9th Class

"Hair brings one's self-image into focus; it is vanity's proving ground" Shana Alexander, Journalist Hair salons were exclusively for rich women of the 1890s, and it was in that decade that French hairdresser Alexandre Godefroy introduced the first blow-drying hair dryers to put in his salon. His makeshift dryer was simply a bonnet attached to a flexible chimney stuck onto a gas stove. It is hydrogen bonds that determine whether your hair looks like you have been dragged through a hedge backward or just walked out of a shampoo ad. Blow-dried hair generally looks better because it accelerates the temporary hydrogen bonds that reside in each strand of hair, allowing better control of shape and style. Curlers, straighteners, and all other hair appliances that work by heating the hair to change its shape are simply controlling the hydrogen bonding. Strong, hydrogen bonds are susceptible to humidity and completely disappear when more...

"Technical progress is made by integration, not differentiation." Max M. Munk, physicist and mathematician Early airplane engineers based their flying machines on the flight of birds. It soon became clear, however, that this method was limited. When a bird is in flight, air flows over its wings, and engineers realized that the flow of air over an airplane's wings would need to be simulated in order to uncover the secrets of flight. Early simulation methods included the whirling arm in which a wing was attached to a pole and rotated. Shortly after, Frank Wenham (1824-1908) designed a crude wind tunnel in which a fan channeled air down a tube.-This produced a controlled airflow, and harnessing this led to the first variable- density wind tunnel of Max Munk (1890-1986). Munk moved from Germany to the United States in 1920 to work for the National Advisory Committee for Aeronautics. He decided to more...

"My hydraulic brakes stop on a dime—and with change left over." Malcolm Lougheed, aviation and auto engineer Before the invention of hydraulic brakes, various systems of levers and pads were developed, but their main drawback was that they needed regular adjustment to maintain equal braking on all wheels. Hydraulic brakes, invented in 1918 by Malcolm Lougheed, addressed this problem and gave much more responsive braking. Hydraulic brakes work by having a series of pistons connected to the brake pedal and the brake pads themselves. These are all interconnected by a central "reservoir" of non-compressible fluid, initially a mix of water and alcohol. The differences in diameter of the pistons means that the same pressure inside the system magnifies the force applied to the brake pedal. This greater force allowed the brakes to be applied much more firmly and so bring cars to a quicker halt. The system was taken up more...

In the fall of 1882 part of New York's lower Manhattan flipped the switch on what seemed to many to be an unholy miracle—a centralized, commercial electrical system providing both power and light. The power station at its hub stood on Pearl Street, in the capital's financial district. This was the first permanent system of its kind. It used direct (as opposed to alternating) current and 3,000 electric lamps. The man behind it was the irrepressible multiple inventor and "wizard of Menio Park Thomas A. Edison (1847-1931). In the late 1870s one of the greatest quests of practical science had been to replace large, powerful electric arc lamps, which overheated easily, with smaller, safer lights. Edison's Electric Light Company, backed by a brace of prominent financiers including J. P. Morgan and the Vanderbilts, set about creating a parallel circuit where the current was divided between a string of small lamps more...

Before 1878, the separation of cream from milk occurred through nothing more than the force of gravity. This process took time and was also inefficient since it limited the amount of cream that could be processed from the milk. Cream is formed when the lighter fat molecules of cream rise to the top of the milk through its heavier water-based fraction. This process happens naturally in raw milk when it is left to settle for a period of at least twenty-four hours. Cream can then be skimmed off or the milk can be drained from underneath, leaving only the cream behind. Fortunately, help was at hand for the dairy industry. Stockholm Institute of Technology graduate Carl Gustaf de Laval (1845-1913) had been experimenting with centrifugal force as a way of separating fluids. In 1878 he invented a steam-driven device that spun raw-milk sample at 4,000 revolutions per impute. Under the more...

"Results! Why man, I have gotten a lot of results. I know several.....thousand things that won't work." Thomas Edison American inventor Thomas Edison (1847-1931) filed more than 1,000 patents during his lifetime. He fell into- the world of telegraphy after he saved a three-year- old boy from being struck by a train. To repay his good deed the child's father agreed to teach him railroad telegraphy. Edison quickly picked up the skill and went to work as a telegraph operator at Western Union. Although he was eventually fired from his job, Edison's interest in telegraphy was born. At the time, one wire could only send one telegram in one direction at a time; consequently sending and receiving messages was a slow process. Edison perfected the existing system to one signal in one direction and one signal in the other, and he called this duplex telegraphy. He later made it possible more...

"The practical success of an idea ...is dependent on the attitude of its contemporaries." Nikola Tesla One of the most important inventors in history, Nikola Tesla, was born in 1856 in Smiljan, Croatia. His inventions would revolutionize our world. Among his almost 300 patents were wireless communication, the alternating current, and the induction motor. Tesla built the first working induction motor in 1883. Michael Faraday had demonstrated an electric motor in 1821 and Zenobe Gramme went on to invent the modern direct current motor in 1873, but it is Tesla's motor that most of our household appliances rely on. The induction motor works using alternating current rather than direct current. It has a simple design and is significantly less expensive to manufacture than the direct current motors. It also has fewer parts to wear out and is thus more reliable. The induction motor does more than run your vacuum cleaner. more...

Sulfur is an important precursor to many industrial processes. Much of it goes into making sulfuric acid, a common reactant and a component of fertilizer. In the nineteenth century, Sicily dominated the production of this element. Deposits were found in the United States, too—notably in Louisiana and Texas—but they were much deeper and more difficult to mine. It may not have been gold, but unlocking this yellow substance could be a deeply profitable business. One man had the answer, and from it derived the process that now bears his name. German-born Herman Frasch (1851-1914) settled in the United States and made a name for himself removing unwanted sulfur from petroleum. In the 1890s sulfur itself became the focus of his attention, and he sought a way to mine the deep-set mineral. His solution was to bore a drill hole down to the layer containing sulfur. An arrangement of three concentric more...

As a conduit for the output of all electronically created sound, the loudspeaker is one of the most significant inventions of the past 150 years. Indeed, in one form or another loudspeakers have been at the heart of much of the technology that has since emerged—from telephone, radio, and television to hi-fi music systems. It was Alexander Graham Bell (1847-1922) who patented the first electrical loudspeaker in 1876, as part of his telephone system. In conjunction with his assistant, Thomas A. Watson, Bell created a simple design. A drum was covered with a tightly stretched goldbeater's skin (diaphragm) and a magnetized free- floating armature was placed at its center. The armature was able to vibrate against the skin and responded to changes in a magnetic field. This device was connected to Bell's "liquid" transmitter into which he uttered words that were heard clearly by his assistant in the next room. more...

"Speed has never killed anyone, suddenly becoming stationary... That's what gets you" Jeremy Clarkson, motoring broadcaster From time to time a talented inventor comes along who is so prolific that they almost redefine an industry single-handedly. German engineer Karl Benz (1844- 1929) was one such inventor. During the 1870s and 1880s he secured many patents—including the speed regulation system known as the accelerator or throttle in 1890—that represented  significant developments in the - technology of the automobile. Being one of the first to patent on many aspects of the design of the internal combustion engine eventually led Benz to become a leader in the field of automotive design. The throttle performs a simple function in the internal combustion engine. The fuel—usually gasoline—is mixed with air before being ignited in the cylinders to produce the small explosion that fires the piston, which in turn rotates the drive shaft turning the wheels. more...