedificatoria, Book IV, 3, makes the point that a city divided by geographical features more easily descends into factionalism. As sure a sign of ancient Rome’s social collapse as the delapidation of the acqueducts supplying water to a healthy populace was that of its political disintegration – the ruination of the bridges across the Tiber.  The repair of the old bridges promises a true restauracio, the undoing of a division.

Given the nature of the thinking that conceived the Ponte Sisto and the via Giulia and, indeed, the straight street that Julius opened on the Vatican side of the river going southwest to Trastevere, the via della Lungara, it is possible that both Sixtus and Julius were inheritors of an earlier scheme for improved circulation between the Vatican, the abitato and Trastevere.  A Ponte Niccolo and a via Niccolo instead of the Ponte Sisto and the via Giulia would be consistent with other planning actions proposed by Nicholas V.[34]  A straight via Niccolo would have the virtue of the three streets that were to pass from from the Castel Sant’ Angelo to the Platea Sancti Petri.   It would be to imitate the ancient Romans to drive straight streets: they were famous for them.  The via Appia is a famous local example.  As Alberti wrote in De re aedificatoria, ‘…si erit civitas clara et praepotens, vias habere directas amplissimas condecet, quae ad dignitatem maiestatemque urbis faciant.’[35]

Nicholas’ five-point plan could not be realised within the period of a papacy of even a relatively youthful pope.  But one part of his project for Rome and the Vatican did receive especial attention.  The works done in connection with the Ponte Sant’Angelo were in immediate response to the disaster that happened there in Jubilee Year, 1450.  The throng of pilgrims crossing the bridge had been so great that a parapet had given way and many died by drowning.  Nicholas had the Piazza S. Celso opened on the south side of the bridge, presumably so that human traffic across the bridge could be controlled and the transit be made safe.  Two chapels were also created, one dedicated to the Magdalen and the other, the Holy Innocents.  Nicholas was clearly concerned by a problem of transit and circulation here, and the thought emerges that these actions, if limited to the Ponte Sant’Angelo and its immediate surroundings, are more a tactical response than a strategic one.  In other words, another bridge would have done much to ease congestion, especially if it were one-way, allowing pilgrims to return to their lodgings from the Vatican enclave.  In his account of the disaster at the bridge in 1450, Giannozzo Manetti includes the point that it took two-way traffic: ‘tramite hinc ibatur redibaturque.’[36] The Ponte Sant’Angelo was conceived by Nicholas, as it was more explicitly by Bernini when he added the angels carrying the Instruments of the Passion, as an approach to the Vatican, rather than its exit.  The key indicator of Nicholas’ thinking was his building of the keep atop the Castel Sant’Angelo and the placing there of a statue of the Archangel Michael.[37]  The pilgrim is to think of the bridge as the approach to the Throne of Judgement, before which St Michael weighs the souls of the dead.  The sinner had the penitential Magdalen in mind and hope in innocence.  Nowadays, the pilgrim crosses the bridge and passes across the front of the building.  As conceived in the fifteenth century, the pilgrim passed between two towers buttressing the bridge at the north end.  The medal which commemorates the restoration of Alexander VI (1493-1503) shows the arrangement from the south.(fig)  In conventional church architecture, where the Last Judgement is depicted on the west wall, the main door gives the access that the Ponte Sant’Angelo does for the Vatican.  The tympanum above the door of medieval churches frequently carried representations of the drama of the Last Judgement, as happens here.  It is in the context of this progress for pilgrims that the atrium of the church of St Peter’s was the Paradisum.[38] The recognition of Nicholas’s work around the Ponte Sant’Angelo as a species of preaching en promenade makes the bridge emphatically an approach to the Vatican and increases the need for an exit.[39]

The via della Lungara provides such a route, a direct journey to Trastevere and, by the Ponte Sisto, back to the abitato.  This system of circulation (to be operated when the numbers of pilgrims was high) supposes a counter-clockwise direction.  In other words, traffic along the via della Lungara would be in the direction of Trastevere.  People lodging in Trastevere and wanting to go to the shrine of St Peter, would pass across the Ponte Sisto and towards the Ponte Sant’ Angelo.  Controlling traffic where the via della Lungara arrives at Trastevere is the Porta Settimiana, an opening made in the Aurelian Walls.  Alexander VI built the gate in 1498.  However, a gate of some sort has to have been conceived at the same time as the via della Lungara.  Interestingly, the Porta Settimiana is crenellated on the Trastevere side – the better perhaps to dissuade people from using it as an exit, when the Ponte Sisto was to fulfil that function.

If there is no pressing reason to insist that the via della Lungara and the Ponte Sisto were conceived exclusively by Julius and Sixtus, there is reason to suggest that Nicholas’ plan included their provision.  Indeed, the speculation also insists that the plan was more elaborate.  A bridge was to pass, as early as 1450, from the east end of Borgo Santo Spirito to connect with the anticipated via Giulia.  In other words, the aim was the rebuilding of the ancient Pons Vaticanus, Neronianus or Triumphalis whose piers are shown in, for example, the Bufalini Map on 1551 and which is labelled in the Alessandro Strozzi map of 1474.(fig). [40] The plan of Nicholas, Sixtus or Julius did not come to fruition at this point, for the via Giulia, that had begun its way northwards so purposively, ends in a rather sad dead end at the Lungotevere dei Fiorentini, unconnected directly to the Ospedale di Santo Spirito and the rest of the Vatican opposite.

The plan, then, was for a forecourt to the Ponte Sant’Angelo, a piazza on the west side of the Castel Sant’Angelo, three porticoed streets, as described by Giannozzo Manetti, passing up to the Piazza San Pietro,[41] the rebuilding of the Ponte Triumphalis at the end of Borgo Santo Spirito, the cutting of the via Giulia, the building of the Ponte Sisto and the creation of the via della Lungara connecting the Vatican (along via dei Penitenzieri) and Trastevere directly.

Alberti’s particular interest in the Ponte Sant’ Angelo is documented.  He wrote about it in particularly warm terms in De re aedificatoria.[42]  Vasari believed that he possessed a drawing by Alberti of the bridge.[43]

The dilapidated condition of the city presented especial difficulties for the creation of the straight street through the abitato, namely the via Giulia.  That is, it did so, until an accurate map of the city had been made.  This is the practical use to which Alberti’s map is most adapted.[44] Before his map, it was impossible for the magistri viarum to take true command in the pursuit of their task; they could not cut straight streets through the medieval city, because they could not predict with confidence their mathematical-geographical destinations.  But, just as it had been possible to use the distance between any two points on the 1:1 drawing of the dome of Florence Cathedral to check the accuracy of the rising structure, so it was now possible, in Rome, to demolish in a straight line between the Ponte Triumphalis and the Ponte Sisto, when the political and economic obstacles became surmountablee.[45]

There is reason to link the planning of a scheme to connect parts of Rome by straight roads and bridges with Alberti because he had designed the device which allowed straight streets to be created in Rome.  The connection could however be loose; others could have made use of his map.  But it can be argued that his map was invented precisely to solve the problem of how to cut such streets.  If the various data are gathered together, they comprise a body of evidence that he was ambitious to provide a programme and a plan for the city.  Others, also interested in Rome’s restoration and no doubt contributors in the framing of the policy and programme, did not invent the facilitating device.  Historians have noted the circumstantial evidence of Alberti’s contribution to the restoration of Rome and particular works of restoration, like St Peter’s and S. Stefano Rotondo, are direct evidence of his involvement.[46] However, a role much closer to the heart of planning is indicated when Alberti’s debt to Brunelleschi as a mathematical thinker is taken into consideration.  Moreover, his post-mortem presence in the city becomes extended, if Sixtus and Julius became his urbanistic cats-paws.  In light of this thinking, the crucial moment in Rome’s renaissance was indeed around 1450 when Nicholas was pope.  Or else it was around thirty years earlier, when the predictive power of drawing revealed itself; when representation, liberated from necessity – being an a posteriori action – became thought, and able to create the world in its image.

—————–

The 1:1 drawing for the dome of Florence Cathedral seems to have stimulated Alberti to ponder and to develop his mathematical powers of invention as a putative sculptor and infrastructural restorer of Rome.  His most famous invention, however, is to be related prima facie with another of Brunelleschi’s mathematical inventions.  Alberti’s instruction in the first book of De pictura in how the reader might make a pavement in one-point perspective for the later assembly of scenery and cast and the performance of an affecting and morally-improving drama – the historia – is generally agreed to be a codification, for the use of painters, of the practice invented by Brunelleschi and demonstrated in his panel of the Florence Baptistry. 

Antonio Manetti gives a brilliantly lucid account of the panel in the Biography.[47]  It is clear that Brunelleschi demonstrated, crucially, that a picture of the Baptistry was indistinguishable from the real building by an observer located at the geometrical point in space from which all surveying triangulation for the making of the picture had been done, in fact or notionally.  Earlier geometric perspectives had allowed varying amounts and kinds of movement to the observer.  The price paid for that freedom was that the relative sizes of the parts of the object depicted could not be derived from the representation.  Brunelleschi’s demonstration saw the representation containing, in a form encoded by his method of projection, all the sizes that belonged to the object itself. 

A document of 1413 shows that Brunelleschi had already demonstrated his skill as a perspectivalist.[48]  It has been taken by some as evidence that he had developed his one-point perspective system by this time.  However, there was no very special prompting before that date for Brunelleschi to have made the invention.[49] It would be a point demonstrated to no great purpose.  The panel that Manetti describes, however, makes two points emphatically and, if a later date be allowed – after about 1420 for instance – it can be conceived as having emerged out of Brunelleschi’s struggle with a specific problem.  The geometrical point is connected with the remarkable possibility of a true Plinyesque conundrum, the inability to tell the pictured from the real.[50]

The venerable Baptistry could be used to demonstrate the system; however, the use for which the system was designed was not the representation of buildings that had stood for hundreds of years.  There was another building whose real relational sizes called to be represented, in the knowledge that these relations were true to the actual sizes of the structure.  That was the Cathedral dome.  The problem remained one of trajectory, the need to direct the form of the building in the absence of the brute prediction of centering.  There needed to be an invisible building, standing upon the drum, with which the materials of the structure were going to have to coincide.  If Brunelleschi could make that invisible dome visible, he had the means – in theory at least – to regulate the rising building.  The observer of the Baptistry, standing at the required spot in the doorway of the Cathedral, was looking through a hole in Brunelleschi’s panel.  The painted image faced the Baptistry so that, when the observer obstructed the view of the building with a mirror, the reflected painted image coincided perfectly with what was visible an instant before.(fig)  The viewing position in its three coordinates had to be just so, as did the distance of the mirror from the panel.  A painting of the dome to be built, represented from a particular point in space, would, come its completion in 1436, be indistinguishable from the real thing.  In the meantime, life must imitate art, and, in its location, no brick or tile of the building must fail to match the picture.[51]  It is difficult to conceive a better moment than standing in admiration of the dome of Florence Cathedral with, in one’s hand the perspective drawing that predicted it, to observe that this ‘…building is a form of body, which like any other consists of lineaments and matter.’[52]

The 1:1 drawing of the dome had had a shortcoming.  It made checking the accuracy of what had already been done easy.  But, on its own, it did now tell the actual fabric in which direction to grow.  In practice, Brunelleschi probably rigged up lengths of template to guide construction in the immediate future and these would be derived from the drawing –they could also account for irregularities in the fabric.  However, one-point perspective renderings have the virtue that the 1:I drawing lacks; they are distant from the actual structure in a different sense.  By virtue of the measured nature of viewing distance between projection point and panel and projection point and structure, they can be superimposed as visual experiences upon the visual experience of the dome.  Thus, the growing structure and its destination in space coincide as the observer shifts back and forth between experience of the building and of the perspective rendering.

As a device for regulating the growth of the dome, the perspective probably worked better in theory than in practice.  But, in theory, three pictures would have been made, from different points of view at measurable distances from the building.  All would have had holes in them corresponding to the viewpoint or projection point and all would have used mirrors.  Each observer could verify the correctness of an alignment from his point of view.  If all three were in agreement –could wave their green flags as opposed to their red- the element would be in the correct position in space.

A convenient spot from which to observe the building process and to set up the predictive representation of it might have been the top of the campanile.  It is possible to imagine also an activity of observation and calibration like that we conceive, of Alberti, atop the tower of the Palazzo dei Senatori, collecting the data of his Descriptio urbis Romae.

Manetti’s description of Brunelleschi’s Baptistry panel is based on direct experience: he says that he has had it in his hands many times.[53] However, from his account, it does not appear that he took it along to the Cathedral to check its accuracy.  He would not, therefore, have proved the role of the mirror and would be reporting what he was told about it.  It seems unlikely that Alberti, an admirer of Brunelleschi, and of the dome, an inventor of perspective demonstrations and of the costruzione legittima in De pictura was in ignorance of it.  However, his own perspective method – if it did depend upon Brunelleschi’s demonstration panel, was separated from it by a considerable procedural gap.  A free translation rather than a transliteration had taken place.  Indeed, Alberti’s method, if derived from Brunelleschi’s, would have been a radical abstraction.  A speculative reconstruction of Alberti’s thinking, whereby he performed that mutation, would be somewhat attenuated.

In any case, the invention in whose production there are very many fewer problematic steps, the 1:1 drawing, can also be argued to have had a role in enabling Alberti to develop his one-point perspective method.  The Baptistry demonstration, it has been suggested, presented an empirical order of events -there is a Baptistry of which there is a representation- in order to explain a speculative order of events – there is a drawing of which there will be a dome.  The speculative order of events was contained in the relationship of the 1:1 drawing and the material dome that was to be built.  Alberti, in conceiving the costruzione legittima, could fruitfully ponder the 1:1 drawing.

The mechanics of Giovanni di Gherardo da Prato’s action in making the drawing of the quinto acuto, and our sense of the authority of the architectural drawing in general, make it easy for us to think that the requirement at the dome project was for a scaled-up version of the draughtsman’s instruments.  So, there would be needed some sort of rig whereby a fixed point in space could be set, from which the arcs of the structure could be struck.  However, wires and cords do not make straight lines in real space –even more so in a space as vast as that of the Florence Cathedral octagon.  More difficult, but perhaps more fruitful, is to think that a suitable regulatory apparatus would not mimic the action of the architect at the drawing board.

Better perhaps to focus upon another device that was needed – one to establish that a given point in the material structure is where it needed to be.  Brunelleschi’s Castello and Alberti’s Orizonte did that.  Every point in the building and on the surface of the statue, as has been seen, is indicated in terms of two lengths and an orientation.  Students of the Dome project who think of the gualandrino a tre cordi as a means of controlling the arcs of the vault are conceiving a device in terms of orientations.[note ref. gualandrino)

However, Alberti describes another device that specified points  in terms of three lengths.  His costruzione legittima created a pavement.  Any point on it was located in relation to two lengths, orthogonal and transversal.  It was  a two-dimensional ruler.  And, in the practice of the painter, it was a three-dimensional one too, for heights were easy to fix.  The cylinder of the Orizonte is replaced by the reticulated box.  The gualandrino is notable for being a diminutive and for its tre cordi.  Perhaps it was not some great apparatus of wires and cords.  Its three cords perhaps passed off as-it-were on z, y and z axes, again within a notional reticulated box.  It would be set up at any point in the structure of the dome or, on a pole, as the target for the next part of the structure.  And its three coordinates could be set.  Of course, it must be confessed that this apparatus is not without its weakness.  The two cordi in the horizontal plane would still sag.  But they do so in a more controllable way than where tracing paths from the horizontal to the vertical.  They could be referred back to the 1:1 drawing.  Alberti’s costruzione legittima could have evolved out of his understanding of such a role for the gualandrino a tre cordi, as his Orizonte did from the Castello. [this, though it makes sense, is perhaps a bit difficult to follow, and should be amplified]

The predictive –if not directive- function of the 1:1 drawing was its salient characteristic.  In the case of the Baptistry panel, that function was not immediately obvious.  What they share is their mathematical precision and the property of having an existence independent of the real objects that the same mathematics inform.  The 1:1 drawing has no taint of empiricism about it: it has unambiguous priority over the structure.  Alberti’s costruzione legittima lays down conditions for what will at length occupy the picture space.  It does not predict locations of things, but it does insist that all things will be subject to a single rule of diminution with distance from the point of view of the observer (or, at any rate, projection point).  Its priority in the process of creating the historia is absolute.  The brilliance of its conception is that the perspective pavement was, in effect, a two-dimensional ruler, and one easily made into a three-dimensional one.  It thus contained, if the expression may be coined, the totality of virtuality, and can be considered a distillation and universalisation of the 1:1 drawing, the virtual dome of Florence Cathedral.

[connecting Alberti with works around the Platea Sanct Petri and the Benediction Loggia.  Stefano Borso, Leon Battista Alberti e l’antichita romana, p.34-36, reports Poliziano writing that Alberti was instrumental in Paolo Romano being chosen to create the giant statue of St Paul before St Peters.  Mino da Fiesole, Bernardo Rossellino’s associate was also in for the job. (he did something behind the high alter of Santa Maria maggiore, I think)  Check the facts here.  For, though, it’s Poliziano’s remark that is important, he’d have been referring to Pius’s time, though he says that he’s recalling Paul II’s time.  See note 10, p.139 for ref. to Bollettino d’Arte article, 1991.  Borsi conjectures that Alberti had an important role in directing an idea of all’antica sculpture in a normative direction and away from the eccentricity of late Donatello.  See also, p.44, where Borsi notes the use of the word Colossus in connection with the statues of Ss Peter and Paul in a note in Pandino’s Ad divum Pium…  The word, he says, is an Albertian term.]

In connection with the Platea Sancti Petri and the Benediction Loggia, there’s the possibility, that Borsi alludes to (p.46-7) that Alberti’s attemp to to get De statua published was connected with the production of the colossal statues of Peter and Paul.  His apparatus, together with his table of sizes, was ideal for creating statues of different sizes than maquettes and models.

Acqua vergine; Alberti was described as ‘perdoctissimus’ in relation to aqueducts.p.81/127  See also De re Book X, chapter 7

Borsi (125) suggests that Alberti may have been involved in the proposal to build a chapel to comemorate the arrival of the head of St Andrew (May, 1461) at Ponte Molle.  Paolo Romano got the commission (as he had for the statue of St Paul[?]).

Look at Burroughs, JWC, 45, 1982.  It something about Nicholas’s project, involving St Michael.  See also “A planned myth and a myth of planning”.

---

[1] Leon Battista Alberti, Opere Volgari, a cura di C. Grayson Vol III, Bari: Laterza, 1973, Della Pittura: ‘Prese l’architetto, se io non erro pure dal pittore gli architravi, le base, I capitelli, le colonne, frontispici e simile tutte altre cose.”(p.46, lines 9-10): ‘ Nam architectus quidem epistilia, capitula, bases, columnas fastigiaque et hiuis modi caeteras omnes aedificiorum laudes, ni fallor, ab ipso tantum pictore sumpsit.’(p.47, l.11-13)

[2] Grayson, III, Della pittura/De pictura, p.10/11

[3] He showed a similarly cheerful disregard of impractical fastidiousness when, in De pictura/Della pittura, he refused to meditate upon the physiology of the eye and the neurology of vision and insisted in effect that, for the purposes of perspective, the eye be considered a geometrical point.  The eye was the seat of the sense of vision, which otherwise went undefined.  Op.cit., p.16/17

[4] Antonio Manetti, The Life of Brunellschi, p.89, l.944-5

[5] Manetti describes a multitude of aids to construction of the dome.  See, op.cit., p.93, l.998-1026

[6] Preventing an automatic building process, among other factors, was the irregularity of the octagon itself.  The sides vary by as much as half a meter.

[7] Their starting point is a document published by Cesare Guasti, La Cupola di Santa Maria del Fiore, Firenze: Barbera, Bianchi & Comp., 1857.  On 4^th February, 1425, the Opera renewed Brunelleschi’s and Ghiberti’s appointments at the same time as recording a report of 24^th January about the dome. A safety barrier will be erected to that the bricklayers [maestri] will not have to look down, ‘…e morisi con gualandrino con tre corde, faccia dentro e si di fuori.’( Doc 75, p.40).  Ippolito Lamberto and Chiara Paroni (La Cupola di Santa Maria del Fiore, Roma: La Nuova Italia Scientifica, 1997, p.[get]) say that a ‘gualandrino’ was a kind of set square used by stone carvers and metal workers to establish angles.  The term is a diminutive and the apparatus was perhaps not very large.

[8] Archivio Storico di Firenze, Opera di Firenze, 90.  See…[get?]

[9] Orlandi, L’Architettura, III,14: ‘Est tamen inter testudines una omnium recta spherica, quae armamenta non postulet, quando ea quidem non ex arcubus solum constat, verum etiam coronis.[…] Et coronam qui coronae superastruxerit, et in arcum qui alterum arcum perduxerit, fingito velle id opus labescere, unde incipiet? Cunctis praesertim cuneis unicum centrum petentibus pari et viribus et innixu.’(p.245)  That Alberti construed the dome of Florence Cathedral in this way is indicated perhaps by his description of the dome as a corona in the poem that he wrote for the Certame Coronario  the poetry contest that he organised in the Cathedral in 1444.  See, Girolamo (Hieronymo) Mancini, Opera inedita et pauca separatim impressa, Florentiae: Sansoni, 1980, pp.236-37: ‘Dite, o mortali, che sì fulgente corona/poneste in mezo, che pur mirando volete? /Forse l’amicitia, qual col celeste Tonante/tra li celicoli e con maiestate locata,/ma pur sollicita non raro scende l’olimpo/sol se subsidio darci, se comodo possa,/non vien nota mai, non vien composta temendo/ l’invidi contra lei scelerata gente nimica./ In tempo et luogo veggo che grato sarebbe/a chi qui mira manifesto poterla vedere,/s’oggi scendesse qui dentro accolta vedreste/sì la sua effigie et gesti, sì tutta la forma./Dunque voi che qui venerate su’alma corona/leggete i miei monimenti et presto saravvi/l’inclita forma sua molto notissima, donde/cauti amerete.  Così sarete beati’.  The Certame Coronario is discussed at several places, below.

[10] Antonio Manetti (The Life of Brunelleschi) described the process of using ‘…una canna o pertica, ferma dallo lato piu baso, che girassj per tutto, poco a poco ristringiendo, tocchando e mattonj o vero mezane… ‘(l.668-70) Ross King refers to Bartolomeo Scala, in Historia Florentinorum, c.1490, describing a cord stretched to the circumference of the dome.(p.85)  He is clearly talking nonsense.  He may well have mistaken the context of the passage just cited, thinking that it referred to the dome of the Cathedral.

[11] Alberti proposed a modified method for polygonal domes: ‘Angularem quoque testudinem  sphericam, modo pro eius istius crassitudinem rectam spericam interstruas, poteris attollere nullis armamentis.’ Grayson, III, 14, p.247.  Mainstone argues that the wall-head of the octagon was wide enough to enclose a circular ring [ref].   This is questionable for two reasons. All the structural matter of the dome, at springing level, would have to have fallen within the circle.  This does not seem to be possible. The second point is that the dome, viewed from within the building, retains its octagonal form at that level.  Moreover, if the circle had been achievable, the faceted  form of the dome was unnecessary.  The counter-argument –that the facetted nature of the drum needed to be continued into the dome itself- is unconvincing where the virtue of the dome rising out of a circle is so obvious.

[12] See Eugenio Battisti, Brunelleschi: The Complete Works, London: Thames & Hudson, 1981, p.124.

[13] It is easy to conceive a device based on Giovanni di Gherardo’s drawing (ASF. Opera di Firenze, 90).  Let wires be stretched from the angles of the octagon through the centre at the level of the springing.  At one fifth of the length of these wires others are attached, four fifths of the length.  These points are connected by a ring of wires of equal length, creating an octagon in the plane of the springing of the dome.  It is now possible, in theory, to regulate the profile of the dome at the eight angles.  In order to regulate the eight surfaces of the dome rising from the sides of the octagon, another octagon has to be fixed in the springing plane with a greater diameter than the first (because the dome, on the shorter diagonal has to reach the same height as that on the long).  Wires long enough to reach the far faces of the octagon would be attached to this larger octagon by loops, so that they can be shifted along the wire, or line, that is parallel to the panel of the dome that curves upward between the angles of the octagon.

[14] A more obvious use for a 1:1 drawing is for the making of templates.  The Gothic mason frequently had 1:1 drawings of parts of the building under construction to which he could address, presumably, the stone that he had cut.  At Florence, however, a 1:1 drawing to be used in this way would only have to have been one eighth of the dome, since templates for any part of the dome can be got from a drawing of one segment of it.  The drawing that Brunelleschi made was to regulate growth, establishing distances and orientations.

[15] Alberti, De re aedificatoria, IX,5

[16] Leon Battista Alberti. De statua, a cura di Marco Collareta, Livorno: Sillabe, 1999

[17] He praised the dome and Brunelleschi’s genius in the prologue to Della pittura.

[18] The closeness of the thinking of De Statua to Alberti’s experience of Brunelleschi’s dome could carry the implication that the treatise was written close to events, and therefore close to 1435/6 when he produced De pictura/Della pittura

[19] See, Albertiana, Vol.VI, 2003, Leo S. Olschki Editore, pp.125-215 (various authors). 

[20] The data indicating the whereabouts of the monuments of Rome would have been like those indications of dimensio and finitio in De statua in that the one would allow the map to be drawn anywhere and the other would allow the statue to be made at any time in the absence of the original model.  See De statua, para 4, p.6. [a quote perhaps] In para 5, Alberti goes on to observe that, with the data of dimensio and finitio, it would be possible to make one half of a statue in one place and one in another, and the parts would fit.

[21] The elements of the procedure are deployed for map-making and distance-finding in Ludi Mathematici, Alberti, Opere Volgari, Vol.III, Bari: Laterza, 1973, pp.163-69.

[22] Mario Carpo, “Alberti’s Vision and a Plan for Rome”, Albertiana, VI, 2003, pp.209-214

[23] Poggio Bracciolini, “De varietate Fortunae”, in Opere Volgari…[Get]

[24] Orlandi,L’Architettura, X,7, p.923; Rykwert et al, p.337: ‘This circle is called a horizon.’

[25] Torgil Magnuson discusses Manetti’s account in Studies in Roman Quattrocento Architecture, Stockholm: Almquist & Wiksell, 1958, pp.55ff.

[26] Orlandi, L’Architettura, Prologue, p.13; Rykwert et al, p.5: ‘As to the imperial authority and fame that the Latins got by their building, I need only mention the various tombs and other ruins of past glory visible all around, which have taught us to accept much of the historical tradition that may otherwise have seemed less convincing.’

[27] Alberti, De re aedificatoria, X,17.  If Alberti hoped to gain the pope’s confidence in him as a director of urban renewal by presenting him with a copy of De re aedificatoria, the presence in the text of passages that the pope could contrue as criticism of his own actions is surprising.  It is possible that the following passage was added later but, if not, if is difficult to think that Nicholas would not have thought that the battered and crenellated Nicholas Wing of the Vatican Palace was an intended target of criticism: ‘I do not share the affectation of some of endowing private habitations with battlements and pinnacles; a habit which suits as best fortresses, and in a particular way tyrants, and for that reason is far from suitable for a well-ordered state and a peaceful citizenry, because it implies an attitude of fear and being crushed.’ Alberti, IX,4, p.809

[28] [get check Burroughs says the dedicatee of Roma Instaurata was Nicholas V

[29] Ref. Magnuson, Westfall etc

[30] He concludes his description of the procedure: ‘Nos circuli istius adminiculo ad urbium provinciarumque descriptione, annotandam atque pingendam, ad cuniculos etian subterraneos producendos bellissime utimur.’ Orlandi, L’architettura, X, 7, p.925:  Rykwert et al, p.338: ‘This circle is very useful for marking and drawing maps of a city or province, and also for plotting underground conduits.’

[31] Certainly, the drift of Giannozzo’s report of Nicholas V’s deathbed speech to the cardinals, is that the project begun is to be continued.  At the beginning, Nicholas orders them to listen to the reasoning driving the scheme (‘Audite, audite … rationes…’) and to give consideration to its ongoing aims (‘…causasque considerate’).  See, Smith and O’Connor, p.472.  He asks the cardinals to continue and finish the works: ‘…venerationes vestras … exhortamur, quatenus predicta constructionum nostrarum opera incoata prosequi ac perficere et absolvere velitis…’ (.p.482)

[32] For a discussion of the bridge as one of Sixtus IV’s principal public works, see Jill E. Blondin, “Power made Visible: Pope Sixtus IV as Urbis restaurator in Quattrocento Rome”, The Catholic Historical Review, Vol.XCI, January 2005, No.1, pdf. p.1-25

[33] Egmont Lee, Sixtus IV and Men of Letters, Roma: Edizioni di Storia e letterature, 1978, pp.123-24, quotes Giovanni Campano and Raffaello Maffei to this effect.

[34] A sense of pious debt to the father of an innovation could have been lacking here, as it was when Sixtus IV announced himself the founder of the Vatican Library, in the painting by Melozzo da Forli now in the Pinacoteca, usurping Nicholas’s claim.

[35] Orlandi, L’Architettura, IV,5, p.305-7; Rykwert et al, p.106: ‘When the road reaches a city, and that city is renowned and powerful, the streets are better straight, to add to its dignity and majesty.’

[36] Christine Smith & Joseph O’Connor, Building the Kingdom: Giannozzo Manetti on the material and spritual edifice, Arizona Centre for Medieval and Renaissance Studies,, Tempe, Arizona, in collaboration with BREPOLS, 2006, p.372

[37] The present statue by Antoon Verschaffelt [1752] is the last of several replacements.  St Michael’s presence also alludes to a vision of Gregory the Great in 590 and a recurrence during the plague of 1348.  Gregory saw an angel atop the mausoleum of Hadrian sheathing a bloody sword and took it as a sign that the plague had been lifted from the city.  (Golden Legend Get.)  Nicholas replaced a figure of St Michael that had been destroyed in 1379.  See Carroll Westfall, In this Most Perfect Paradise, University Park and London:  the Pennsylvannia State University Press, 1974, p.100; Charles Burroughs, From Signs to Design, MIT Press, Cambridge Massacusetts, London, 1990, p.73.

[38] This dramatisation of the pilgrims’ way was made very much clearer and more elaborate by Bernini in the seventeenth century. In the middle of the  fifteenth century, a very considerable addition to the St Peter’s complex was the Benediction Loggia in front of the atrium and atop a broad flight of steps.  The work was begun in the time of Pius II.  However, it too can be thought of as participating in the drama that first begins to unfold with the crossing of the river under the gaze of the Archangel Michael and was conceived, in general at least during the papacy of Nicholas.  Giannozzo Manetti tells of how, at the east end of the palace, “Super hoc atrium coenaculum magnum anniversariis et ordinariis summi pontificis benedictionibus designatum aptabatur, quod versus Orientem in pontem molis Adrianae respiciebat.” (Torgil Magnuson, Studies in Roman Quattrocento Architecture, Stockholm: Almquist & Wiksell, 1958, p.355).  At the end of his account of Nicholas V’s works of building in Roma and the Vatican, he compares St Peter’s with the Temple of Solomon, whose magnificence the former exceeds.  Among other things, where the Temple has one portico, St Peter’s has three.(p.362)  He would be counting the confronting porticos of the Atrium and one other.  If this third refers to the Benediction Loggia, which was not yet built in Nicholas’s time, Giannozzo would appear to be consulting a drawing or model rather than a built fabric.  There is a note of boyish glee in his description of the Vatican works that suggests that he might have been pouring over a drawing or model as he wrote.  He uses the imperfect tense and sometimes describes things that had not been done.  For example, he goes on immediately to say that the obelisk that stood actually to the south of the church of St Peter’s (it was in fact the goal of the southernmost of the three streets passing west from the Piazza by the Castel Sant’Angelo) was placed [collocabat[ur)]  in the Platea Sancti Petri.  The people were to be gathered together for the experience of spectacle.  Had the Benediction Loggia been built beyond the four bays actually erected, to the number that would extend the whole width of the steps built by Pius II, the clergy and choirs gathered in it on the three levels would have put the faithful in mind of the heavenly host. 

[39] A fine sense of the pressure put upon the Ponte Sant’Angelo as the single link with Rome to the south is given in the Cronache Romane quoted by Pastor: ‘In Holy Week the throngs coming from St Peter’s, or going there, were so enormous that they were crossing the Bridge over the Tiber until the second and the third hour of the Night.’(Ludvig Pastor, The History of the Popes, London: Kegan Paul, Trench, Trubner & Co,, Lid., 1923 (fifth edition), Vol.II, p.84)

[40] Braun and Hogenberg’s map in Civitates Orbis Terrarum, Vol.II, of 1575, shows the bridge ‘rebuilt’. [check Giovanni Rucellai’s description of the jubilee pilgrimage route. 68] [ check Magnuson.  Did Manetti say that Nicholas planned the restoration of acqueducts and bridges?] [A question to address is whether the line of the old bridge was to be followed, in which case it would line up with the via Recta, or only one of its piers would be used as part of a bridge continuing the line of the via Giulia.  See Tafuri on this point.]

[41] In De re aedificatoria (Orlandi, L’Architettura, VIII, 6, p.709), Alberti describes one of ancient Rome’s two sacred streets: ‘…the latter is 2,500 feet in length and protected by a portico of marble columns and lead roofing,’ Rykwert et al, p.261

[42] Orlandi, L’Architettura, VII,6.  It was, at one time, roofed:’…aliquibus etiam tectum: quale Romae ad pontem omnium praestantissimum Adriani, opus, me superi!, dignum memoratu, cuius etiam, ut ita loquar, cadavera spectabam cum admiratione.  Steterat enim illic tectum columnis excitatum quadraginta duabus marmoreis, opera trabeato, tectura aenea, ornatu mirifico.’(p.711) Rykwert et al.  ‘Some bridges even have a roof, like that of Hadrian in Rome, the most splendid of bridges – a memorable work, by heaven: even the sight of what might be called its carcass would fill me with admiration.  The beams of its roof were supported by forty-two marble columns: it was covered in bronze and marvelously decorated.’ (p.262)

[43] Vasari, [get ref. Alberti drawing of ponte Sant’Angelo ref.  See also, below]

[44] Alberti’s general enthusiasm for practical inventions that emerges clearly from Ludi Mathematici and is noted in Profugiorum ab aerumna [get], produces a very agreeable object in the form of the map of Rome and the table of coordinates.

[45] After describing the Ponte Sant’Angelo, Alberti goes on to the describe the bridge that he would build. This ideal bridge (ibid.) does not differ in important particulars from the Ponte Sisto though it does lack some refinements.  Orlandi, L’Architettura, p.711ff.; Rykwert et al, p.262ff.

[46] Borsi, 1986, p.41-50

[47] Antonio Manetti, The Life of Brunellschi by Antonio di Tuccio Manetti, Introd, notes and Critical Text Edition by Howard Saalman, English Translation by Catherine Enggass, Pennsylvania State University Press, University Part and London, 1970, p.43-5, l.167-203

[48] In a letter of 1413, Domenico da Prato, writing to Alessandro di Michele Rondinelli, referred to ‘…prespettivo, ingegnoso uomo Filippo di ser Brunellescho, ragguardevole di virtudi e di fame.’ See, Hugh Hudson, ‘The Monuments of Florence, Real and Imagined in the Earl Renaissance: The Development of the Single-point Perspective in Painting’, in Place, an interdiciplinary e-journal, p.1

[49] Eugenio Battisti (Brunelleschi: the complete works, Thames & Hudson: London. 1981, p.102) notes that Brunellschi was Prior of the S. Giovanni Quarter in 1425 and the banners of the district bore an image of the Baptistry. (p.102) The genial thought follows of Brunelleschi’s tenure seeing new banners for old.

[50] Ghiberti’s suggestion in his Commentaries that Pliny’s story of Apelles’ fine line might better have been a demonstration of perspective fits with this aspect of the demonstration of Brunelleschi.  Brunellschi’s Baptistry was as real to its observer as was the bunch of grapes painted by Zeuxia to the bird that pecked them.

[51] Or the picture could have been of an element now obscured by the tiles: ‘E tra la pelle delle chupole … sono im varj luoghj varj provedimenti e sue industrie.’ Antonio Manetti, The Life of Brunelleschi, p. 92 and p.93, l.1000-03)

[52] Rykwert et al, p.5; Orlandi, L’architettura,  Prologue, p.15: ‘Nam aedificium quidem corpus quoddam esse animadvertimus, quod lineamentis veluti alia corpora constaret et materia…’

[53] Antonio Manetti, The Life of Brunelleschi, : ‘E io lo avuto in mano e veduto piu uolte a mia dj e possone rendere testimonianza.’ (p.44/45, l.202-03)

.[He also gives an account of proposals for the Platea Sancti Petri: ‘Ante primum igitur hujus sacrae aedis vestibulum super scalas prominens maxima quaedam area quingentorum in longitudine, centum in latitudine cubitorum pulcherrime apparebat.  A formosis namque praedicti vestibuli gradibus, quos partim marmoreos partim porphyreis, partim smaragdinorum colorum decoris, gratia interferebat, incipiens, usque ad egregia et nobilitata intercolumnia per quingentos, ut diximus, passus in longum extendebatur, super quibus tres commemorati vici porticus, speciosorum omnium spectaculorum visu pulcherrimum specimen, sustentabantur.’ (Magnuson, p.356).