In Greece during the 3rd century B.C. lived one of the greatest mathematicians in history, Archimedes. His most famous discovery was the principle of buoyancy: that an object immersed in a fluid is buoyed up by a force equal to the weight it displaces. It is said he made this discovery while taking a bath. In his excitement he ran naked through the streets shouting "Eureka!" ("I have found it"). His principle that an object tends to remain afloat in a liquid applies as well to its capacity to rise in air or gas, and was applied some 2000 years later in the perfection of the hot air balloon. When his city fell to the Romans Archimedes was killed, it is said, while drawing geometric patterns in the sand. When in turn the Roman Empire fell in 500 A.D. their great libraries in Alexandria, Egypt were sacked and vandalized. The discoveries of Archimedes and many others from Greek, Roman, Jewish and Arab civilizations were lost for a thousand years. The Dark Ages, ruled by superstition rather than intellect, descended.

One of the first theorists of flight was Roger Bacon, a 13th century English scholar. Bacon had an interest far in advance of his times in the accurate observation of phenomena. His studies in alchemy, whose aim many considered to be the transmutation of base metals into gold, foreshadowed physics, in which one element is transformed into another through nuclear reaction. Bacon's contemporaries considered him a magician, although today we consider him more a scientist than shaman. Many discoveries have been attributed to him, including the invention of gunpowder and the first examination of cells through a microscope, but much doubt has been cast on the authenticity of such claims.

It is a fact, however, that in 1250 Bacon wrote The Wonderful Power of Art and Nature , in which he described a flying machine. "Such a machine must be a large hollow globe of copper or other suitable metal, wrought extremely thin in order to have it as light as possible. It must then be filled with ethereal air or liquid fire and launched from some elevated point into the atmosphere, where it will float like a vessel upon the water." This is distinctly different than the harnessing of birds by Kai Kaiwus. But how did one travel into the sky to obtain "ethereal air?" And who but a magician could create "liquid fire?" More discoveries were needed to advance the technology of flight. Progress was certainly hindered in that Bacon's book was not published until 1542.

The dawning of the Renaissance in 15th century Italy stimulated a renewed interest in art, literature and science that spread throughout Europe over the next two centuries. The invention of movable type by Johann Gutenberg in 1455 greatly increased the availability of ancient texts and accelerated the communication of new ideas. Compared to the electronic immediacy of today, information appears to have been gathered in isolation and slowly shared. But the transformation of attitude, from enforced ignorance to open inquiry and exchange, was remarkable.

In 1648 John Wilkins, a founding member of the Royal Society of London for Improving Natural Knowledge, was able to posit through scientific principles what Roger Bacon had conjectured: the "ethereal air" of the upper atmosphere was of lower density than that of the lower atmosphere, therefore a container filled with less dense air would rise. And in 1680 the Italian mathematician and physiologist Giovanni Alfonso Borelli published Concerning Animal Motion, in which he proved that humans did not have the muscle power to emulate birds.

In 1670 Francesco de Lana de Terze, a Jesuit priest who taught literature and science at a convent in Rome, elaborated upon Bacon's ideas in his Essay on New Inventions. De Lana had studied atmospheric pressure and conducted a number of experiments on the subject. Utilizing the invention of the air pump some 20 years earlier, he proposed a "flying-boat" propelled by a sail and lifted by 4 copper spheres from which all the air had been pumped. A near-vacuum seemed more practical than attempting to trap ethereal air or liquid fire. The copper spheres, however, posed a problem which de Lana could not solve. If the globes were made thin enough to become lighter than air, they would collapse under atmospheric pressure as the air from within was extracted. If they were constructed heavier than air, they would not lift at all. Roger Bacon's proposal of a low density gas would prove to be correct, but de Lana is credited as the first person to design a lighter-than-air craft based on definite scientific principles.

Only recently, when a yellowing parchment document stored at the University of Portugal was translated, has the achievement of Bartolomeo Laurenco de Gusmao come to light. Gusmao, a Brazilian priest, was granted an audience with the king in 1709. He lit a fire in a small model which promptly lifted into the air, abruptly hit some curtains, and set fire to them as well as nearby furniture. The king was impressed enough by the ascent to disregard the ensuing accident, as well he should. He had witnessed what is now considered by many to be the first lighter-than-air flying machine in history.

The discovery of Gusmao's earlier experiment takes nothing away from the remarkable achievements of two brothers in France. Gusmao had used a model, and his limited success was scarcely documented and witnessed by only a handful of people. The French brothers used a full-scale piloted vehicle, repeated the feat with increasing success and did so before huge crowds.

As so often happens, the inspiration for their discovery was based on a common observation. The crucial difference is that where others thought no further, they had a flash of insight. In the Spring of 1783 Joseph Michel and Jacques Etienne Montgolfier, who owned a paper mill near Lyon, noticed a shirt that had been hung out to dry over a fire. It billowed upward and looked as if it had inflated. They studied the ascending force of the smoke and came up with the idea that if they enclosed in an "envelope" what they considered to be a special gas, the bag would rise from the ground. They experimented with paper bags from their mill over fires made from varying materials. Coining the term "Montgolfier gas" the smoky air created from a fire of straw and wool, they inflated larger and larger balloons.

On September 19th, 1783 the Montgolfiers put a sheep, a duck, and a rooster in a tethered balloon to determine if animals could survive at heights. The experiment occurred at the palace at Versailles and was witnessed by King Louis XVI, his court, and some 130,000 astonished spectators. The no doubt terrified "passengers" were in flight for 8 minutes and traveled almost 2 miles. Two astronomers calculated the balloon's altitude to be 1700 feet. The king was delighted and demanded more of this wonderful amusement. On October 15th Francois Pilatre de Rozier, a professor of chemistry, went up in a Montgolfier balloon, again tethered. The balloon was an oval shape about 49 feet wide and 78 feet high. De Rozier ascended to a height of 85 feet. This event is considered to be the first manned lighter-than-air flight.

On November 21st, in the same Montgolfier balloon that had taken the animals up, the two-person crew of Rozier and the Marquis d'Arlandes made the first free flight not tethered to the ground. They traveled more than 5 miles across the city of Paris and reached a height of 3000 feet. D'Arlandes was fairly taken with the view, doffing his hat to the open-mouthed spectators below. At one point he was so distracted he forgot to add straw to the fire to keep the balloon up. Rozier reminded him, "You are doing nothing and the balloon is scarcely rising a fathom." A few minutes later d'Arlandes noticed that a fire was burning holes in the balloon fabric and threatening the cords that attached the gallery in which they rode: two of the lines had already parted. D'Arlandes quickly grabbed a sponge and a bucket of water brought along for just such an emergency, and managed to extinguish the fire. After that, the aeronauts found themselves dropping uncomfortably close to the Paris rooftops. They threw more straw on the brazier and rose to a more comfortable altitude. 25 minutes after take-off they allowed the fire to subside and landed gently between two mill houses. D'Arlandes wrote later how surprised he was by the silence and the absence of movement among the spectators. Apparently (and rightfully) they were stunned. Practical air travel had begun.

In the same month Jacques Alexander Cˇsar Charles, member of the French Academy of Sciences, made a flight in a balloon filled with hydrogen, which is one fourteenth the weight of air. Henry Cavendish had discovered hydrogen in 1766, but this was the first time anyone had used it in a large balloon. Actually, Charles had the misconception that the Montgolfiers had been filling their balloons with hydrogen instead of hot air, i.e. "Montgolfier gas." This mistake led to the creation of a different kind of aerostat and furthered the progress of lighter-than-air craft. The hot air balloon, with its requirement of an open fire, was rather dangerous. Hydrogen, although inflammable (recall the "liquid fire" of Roger Bacon) was completely enclosed in the balloon before liftoff. In fact the free balloon of today, though it uses the non combustible element helium in place of hydrogen, is similar in all its essentials to the balloon design of Charles.

The Charles balloon got up to 3000 feet and traveled about 16 miles in 45 minutes. The flight was successful, but so unfamiliar that it inspired terror. As Charles landed just outside Paris the local peasants, thinking that the "monster" was sent by vengeful neighbors, hurled rocks at it and destroyed the balloon. A Paris journal describes the event. "The creature, shaking and bounding, dodged the first blows. Finally, however, it received a mortal wound, and collapsed with a long sigh." A village man stuck his knife into the balloon and when the victors had decided it was dead they tied it to a horse and dragged it to the village. To prevent further incidents the government issued a proclamation stating that a balloon "is only a machine, made of taffetas, that will someday prove serviceable to the wants of society." For his next flight Charles had a new balloon and 400,000 spectators. Parisians were so enthusiastic about this new phenomenon that hundreds helped to finance the building of the balloon by paying one crown apiece for the privilege of a "close-up view" of the anticipated take-off from a special enclosure. Benjamin Franklin, the 77 year old scientist-philosopher and diplomatic representative to France from the newly formed United States of America, was among the many who contributed to and saw the flight.

The balloon craze broke out across Europe. Within a year the public was startled and delighted by the sight of balloons going up in England, Scotland and Italy. Ten years after Ben Franklin's experience in Paris the first balloon ride occurred (coincidentally?) in Philadelphia, Pennsylvania. Shortly after, as mentioned, the first successful parachute jump was made from a balloon. An industry quickly sprung up, with professional "pilots" touring the countryside with paying passengers on board. The thrill of being airborne swept through civilization.

In 1794, Jean Pierre Coutelle used balloons in France for military purposes at the battles of Maubeuge, Charleroi and Fleurus. He made two 4-hour observation ascents. The purpose of the ascents was two-fold: to lower the enemy's morale and to observe where the artillery fire was so that battle strategy could be refined.

But the restrictions of balloon flight were clear. The accomplishment was strictly that of achieving lift and descent, and even that was precarious, as the first crossing of the English Channel in 1785 colorfully illustrates. Jean-Pierre Blanchard had designed the balloon and a two-person gallery shaped like a boat. Blanchard and an American, Dr. John Jeffries, filled the gallery with food, brandy, flags, bags of ballast, oars, cork jackets and self-promoting leaflets. Using the gentle westerly blowing breezes they began their flight towards France, but as the temperature over the waters decreased the balloon began to lose altitude. By the time they were two-thirds of the distance across the Channel they had jettisoned nearly all of the provisions but were still descending. Thinking they would be in the waters at any moment they stripped off their clothing and donned the jackets. At that moment the balloon rose slightly and the journey continued. About two hours after they had begun their flight they spied with relief the coast of France, but their troubles were not done. The balloon again began to descend over a dense forest, and fearing a crash they tossed over the cork jackets. Recalling that they had drunk a lot of liquid before the flight, Jeffries suggested they empty their bladders. Two containers were rapidly filled and thrown over the side and into the woods. This slight reduction of weight allowed them to travel a little further to a clearing where they landed, according to Blanchard, "Nearly as naked as the trees." The only objects left in the gallery were a bottle of brandy and a packet of letters. The first airmail delivery was thus accomplished.

Adding to such adventures in altitude, there existed no ability to power or control direction. The wind alone determined a balloon's flight and when completed, one returned to the point of departure by land. The shortcomings of the balloon were recognized as quickly as its initial success, and minds set to work to add functionality. In 1784 Jean Baptiste Marie Meusnier, a general in the French army, designed the first powered airship, or dirigible. The balloon was elliptical, like a cigar, to reduce air resistance as it moved from the power derived from three propellers. Unfortunately, the propellers would be cranked by human hands.

It was not until 1852 that Henri Giffard, a French engineer, flew in a steam powered balloon - the first working dirigible. 144 feet long and 39 feet in diameter, inflated with 88,000 cubic feet of coal gas, it flew from Paris to Trappe at an average speed of 6.7 mph. Although control was minimal and the motor too heavy, this event was a great advance for aeronautics. In 1872 Paul Haenlein raised the speed to 10 mph with an engine fed by coal gas from an envelope of the balloon. The first fully controllable airship, steerable back to its starting point regardless of wind, was built in 1884 by the team of Charles Renard and A.C. Krebs. It used an electrical power plant and achieved 14 1/2 mph.

In 1898 Alberto Santos-Dumont, a wealthy and charismatic Brazilian, was the first to use the recently developed internal combustion engine. He became internationally famous in 1901 when he won 100,000 francs by departing from St. Cloud, circling the Eiffel Tower, and completing the nine mile journey within the 30 minute time limit (with 29 seconds to spare). Santos-Dumont donated 75,000 francs to the poor of Paris and divided the rest among the workers who helped build his airship. He did much to popularize the dirigible by taking paying passengers on sight-seeing tours around Paris before docking at the Aero Club for lunch. His dirigibles were small and used only for demonstrations, and he is best known as a pilot rather than designer, though he did turn his attention to heavier-than-air designs.

It was a retired German Cavalry officer whose diligence was rewarded by the development of the most successful airship to this day. Ferdinand von Zeppelin made his first flight in 1900. The dirigible was powered by an internal combustion engine that achieved 18 mph. It had a rigid metal frame that allow sustained flight even if gas or power was lost. The gas itself was separated into compartments evenly distributed, which prevented catastrophe should one compartment fail. The air space between the cells and the outer covering acted as a temperature control that improved gas efficiency and therefore would sustain longer flights.

But like those before him, "The Crazy Count," as he was called by his detractors, had to rely on his own vision of the future to overcome massive skepticism by the public and his government. By 1910 his airships were providing scheduled service between German cities, and when war was declared in 1914 the military appropriated the existing dirigibles and contracted for more. Once considered impractical, black painted Zeppelins became a terrifying sight over London as they dropped their bombs.

Upon conclusion of the war the Zeppelin design was enhanced and copied throughout the world, culminating in the Graf Zeppelin. This airship was more than three times the length of a Boeing 747, had a cruising speed of 68 mph, and made regular flights from Europe to South America in which two dozen passengers had their own suites and dined from an ever-changing menu prepared by famous chefs. The dirigible was clearly the leader in commercial air travel.

But as we know, lighter-than-air travel has been unable to compete overall with the heavier-than-air constructions of the 20th century. We have to return to the study of birds to pick up the thread of discoveries that lead to today's designs. But instead of pursuing wings that flap, studies were made of wings at rest.

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