CHAPTER ONE
Nature's Nearly Perfect Product

In the early 1660s, Robert Hooke, the Curator of Experiments for the newly founded Royal Society, a group leading the scientific revolution in England, labored for hours over his new, exciting instrument. It was called a microscope, and just as Galileo had opened new worlds by looking far into space in the early 1600s with a telescope, Hooke was now discovering new worlds in the opposite direction, minute ones that had previously been too small for the human eye to see.

Hooke, a physically unattractive and often unpleasant person who collected enemies as easily as friends, would later be called England's Leonardo da Vinci because of the breadth of his scholarship. After graduating from Oxford in 1663, he worked with scientist Robert Boyle developing the theory of gases that bears his collaborator's name. He also worked with court architect Sir Christopher Wren in the reconstruction of London after the Great Fire of 1666 and on such historic projects as rebuilding St. Paul's Cathedral and the Royal Observatory at Greenwich, where world time starts. In addition, Hooke discovered the spring control of the balance wheel for watches, which finally made accurate time-telling possible, the reflecting telescope, and the pedometer.

Through his microscope, which had a fifty-times magnification, far more than others at the time, Hooke studied some of the most basic natural objects around him: fleas, sponges, bird feathers, and more. Observation Eighteen, as he carefully noted it, particularly fascinated him. It was a piece of cork, a product that had been around for centuries but was only recently being used widespread as a stopper in bottles. He first selected what he described as a "good clear piece" and then with a penknife "sharpened as keen as a razor" cut off a slice to leave "the surface exceedingly smooth." Then he sliced an "exceedingly thin piece" and placed it on a black plate so that the pale cork would stand out in contrast. As he peered at the material through his lens, the cork seemed to take on magical characteristics. He later wrote, "I could exceeding plainly perceive it to be all perforated and porous, much like a honey-comb."

The structure of the piece reminded Hooke of cells where monks in a monastery slept and prayed, and so he called the boxes cells, coining the term since given to the building blocks of all living things. He went on to calculate with awe that there must be "twelve hundred million" cells in a cubic inch of cork. Swept away with the excitement of the moment, Hooke later wrote, "These pores, or cells, were not very deep…. I no sooner discerned these (which were indeed the first microscopical pores I ever saw, and perhaps that were ever seen, for I had not met with any writer or person that had made any mention of them before this) but me thought I had with the discovery of them presently hinted to me the true and intelligible reason of all the phenomena of cork."

In 1665, when Hooke was twenty-nine, the Royal Society published his Micrographia, a book recounting his experiments, which became a best seller and laid the foundation for using microscopes in biology and medicine. Hooke was also an artist and drew detailed illustrations for the book of what he had seen through his microscope, including the cross section of a cork that indeed resembled a honeycomb. One of his book's early readers was English diarist Samuel Pepys. After working at his job as Secretary to the Admiralty Commission until past midnight on January 21, 1665, Pepys stayed up at home until two in the morning reading what he called "the most ingenious book that ever I read in my life."

People since then have been just as fascinated by cork as Robert Hooke was the day he saw it for the first time under a microscope, for there is no other product in nature quite like it. Later scientists with better microscopes have learned a lot more about cork. The cells that Hooke first saw are fourteen-sided, or tetrakaidecahedrons, so tightly joined together that there is no empty space between them. The cell walls are made up of five layers of material: two outer ones are cellulose; the central one has a woody quality and provides the structure; two inner ones are impermeable. Suberin, a complex fatty acid, is the basic material in cork. Hooke was off only a little on the number of cells; a wine cork contains some 800 million.

Cork cells are filled with microscopic amounts of air. Nearly 90 percent of cork's volume is made up of those tiny, trapped air pockets, and that gives the product its unique buoyancy and compressibility. Air gets into a bottle closed with a cork, but three and a half centuries after Hooke, scientists still don't know how that happens. Some believe it comes through or around the cork, but others think compressed cork cells release it.

Because of the air pockets, cork is among the lightest of all solid substances, which is why it has been used for millennia as floats. If a cork is pushed in one direction, it does not bulge out in another, unlike rubber or plastic. Cork simply contracts. But then it also quickly returns to its original shape because of its unique elastic memory. Even if cork is strongly compacted, it will return to 85 percent of its original volume almost immediately and to 98 percent after a day. In addition, cork can withstand extreme high and low temperatures, but does not conduct either heat or cold. It also absorbs vibration and is extremely long lasting. Cork floors or cork bottle stoppers are good for decades. In 1956, twenty bottles of vintage 1789 wine were found with corks in them in a French cave. The corks were still in fine condition. The wine was slightly brown and obviously overaged, but still well preserved.

Cork comes from the cork oak tree, known to scientists as Quercus suber. The tree has two layers of bark. The inner one is alive, while the outer one has died. As successive layers die, the outer bark becomes thicker. This outer layer can be harvested about every decade without doing damage to the inner tree.

Although attempts have been made to cultivate cork elsewhere in the world, it still grows mainly around the western-Mediterranean region. It is thought that cork was originally harvested around the whole basin, but in more recent times it has been grown primarily in the western part on both the northern and southern shores—from Italy to Portugal in the north and from Tunisia to Morocco in the south. The two major cork-producing countries are Portugal and Spain, accounting for more than 80 percent of total world production.

No one knows exactly when the first person put the first cork in a wine container. Archaeologist Patrick McGovern of the University of Pennsylvania and author of Ancient Wine is a leading expert on the history of winemaking. According to his research, the Chinese made a product that consisted of wine, beer, honey, and other products about nine thousand years ago. Western wine was first produced about a millennium later somewhere in the mountainous area stretching from eastern Turkey across the Taurus, Caucasus, and Zagros mountains to northern Iran. The first wine was probably made by accident when bunches of grapes were left too long in a container and mysteriously turned into a light, fruity wine. McGovern labels that Stone Age Beaujolais Nouveau, speculating that it was made by carbonic maceration much like the short-lived, but popular, drink now made each fall in France.

The Greek historian Thucydides wrote, "The peoples of the Mediterranean began to emerge from barbarism when they learned to cultivate the olive and the vine." The discovery of pottery in roughly 6000 BC made it possible for people to store wine for the first time, and so the history of pottery coincides with that of wine. Pottery also made wine trade possible. The vast majority of trade in ancient times was in just three products: wine, grain, and olives or olive oil.

Winemakers soon learned that air is the enemy of wine. While some air is crucial to get fermentation started and turn the sugar in grape juice into alcohol, the resulting wine will become vinegar if it stays in contact with air. Ethanol, the intoxicating ingredient in wine, in the presence of the bacterium Acetobacter aceti turns into acetic acid, which gives vinegar its astringent smell and taste. The English word vinegar comes from the French vinaigre, which literally means "sour wine."

Thus winemaking for millennia was an endless struggle to halt the natural process of wine turning into vinegar. Vintners soon developed containers that not only held wine but also kept out most air. The most popular were amphoras made of reddish brown clay, which carried a variety of both dry and liquid products. They remained in use for nearly six thousand years and came in all sizes, with the most popular being about two to three feet high and containing between eight and sixteen gallons of liquid. The larger ones weighed about 130 pounds when full of wine.

Amphoras had two handles and a pointed end, which served as a third handle that helped in carrying and pouring them. They also had long, narrow necks that made it hard for air to enter the container, but during winemaking the amphora's neck had to be left at least partially open so that carbon dioxide, a by-product of fermentation, could escape. Fermentation was a haphazard development that early winemakers could neither understand nor control. They learned from bad experiences that if they sealed amphoras too tight, pressure built up, and the vessels exploded. Early winemakers learned that once fermentation ended, though, they had to seal amphoras to keep out air. This was often done by putting a glob of wet clay onto the top of the neck. Many early winemakers also stored amphoras partly in the ground to keep the contents cooler and thereby slow the change to vinegar.

By 3000 BC, Egypt, the superpower of its day, was the center of wine. At first the Egyptians imported wine, probably from southern Palestine, but eventually they planted their own vines and took the rudimentary craft they inherited to a much higher level. Egyptian methods of making wine were clearly described on fresco paintings that still exist today. In addition, many amphoras dating back to 3000 BC have survived.

By the golden age of Egypt, about 1500 BC, winemaking had become fairly sophisticated. Vintners now had a much better mastery of the process, especially the crucial task of keeping out air. A fresco in a tomb in Thebes from 1400 BC gives a colorful picture of contemporary viticulture. Along the back wall of the winery are rows of amphoras at various stages of winemaking. Some of the vessels are open and are probably still undergoing early fermentation. Above them are jugs with the neck containing straw or grass to let off carbon dioxide while keeping air out, a process similar to the one used today in wineries around the world. Off to the side are rows and rows of wine in amphoras with flat or cylindrical tops on them, where fermentation has been completed.

Copyright © 2007 by George M. Taber.