The exploitation of these marbles was rendered difficult at Pisa by the marshy nature of the ground at the foot of the hills which impeded transport, and Duke Cosimo set himself to find a remedy. He took up the question of drainage and regulation of watercourses in what is called the ‘pianura di Pisa,’ and among the forty medals struck to celebrate his various achievements were some for ‘Clima Pisano Risanato.’ In 1545 an ‘Uffizio dei fossi’ was constituted, and the modern hydraulic system which has done so much to benefit this region, dates from these measures of Cosimo. Vasari, § 11, ante, p. [50], speaks of a river ‘Osoli’ the course of which was straightened and confined. This is probably a mistake for ‘Oseri’ or ‘Osari,’ names applying to one of the small streams close to Pisa in the direction of the quarries. Targioni Tozzetti in his Viaggi in Toscana has a long discussion on this river, the Auser of the ancients, for which he gives the modern equivalents ‘Oseri,’ or ‘Osoli’ (the latter probably derived from this passage in Vasari). There is a ‘Fossa dell’ Oseretto’ to the west of the city. These straightened watercourses facilitated the transport of the stone in barges.
Continuing southwards along the coast we come to some marble quarries mentioned by Vasari on the promontory of Piombino, opposite the island of Elba. The locality Vasari names is Campiglia (§ 10, ante, p. [50]) but the whole of Monte Calvi above that town is marble-bearing, and the products were said to be as good in quality as those of the Carrara district (Torelli, l.c., p. xc). Vasari says that the Campiglia marbles are excellent for building purposes, and Repetti asserts that in the fifteenth century, for the cupola of S. Maria del Fiore, more marble was used from this region than from Carrara itself. The ancient reputation of the district is not however now maintained.
Hitherto all the marbles used for building purposes that Vasari has mentioned have been white or variegated, but everyone who has visited the Tuscan cities knows that the decorative effect of the buildings depends on the juxtaposition of bands of white and of black, or at any rate, dark marble, with occasional bands of red. The dark marbles come chiefly from the neighbourhood of Prato, and this introduces us to a group of inland quarries within a few miles of Florence to the north and also to the south and east. Vasari does not say much about this dark stone, which was however of the utmost importance in Tuscan architecture. It is commonly called Prato Serpentine, or ‘Verde di Prato,’ and the quarries at Monte Ferrato, by Figline, three miles north of Prato, produce it of the finest quality. The Figline quarries are reported on by Professor Bonney in a paper on ‘Ligurian and Tuscan Serpentines’ in the Geological Magazine for 1879. He has kindly lent us the specimen from the quarry figured as E on the Frontispiece. This stone is of a deep green colour, tending sometimes towards a purple or puce tint. Stone of much the same character is found, as Vasari states, near the Impruneta, six or seven miles east of Florence. It is this Prato Serpentine that has been so largely used from the twelfth century to the fifteenth in Tuscany for alternating with the white marbles in the incrustation of façades. There are deposits of the same stone in the Pisan mountains. The same stone was sometimes used for decorative stone work in connection with sepulchral monuments. According to Vasari however, ante, p. [42] f., it was the ‘paragone’ or dark limestone of Prato that was chiefly employed for this purpose.
If Vasari’s information about this important stone, and his interest in it, seem scanty, it must be borne in mind that it was a mediaeval material rather than a Renaissance one. We find it on the churches and bell towers and baptistries of the twelfth and following centuries, but not on the palaces of the fifteenth and sixteenth. Hence the stone was not so interesting in Vasari’s eyes as it is in ours.
Finally, the red stone seen in bands on the Duomo and the Campanile at Florence, that Vasari calls ‘marmo rosso’ (ante, p. [43]), is not fully crystalline and is rather a limestone than a marble. It is deep red when quarried, but on the buildings has bleached to a pinky hue from exposure to the air. It is apt to scale, but this is partly due to its not being laid on its proper bed. The specimens F F on the coloured plate show the smoothed external surface bleached light by exposure. We are informed by Signor Cellerini, the experienced capomaestro of the Opera del Duomo at Florence, that in old time this stone was quarried at Monsummano, at the northern extremity of the Monte Albano not far from Pistoja. A more modern source of supply is the Tuscan Maremma, where the stone, called ‘Porta Santa,’ is quarried between Pisa and Grosseto, near Gavorrano. From this place the stone has been brought for recent use on the new façade of the Duomo at Florence.
Other Tuscan marbles, such as those of Siena, that are not referred to by Vasari, are not noticed in this place.
THE ROUND TEMPLE ON THE PIAZZA S. LUIGI DEI FRANCESI, AND ‘MAESTRO GIAN.’
[See § 12, Of Travertine, ante, p. [51] f.]
It is surprising that practically nothing appears to be known, either about the French sculptor mentioned here, ‘Maestro Gian’ (or Jean), or about the French wood carver of the same name called by Vasari ‘Maestro Janni,’ who is referred to at the close of the ‘Introduction’ to Sculpture, postea, p. 174. Equally strange is it that their works, which Vasari describes in terms of high praise, and which are in public view in Rome and in Florence, do not seem to have attracted attention among students either of French art or of Italian. The standard older book on French artists abroad, Dussieux, Les Artistes Français à l’Étranger, Paris, 1856, takes no note of either of them, nor are they referred to in Bérard’s Dictionnaire Biographique des Artistes Français du XII au XVII Siècle, Paris, 1872. In the more recent Italian work however by A. Bertolotti, Artisti Francesi in Roma nei Secoli XV, XVI, e XVII, Mantova, 1886, there is a mention on p. 220 of ‘un Giovanni Chavenier, che forse disegno quel tempio tondo, attribuito dal Vasari all’ architetto Jean,’ and on p. 24 it is said that ‘Giovanni Chiavier, o Chavenier, di Rouen lavorò pel Governo pontificio e morì a Roma nel 1527.’ Bertolotti unfortunately gives no references to his authorities, while the work of Müntz, Les Arts à la Cour des Papes breaks off before the sixteenth century, and gives no help.