Friday, June 16, 2017

True Colors

The European Roller [Pica Marina]
Antonio Neri's book, L'Arte Vetraria, is devoted to making glass from raw ingredients found in nature. Many of his finished creations were intended to also resemble the natural world. A number of colors are meant to mimic the appearance of gems and minerals, others are named after plants and animals. Some are easily recognized today, even if they are not as familiar as they were in the seventeenth century. One of his recipes will make "a wonderful pimpernel green," while others evoke peach and orange blossoms. An entire section of the book is focused on paints that are named after the flowers from which the colors are extracted. Many of these plants have remained common: poppies, irises, violets, lilies, carnations and red roses. Others are less so: the mallow, pomegranate, broom and borage flowers.

In addition to flora, the fauna make a few notable appearances in Neri's book. In chapter 16, in the preparation of iron oxide pigments, he advises that after fifteen days in the furnace, the product will be finished when it takes on the purple color of the peacock. In chapter 73 he gives a method for "tinting rock crystal the color of a viper" and chapter 121 is the method for a glass which is "red like blood."

Named in several chapters is a shade of 'celestial blue,' which Neri likens to the color of the "gazzera marina." Common bird names pose a special challenge for translation in that they, like the birds themselves, never seem to settle in space or time for very long. Vernacular names of a species can change from one century to the next, one region to another, even between adjacent valleys and several species can share the same name. It is with this admonition that we attempt to flush out the elusive gazzera marina.

Consulting a modern Italian dictionary draws the eye to the similar sounding 'gazza marina' (alca torda), known in English as the razorbill. This sea bird inhabits coastal cliffs, but alas, as a close relative of the penguin, it dons only black and white formal attire. Digging deeper we find poet Gabriele d'Annunzio, "At Dawn" carefully tracking the gazzera marina across a salty marsh, in his Halcyon. This time the poet himself throws us off the trail with his description, since no bird sports five digits but the chicken. Turning to etymology, we find another potential match in the magpie (pica pica); it is a credible but unconvincing fit with its blue and white plumage.
Aldrovandi's pica marina
Combing the references of Neri's own sixteenth century, we find the best candidate is the roller (pica marina). This bird was described by naturalist Ulisse Aldrovandi, a friend of Don Antonio de' Medici's father and guest at the Casino di San Marco, where Neri later worked. Other contemporary authors list the gazzera marina as a synonym to Aldrovandi's pica marina. Neri's Latin translator Frisius (1668) and his German translator Geissler (1678) agreed, both sighting the "Pica Marina" in their works.

This post first appeared here on 13 Sept 2013.

Wednesday, June 14, 2017

The Cardinal's Ceiling

From "Tesoro del Mondo" (Treasure of the World)
Antonio Neri 1598-1600
In the years 1598-1600, newly ordained Florentine priest and alchemist Antonio Neri was hard at work on a manuscript which he titled Tesoro del Mondo (Treasure of the World). [1]  One illustration near the front shows an allegorical map in which six roads all lead to the Vatican at its center. A Latin inscription translates as, "The different ways to Rome" followed by "Qui pot[est] capere capiator 'He that can take, let him take it.' Taken in context, this Biblical reference ( Matthew 19:12) apparently refers to the various alchemical 'paths' leading to the philosopher's stone, but the choice of imagery suggests that Neri spent time in the city of seven hills. [2] It is a tantalizing clue to his travels, although there is no direct confirmation. 

If Rome did figure in the young Neri's itinerary, a visit to Cardinal Francisco Maria Del Monte would have been de rigueur. The Medici family ruled Neri's home region of Tuscany and Cardinal Del Monte was the Medici's informal ambassador in Rome. He was a dedicated patron of the arts, an amateur alchemist, a collector of glass and a trusted successor to Grand Duke Ferdinando in the College of Cardinals. More significantly, he was a close friend and advisor to Neri's sponsor Don Antonio de' Medici ever since that prince was a child.  Del Monte's biographer Zygmunt Waźbiński offers, "It is very likely that Cardinal Del Monte, with his interest in glass, had known then (in 1598) the [future] author [Neri] of L'Arte Vetraria." [3]
Michelangelo Caravaggio, c. 1597
Casino Ludovisi.

As the sixteenth century ended and a new one dawned, Del Monte sheltered the rough-and-tumble painter Michelangelo Caravaggio, whom he set up with an in-house studio and an allowance. However, in 1606, the master of Realism fled Rome after reportedly murdering a tavern waiter over a tennis wager, but not before executing his only known fresco on the vaulted ceiling of Del Monte's own alchemy laboratory. Looking out over Rome, on the panoramic Pincio, in the Villa that later became the Casino Ludovisi and is now known as the Casino dell'Aurora, Caravaggio put his brush to work. According to early biographer of artists, Gian Pietro Bellori, he executed the oil painting on the vaulted ceiling of the small alchemical laboratory (now a corridor) sometime between 1597 and 1600. [4] Depicted in the mural are the three brothers Jupiter, Neptune and Pluto: the masters of the universe. The image is a double allegory of the three basic chemical substances of Paracelsus (salt, sulfur and mercury) and the four Aristotelian elements (air, earth, water and fire). Jupiter with the eagle stands for sulfur and air, Neptune with the seahorse stands for mercury and water and Pluto with the three-headed dog Cerberus stands for salt and earth. Jupiter is reaching out to move the central celestial sphere in which the sun (fire) revolves around the earth. [5] 

The villa was a relatively secluded retreat where the Cardinal could entertain guests discretely, including his friend Galileo–Del Monte and his older brother Guidobaldo helped land Galileo the chair of mathematics at the university in Pisa. It would be interesting to hear the astronomer’s comments on Caravaggio's tribute to heliocentrism.


[1] Neri 1598-1600, f.xxviii-v.  (see bibliography).
[2] For more on the alchemical interpretation of this illustration see Grazzini 2012.
[3] Neri 1612.
[4] Bellori 1672, pp. 197-216.
[5] Wallach 1975, pp. 101-112.

* this post first appeared in a slightly different form on 4 July 2014.

Monday, June 12, 2017

Neri & the Portland Vase

The Portland Vase
(British Museum)
287 years ago this month, (12 July 1730) marks the birth of Charles Darwin's grandfather, English potter Josiah Wedgewood. He founded the company that still bears his name, a name that has become synonymous with the iconic blue with white bas-relief cameo-themed jasperware pottery.  

What is less well known is that the style was developed over several years by Wedgewood in an attempt to copy a particular ancient glass object, now called the Portland Vase. This piece was and still is regarded by many as the pinnacle of ancient glass art. The vase was made around the time of the birth of Christ and shortly after the invention of glassblowing. The prevailing theory states a dark, cobalt blue vase was blown and then coated in a second thin layer of white glass. The piece was then carefully sculpted, probably by a gem carver, by grinding the white over-coat glass into various mythological scenes. The figures stand on dark blue ground that was revealed by completely grinding away areas of white, leaving only the under-layer. 
Wedgwood's Sydney Cove Medallion

Alternate thinking has the piece cast or blown into a mold which contains powdered white glass in the appropriate areas. [1] 
Both theories have their points, and the wide differences only serve to emphasize how little we actually know about ancient methods and technology. Having said that, the alternate theory, it seems to me, has an up-hill battle to gain acceptance over the prevailing one.

What is especially revered by aficionados, and gave Wedgewood the most trouble in replicating, is the delicate carving of the white glass. The figures depicted around the vase in various scenes are not monochromatic, but expertly shadowed just like a fine painting. This, it is commonly thought, was achieved by grinding the white glass so thin that the dark blue under-layer starts to show through, making gradations of lighter and darker features. A face or a hand was shaded by making the white glass slightly thinner on shadowed areas. Wedgewood's solution was to subtlety tint the white clay he used, which was then applied to a blue clay vessel and fired in a kiln. One of his early successes, owned by Darwin, can be viewed at the Victoria and Albert Museum in London.

Today the original Portland Vase can be viewed at the British Museum where it has taken a place of pride almost since the museum’s inception. A series of unfortunate accidents and one act of intentional destruction have broken the vase several times, but it has been painstakingly pieced back together and restored so that cracks are minimized. One of these events occurred during the Roman Empire, when the bottom of the vase was replace by a circular medallion of the same style cameo glass. In modern times, the vase was the subject of a nineteenth century contest, with a prize of 1000 pounds, to make an accurate reproduction in glass. The winners of that contest were glass blower Philip Pargeter and engraver John Northwood. Their piece is on display in the Corning Museum of Glass in New York.

The vase was uncovered in the late sixteenth century during an excavation, when the hunt for ancient tombs around Rome was in full swing. It was presumably used as a funerary urn in what, at the time was thought be the tomb of Emperor Alexander Severus. It's first owner after discovery was none other than Cardinal Francesco Maria del Monte, patron of the arts, alchemist, glass collector and Medici family confidant, of whom I have written here before. The cardinal was a lifelong advisor to Don Antonio de' Medici, who was in turn, the patron of glassmaker Antonio Neri. There is every chance that Neri and Del Monte knew each other, although no such record has yet been found. Del Monte is known to have visited the Casino di San Marco in Florence at the time that Neri was making glass there and Neri is conjectured to have visited Rome a couple of years earlier. 

If Neri the priest was ever granted audience with the cardinal in Rome at his main residence, the Palazzo Madama (now occupied by the Italian Senate), it is easy to imagine a tour of the cardinal’s extensive glass collection, which he displayed in a special room dedicated to the purpose. Such a tour would not be complete without an examination of what would become the most famous piece of glass in history, the Portland Vase, by the man who would become the most famous glassmaker in history, Antonio Neri. "Go ahead, take it – hold it up to the light."

[1] For more on this see http://rosemarie-lierke.de/English/Cameo_glass/cameo_glass.html

Friday, June 9, 2017

Galleria dei Lavori

Giovanni Stradano  (Jan van der Straet) 
Alchemy Studio, 1571
(Inside the Uffizi Galleria dei Lavori)

In 1560, Cosimo I, Duke of Tuscany, commissioned Georgio Vassari to begin construction on the Uffizi Palace in Florence. Two wings of the structure frame a long, narrow courtyard leading out to banks of the Arno River. Today it houses one of Europe's premier art museums, but its original design was as the central administration of the Medici government. The lower floor held offices of the regional magistrates, and the upper floor of the west wing (above the mint) held a variety of workshops highlighting Tuscan industry. Grand Duke Cosimo de' Medici built a glass furnace there, which he staffed with Muranese masters of the art. He won their expertise through long, hard negotiations with the doge of Venice. 

A 1571 painting by Giovanni Stradano is entitled the Alchemy Studio. It shows Cosmo's son, Francesco I, in the Uffizi surrounded by laboratory equipment and workers. Under the watchful eyes of a senior alchemist, he stirs a chemical preparation over a stove with intense concentration. The prolific glassware in this scene drives home the close relationship between glassmaking and scientific investigation.

By 1588 Francesco's brother, Ferdinando I de' Medici, formally declared this space the Galleria dei Lavori or 'gallery of the works'. There is no direct evidence that Antonio Neri gained his education in alchemy at this facility, but it makes a very attractive candidate. Of note to this story is that a demonstration was performed for Ferdinando de' Medici in Rome that purported to turn half of an iron nail into gold; the work of German alchemist Leonhard Thurneysser. In the 1590s, when Neri was being schooled, several accounts describe that the nail (chiodo) remained on display for some time in the Galleria. Neri mentions the nail in his Discorso and Thurneysser is discussed in a 1601 letter to the priest from his friend Emanuel Ximenes.

After Neri's death in 1614, his Medici sponsor, don Antonio commenced a search for the glassmaker's secret of transmutation, which Neri had promised. In testimony given by a royal goldsmith, who had, in July of 1596, witnessed a demonstration in which "gold" was made by Neri, he pressed the glassmaker, who told him that the transmutation was a technique learned from a German, done with ordinary vitriol.  

It is interesting to note that when iron is soaked in a solution of "blue vitriol" now known as copper sulfate, an ion exchange reaction takes place, where the liquid deposits copper and takes up iron from the nail. It would be well into the 18th century before this chemistry was adequately understood. What the royal goldsmith would have seen is  a dull iron nail turn the color of yellow metal before their eyes. Perhaps the goldsmith was not given the opportunity to further test the sample. 

This post first appeared on 16 August 2013.

Wednesday, June 7, 2017

Weights and Measures

Ford Madox Brown,  The Manchester Murals: 
"The Proclamation Regarding Weights and Measures, 1556."
In his book L'Arte Vetraria, Antonio Neri's glass recipes depended on precise amounts specified in units as small as the 'grano,' [grain] named after the weight (mass) of a single grain of wheat or barley. In interpreting his formulas, the glassmaker must understand the quantities he used. For us, there are unfamiliar units like the 'fiasco' and the 'dita.' The dita or digit was simply the width of a finger. A fiasco or flask was the volume of a glass wine bottle, about two-and-a-quarter liters in Florence or two-thirds of a US gallon - about half of British imperial gallon. (As an aside, there are many fanciful stories of how the word 'fiasco' came to be synonymous with failure or disaster, perhaps the most believable is that the losers of competitions or bets were expected to buy the next round of drinks.)

In addition to unfamiliar units, there is the problem of standardization; a pound in Florence weighed different from a pound in other areas as close as Massa or Piedmont. Each Italian city maintained its own set of master weights and volumes to which merchants were expected to adhere. In reality, the differences were minor and may have been more attributable to politics than accuracy. Since antiquity, commodity merchants realized that if their own set of weights used in sales were ever so slightly below the norm, over time a savings would be realized, not large but significant. Towns could apply this principle as well; it paid to set standards slightly above or below neighboring towns from which one was buying or selling various goods. In truth, the differences were not great simply because successful commerce demanded that buyers and sellers could agree and strike a deal.

Even in different countries throughout Europe and the Mediterranean, we find close agreement in the various units of measure. Neri's first translator, Christopher Merrett, made an interesting substitution in his 1662 English version of L'Arte Vetraria. In chapter 132, Merrett writes "six pints of water" for Neri's "libre sei di acqua," changing pounds into pints. At first, it seems odd to be converting weight into volume, but this was perfectly valid. At that time in England, the pint was defined as exactly a pound (of wine or beer). Sailors were often each allotted a pint a day; the pint was also one-eighth of a cubic foot. (A cubic foot was equivalent to a gallon.) This system was very convenient for shipping companies who needed to calculate cargo volume and ballast in their trade ships as well as avoid mutiny caused by running out of beer at sea. Later, in 1824 King George IV increased the gallon from eight to ten pounds of water, invalidating Merrett's substitution.

Other conversions were more problematic. As absolute measurements varied from place to place, the size of a batch would be larger or smaller; not a big worry. However, ratios were of critical importance to a recipe. Just as in baking a cake, an entire batch of glass could be ruined by changing the ratio of materials. This sort of difficulty was especially prevalent with the size of an ounce; the troy and apothecaries system were based on a twelve-ounce pound while the avoirdupois system used a sixteen-ounce pound. When Merrett wrote his translation, England had officially been under the avoirdupois system since Henry VIII (although, In 1588, Elizabeth I complicated matters further by raising the weight of a pound by about twenty-one percent.) Meanwhile, Florence and much of Europe continued to use the troy system.

English glassmakers who wished to use Neri's book as a working document would need to know which system to use. Merrett's direct translation added a hurdle that would confuse the unaware. In order to approximate Neri's intended composition under the prevailing avoirdupois system, Merrett's "ingenious" (as he called them) British readers would need to decrease by 1/5 quantities specified in pounds, and increase ounces by 1/15.

This post first appeared on 18 September 2013.

Monday, June 5, 2017

Thévenot in India

Antique gold Arsi finger ring,
 Rajasthan India.
This is the third and final installment of a series that has followed seventeenth century French tourist Jean de Thévenot from Europe to the Levant and then into Syria. Now he travels to India. We have specifically looked into his diary with an eye toward passages that mention glass or glassmaking. While our intrepid traveler had no special connection to this art, he did possess a keen, inquisitive mind; collectively, his observations about glass give us a glimpse into the state of affairs in the Middle and Far East in the mid 1600s. 


We left off with Thévenot as he headed up the Tigris River toward Baghdad, in the autumn of 1663. While he was anxious to see Mughal India, actually getting there presented some difficulty due to hostilities between the Dutch, British and Portuguese, which extended to their trade operations around the world. After a first attempt was aborted, he made a strategic retreat to Isfahan and bided some time with shorter excursions from there. Finally, in the autumn of 1665 he booked passage on the originally English ship “Hopewell” recently purchased by an Armenian trader and captained by an Italian. [1] The ship departed from Basra and made port at Surat, India in January of 1666.

The city of Agra is in the Northwestern part of India, a thousand kilometers from Surat and the coast; it is known most famously as the home the Taj Mahal. When Thévenot passed through, he noted of the women “They wear a great many [rings], and as they love to see themselves, they have always one with a looking-glass set in it, instead of a stone, which is an inch in diameter.” [2]

These rings, set with a mirror, are known as “arsi” and can still be found in some areas around the country. Indeed, Sharma and Seth note in their 1997 book on contemporary regional costumes and ornaments that mirror rings were popular in the northern most reaches of India. In the western Himalayas at Chamba and as throughout India, they are still worn today. “Arsi or arsu means a mirror. An ornament with this name is a ring fitted with a round mirror or a looking-glass. It is usually worn on the thumb of the right hand. With the help of arsi, the hill woman can look at herself in the mirror and feel assured of her beauty in such places like fairs and festivals. Thus she can stealthily have a glance in the mirror whenever she desires, even in the company of males without feeling awkward.” [3]

Another reference states that in the seventeenth century arsi rings were worn by both men as well as women, but I have been unable to confirm this. In any event, they appear to have been wildly popular. On an earlier expedition through Aleppo, Syria, Thévenot observed “five or six hundred cases of [mirrored] glass” being shipped down the Euphrates River. When he expressed surprise at the rough handling, he was told “that it mattered not, though it were all broken into pieces, because the Indian men and women buy it only to have little pieces set in rings, which serve them for looking-glasses to see themselves in.” [4]

Thévenot’s first landing was in Surat on the west coast of India, about 300km north of Mumbai. In 1688, Captain Alexander Hamilton landed at the same port and recorded, “The [Muslim] women wear gold rings on their fingers, and sometimes one on their thumbs, with a small looking-glass set in it.” [5] Other travelers also noticed the rings:  In the 1660’s Frenchman Souchu de Rennefort observed similarly, “They wear also many [rings] on their fingers, and among the rest, one with a small looking-glass in it, which serves them to contemplate themselves.” [6]

The earliest account I have been able to find recounts not a glass mirror but one of metal. On 25 September 1637, ambassadors from the Danish duke of Holstein were visiting the King of Persia and were entertained by six dancing women from India. The women were accompanied by their husbands who played musical instruments. “Some of them had bracelets of pearl, others of silver, but they had all rings on their fingers, and among the rest, they had upon the thumb, upon which in the place where the stone should be, there was a piece of steel, about the bigness of a crown-piece of silver, and so well polished that it served them for a looking-glass.” [7]

As these accounts suggest, vanity may well have been the motivation for the popularity of the arsi rings, but it is worth noting that mirrors did play a role in some religious practices. Wikipedia states, “The Nizhal Thangals and Pathis have, in their sanctuary, a mirror to reflect the images [of] worshippers. […] The mirror's placement symbolizes that God is inside oneself and it is of no use to seek God elsewhere.” [8] In some Muslim weddings of Southern India, a traditional ritual is called ‘Arsi-Mushaf’ or “the mirror ring and the Quran,” in which the newly betrothed observe each other through a mirror.

Thévenot stayed in India for over a year and crossed the country to its East Coast. Finally, he returned to Surat, sailed to Persia and traveled north back to Shiraz. He spent the summer of 1667 at Isfahan, after suffering an accidental gunshot wound. In the autumn, he started north for Tabriz, but died on the way at Meyaneh on 28 November 1667.


[1] Armenians in Asian Trade in the Early Modern Era, ed. Sushil; Kevonian Chaudhury (Keram). (France: Les Editions de la MSH, 2008) p. 106.
[2]Jean de Thévenot: The Travels Of Monsieur De Thévenot Into The Levant: In Three ..., Volume 3
 (London: Archibald Lovell Faithorne, 1687)v. 3,  p. 38.
[3] Kamal Prashad Sharma, Surinder Mohan Seth: Costumes and Ornaments of Chamba (New Delhi: Indus Publishing,1997), p.113
[4] Jean de Thévenot: “The Travels of Monsieur Thévenot Into The Levant” (London: H. Clark, 1687), v.2, p.40.
[5] Alexander Hamilton, A New Account of the East Indies: Giving an Exact and Copious ..., Volume 1(London: C. Hitch; and A. Millar, 1744) v. 1, p. 165
[6] Gabriel Dellon, Jodocus Crull, Souchu de Rennefort: A voyage to the East-Indies: giving an account of the isles of Madagascar (London: D. Browne, 1698) p. 25
[7] Adam Olearius, John Davies, Johann Albrecht von Mandelslo: The Voyages & Travels of the Ambassadors from the Duke of Holstein, to the ... (London: Thomas Dring, and John Starkey, 1662), p.277


[8] Wikipedia: https://en.wikipedia.org/wiki/Ayyavazhi_rituals

Friday, June 2, 2017

Thévenot Continues East

Stained glass windows of the Nasir al-Mulk 'Pink Mosque', Shiraz, Iran
Photo by Domiri Mohammad Reza Ganji.
(Click to enlarge)
Previously, we followed the progress of seventeenth century tourist Jean de Thévenot, noting his comments about glass as he traveled. He sailed from Rome to Malta to Constantinople to Egypt. He then continued overland through Syria and sailed down the Euphrates River toward the Persian Gulf.  At Basra he turned around and headed north, picking up the Tigris River to Baghdad where he continued eastward to Persia. In Isfahan he described numerous species of plants, animals and insects. Further south he took note of a city where glassmaking captured his attention:


The people of Schiras [Shiraz, Iran] are very witty and the city hath given birth to most of the best poets of Persia. There is much glass made there, and several glass-shops are in town, though they work not constantly in their glass-houses, but let the fire go out after they have employed a certain quantity of materials. They make their glass of a white stone, almost as hard as marble, which they get in a hill four days journey from Schiraz and it is very clear: especially they make great bottles as clear and delicate as in any other place in the world; but it is wonderfully strange how they can blow the great bottles they call ‘Caraba,’ which are as thick as one finger and hold nearly thirty quarts of wine; these bottles are covered with the straw of canes. [1]

Preceding Thévenot in Shiraz by a number of years (1627) was the British traveler, Sir Thomas Herbert, who stated that there was “…no part of the Orient showing better or richer wine.” [2] The mutually beneficial association between the production of wine and glass is one that appears in numerous locations throughout history. That both crafts should occur here, at the center of activity for this region’s premier vineyards should be no surprise. 

The region’s ‘Shirazi’ wines have been connected by various legends to the French Rhone variety now known as ‘Shiraz,’ but the vineyards in Iran are now defunct, and no definite conclusions have been reached, except that if a kinship exists, it is a very ancient one. In other quarters, Marco Polo mentioned Persian wines [3] and Omar Khayyam praised them throughout his Rubaiyat. [4]

At the same time that Thévenot passed through the region, so did fellow Parisian Jean Chardin (Sir John Chardin) who spent about eighteen months visiting (1666-7). It is unknown if the two travelers met. In his own published diary Chardin stated  “The art of glass-making; there are glass houses all over Persia, but most of the glass is full of flaws […] The glass of Chiras [Shiraz] is the finest in the country” and he went on to say that “Moreover, the art of glass-making was brought into Persia within these four score [80] years. A beggarly and covetous Italian taught it at Chiras for the sum of fifty crowns.” [5]

This last passage is often quoted in reference books without comment, to the point that it has become quite famous. At the risk of stating the obvious, the notion that one man, a foreigner, down on his luck, could single handedly bootstrap an entire industry that would fully mature throughout Persia in eighty years is absurd on its face. Beyond that, it is something of an insult to a culture that current scholarship credits with key developments in the invention of glass more than five thousand years ago. [6] Chardin’s condescendence toward Persian artisans and craft in general is well demonstrated throughout his book. His claim is plain enough, however if we want to be charitable, we could speculate that he misunderstood his source, who actually told him that the Italian was responsible for showing European style glassmaking to a well established technical community in Shiraz. Historian Stefano Carboni identifies a fifteenth century downturn and says “in Iran the industry was revived with the help of European, mostly Venetian, craftsmen in Isfahan and Shiraz from the seventeenth century.” [7]

[1] Thévenot v.2, p. 125, 126
[2] Thomas Herbert  “A Relation of Some Yeares Travaile, Begunne Anno 1626.” (London: Stansby and Bloome, 1634), p. 133.
 By Thomas Herbert   also see http://www.saddleflasks.com  “An extensive reference site devoted to Late Persian glass.”
[3] By Marco Polo, “The travels of Marco Polo, the Venetian,” trans. by William Marsden (London: J.M. Dent, 1926), p. 41 (bk.1 ch. 15).
[4] Omar Khayyam, “Rubaiyat of Omar Khayyam” trans. by Edward Fitzgerald (Boston: Branden Books, 1989), for example, stanzas VI, XI, XII, XLI, LVI.
[5] John Chardin “Sir John Chardin's Travels in Persia” (New York: Cosimo, 2010) p.275  (abridged English translation of 1724 original).
[6] For instance, see  https://en.wikipedia.org/wiki/History_of_glass http://www.iranicaonline.org/articles/glass ,  https://en.wikipedia.org/wiki/Sasanian_glass .
[7]  Stefano Carboni, “Glassware” in Medieval Islamic Civilization: An Encyclopedia edited by Josef W. Meri (New York, Routledge, 2005) v. 1, p. 298.