Today, we tell about how people learned an important piece of information necessary for safely sailing on the oceans. It is called longitude

Navigators could find a ship's latitude, but not longitude, by observing the stars

On a foggy October night in seventeen-oh-seven, four English navy ships hit rocks in the Atlantic Ocean and sank.  Two thousand men drowned.  The ships had been sailing in the thick fog for twelve days.  There was no sure way to know where they were.  The commander of the ships had been worried that they could hit rocks if they were not careful.  He asked his navigators for their opinion on their location in the ocean

The navigators did not really know.  They told the commander they thought they were west of a small island near the coast of northwestern France

They were wrong.  Instead, they sailed onto rocks near a small group of islands southwest of England's Atlantic coast.  The navigators' lack of knowledge led to the loss of four ships and two thousand lives

When people began sailing out of sight of land, sailors did not know how to tell where they were on the open sea.  Land travelers can look at a mountain, or a river, or an object that shows them where they are in relation to where they came from.  On the ocean, however, there is no sign to tell a sailor where he is

The most important device for knowing directions on the ocean is a compass.  A compass is a device containing a metal object that points toward the magnetic north pole.  This shows navigators the direction of north, and therefore also south, east, and west.  But sailors need more information to sail safely on the open sea

Most maps of the world show lines that are not on the Earth's surface.  One line is the equator.  It is an imaginary line around the widest part of the Earth.  There are similar lines both north and south of the equator.  These circles become smaller and smaller toward the north pole and the south pole

These lines, or circles, are parallel - meaning that they are equally distant from each other at any point around the world.  These lines show what is called latitude

A navigator can know the latitude of his ship by observing the location of stars, where the sun rises in the morning and sets in the evening, and what time of year it is.  With this information he knows where his ship is in relation to the north or south pole and the equator

Still, there is one more important piece of information necessary for safely sailing the oceans.  For many centuries, scientists, astronomers and inventors searched for a way to tell longitude.  The lines of longitude go the other way from latitude lines.  They stretch from the North Pole to the South Pole, and back again in great circles of the same size. All of the lines of longitude meet at the top and bottom of the world

In her book, “Longitude,” writer Dava Sobel tells the story about longitude and how the problem of knowing it was solved

For centuries, the great scientists of the world struggled to develop a way to learn longitude.  To learn longitude at any place requires knowledge about time.  A navigator needs to know what time it is on his ship and also the time at another place of known longitude - at the very same moment

The Earth takes twenty-four hours to complete one full turn or revolution of three-hundred-sixty degrees. One hour marks one twenty-fourth of a turn, or fifteen degrees.  So each hour's time difference between the ship and the starting point marks a ship's progress of fifteen degrees of longitude to the east or west.  Those fifteen degrees of longitude mark a distance traveled

At the equator, where the Earth is widest, fifteen degrees stretches about one thousand six hundred kilometers.  North or south of that line, however, the distance value of each degree decreases.  One degree of longitude equals four minutes of time all around the world.  But in measuring distance, one degree shrinks from about one hundred nine kilometers at the equator to nothing at the north and south poles

For many centuries, navigators hoped they could find longitude by observing the movement of stars at night.  During the day, the sun provided information about the time on a ship, and its direction.  However, it did not provide necessary information about the time somewhere else.  In the sixteenth century, one astronomer suggested that navigators could observe the moon as it passed in front of different known stars to tell longitude.  But, there was not enough information about the stars to use this method effectively.  Astronomers could not tell exactly where the moon would be from one night or day to the next

Yet it seemed to those seeking to solve the longitude problem that the only solution was in the moon and stars

During the seventeenth century, English astronomers began a major effort to map the stars and their relationship to the moon as it passed across the sky.  Royal astronomer John Flamsteed worked at this task for forty years. The next royal astronomer, Edmund Halley, spent another forty years gathering information about the moon's orbit

After many years of gathering the necessary information, it became possible to learn longitude by observing the stars and the moon.  In seventeen sixty-six, Royal Astronomer Nevil Maskelyne published the Nautical Almanac and Astronomical Ephemeris

It contained all the necessary information about the moon and stars that sailors would need to help them learn their longitude

This new method was not simple.  A navigator had to use complex observing instruments to note the position of the moon and stars.  Then he had to seek the correct information in the Nautical Almanac about the moon and stars at that time of night or day.  The final step in the process was to take the mathematical information from the book, link it to the current information and solve the resulting problem.  This took an average of four hours to do

John Harrison

While scientists were studying the stars and moon to solve the longitude problem, a man named John Harrison was working on another project.  He was trying to build a clock that would help sailors learn longitude.  His task also was difficult and complex.  Mister Harrison had to develop a clock that was not affected by the movement of a ship on the ocean or changes in temperature or atmospheric pressure

He began developing his clock in seventeen thirty.  It took five years to complete.  The complex device weighed thirty-four kilograms.  Several years later, Mister Harrison built a second clock.  It was smaller, but weighed more than the first.  Mister Harrison was not satisfied and began working on yet another device

John Harrison's first clock

Twenty years later, he completed a device that was smaller than the first two, and weighed less.  But still Mister Harrison was not satisfied

Two years later, in seventeen fifty-seven, he produced a small clock that he could hold in his hand.  The clock could tell the correct time in two places, meeting the requirements for learning longitude on the sea

For many years after Mister Harrison's work was completed, the idea of using a clock to learn longitude was rejected. However, that opinion changed when manufacturers learned how to make better and less costly versions of Mister Harrison's clocks.  The clocks became known as chronometers

By eighteen  fifteen, five thousand chronometers were in use on ships sailing the world's oceans.  The complex documents and mathematical work were no longer necessary.  Almost any sailor could tell what his longitude was by simply looking at a clock.  The world had changed

John Harrison's clocks can be seen today at the Old Royal Observatory in Greenwich, England.  The first three are still operating, showing the correct time. To look at them is to see the simple solution to a problem that worried people for many centuries.  Today, the solution to the problem is so common that it is difficult to understand that there was a problem at all

  This week we look at an industry that is facing major changes -- the automobile industry

On the road, near Yosemite, California

Americans, possibly more than any other people, love their cars.  Ownership of cars is a sign of middle class wealth.  A car has long been part of the American dream.  For many people, nothing provides a feeling of freedom like driving in a powerful car on the open road.  But high fuel prices and changes in technology are causing people to change the way they look at the car

The car industry is changing more quickly than almost any other industry.  Just ask General Motors.  This year the American company celebrates one hundred years of being in business.  GM remains the biggest car company in the world for now.  But Toyota of Japan is positioning itself to become the world leader very soon.  General Motors has been losing market share to foreign carmakers at home for years.  For two thousand seven, General Motors lost almost thirty-nine billion dollars.  That is believed to be the largest one-year loss in the history of the auto industry

General Motors finds itself in a changing marketplace.  During the nineteen nineties, much of GM's profits came from the sale of large sports utility vehicles, or SUVs.  However, rising gas prices have made these big, fuel-hungry vehicles unpopular.  And GM has struggled to offer new vehicles that use less fuel

However, GM has made its own changes.  In January, Mark LaNeve, GM's North American vice president of sales and marketing, spoke at the Washington, D.C. Auto Show.  He discussed ways that GM was changing itself into a car company for the twenty-first century.  He said that GM is looking forward to competing in the next one hundred years.  Mister LaNeve noted that not only was it important for GM to compete in the United States but also around the world

The fastest growth markets are not in industrial nations any longer but in the developing world.  And in these areas, GM is doing increasingly well.  Mister LaNeve said that GM had increased sales in three of four areas around the world.  The North American market was the only one in which sales did not grow

The market for cars around the world is changing in ways that are more complex than simply the size or style of cars.  One of the most interesting new developments comes from India's biggest company, the Tata Group, which owns Tata Motors.  Tata Motors recently bought the high-cost car models Jaguar and Land Rover from American carmaker Ford in a deal worth two-point-three billion dollars

But in January, Tata Motors made big news by announcing that it would start selling a

Tata Motors' Nano

very small car that costs only two thousand five hundred dollars

The car, called the Nano, is designed mainly for India's home market, but its price has caught the attention of the world.  The Nano is the result of a different kind of engineering.  Instead of designing things to add to the vehicle, engineers thought of ways to remove things. For example, the car has very little storage space.  Parts like the steering column, which helps the car to turn, are made of less costly, lighter materials.  As with any lightweight car, safety is a major issue.  The car could be very dangerous if it is in an accident.   But the Nano does have four doors and five seats.  And its price puts it within the reach of millions of people in India

The 2008 Smart Fortwo

Tata Motors' Nano is mainly meant for the Indian market.  But the German company Daimler makes a very small car meant for markets in industrial countries.  It is called the Smart Fortwo.  Almost eight hundred thousand of an early version of the car have been sold in thirty-six countries.  Now Daimler will try to sell the Smart Fortwo in the American car market

The car is less than three meters long and less than two meters wide.  Still it has many of the things that people in industrial countries expect from a car.  For example, the car can have a radio, air-cooling and many other details.  However, its cost is not as low as you might think.  The least costly version of the Smart Fortwo is over eleven thousand dollars

Smaller cars are just one direction that the car industry is taking.  The industry is also producing cars that limit pollution and have a less harmful effect on the environment.  Many experimental versions of cars are being made using new technologies.  These include cars that run on fuels like ethanol, hybrid cars that use both fuel and electric power and fully electric cars.  Added to these are fuel cell vehicles

GM's Chevy Equinox Fuel Cell

At the Washington Auto show, a GM product called the Chevrolet Equinox Fuel Cell won top honors as an environmentally friendly vehicle. This fuel cell car won the Green Car Journal's Green Car vision award.  The Equinox Fuel Cell is powered by an engine that uses hydrogen to produce electricity

But recently, both GM and Toyota have questioned whether fuel cell cars can be offered at a price most people can afford.  GM Vice Chairman Bob Lutz spoke at the auto show in Geneva, Switzerland last month.  He said there has been recent progress in power-storing lithium-ion batteries.  He said future electric cars may be able to travel nearly five hundred kilometers before the batteries need to be recharged

Toyota is working on fuel cell cars too.  However, the company's president, Katsuaki Watanabe, confirmed that fuel cells are just too costly to be available in the next ten years.  Toyota is the leading maker of hybrid vehicles.  These run on both electrical power and gas

The automobile industry is changing in ways that would seem surprising to people only a few years ago.  Toyota, for example, is expected to become the largest car company in the world very soon.  But while Toyota has gained market share in North America and other Asian countries, the company is facing falling sales at home

In Japan, new car sales fell to a thirty-five year low in two thousand seven.  Sales for new cars, trucks and buses fell over seven percent.  High fuel costs and good public transportation are two reasons driving has become less popular in Japan

An opinion study by a Japanese newspaper found that only twenty-five percent of Japanese men in their twenties wanted a car at all.  That was down from forty-eight percent in two thousand.  The study was reported by the Wall Street Journal   

A Zipcar in New York City

Another trend involves not owning but sharing a car.  Zipcar is a company based in Cambridge, Massachusetts.  It is the world's largest car-sharing business.  Members pay each time they use a Zipcar.  The car is left in a place were it is available to other members

The company is growing quickly.  Zipcar recently joined with a similar company, Flexcar.  The merger is expected to be complete soon.  The combined company will have one hundred eighty thousand members and five thousand vehicles.  Zipcar does business in the United States, Canada and Britain

And Zipcar is not the only company interested in car- sharing.  Reports say vehicle rental businesses are interested in competing with Zipcar.  In early February, Enterprise Rent-A-Car entered the car-sharing business in Saint Louis, Missouri.  Its program is called WeCar.  Other companies such as U-Haul International have similar car-sharing businesses and the car rental company Hertz is considering one

Enterprise, which is the biggest car rental company by sales, says it is seeking a different business model from Zipcar.  It wants to provide shared cars to businesses

Shared cars are seen as an environmentally friendly way to use cars without owning one.  Car- sharing reduces the number of cars on the road.  Many of the cars are models that burn less fuel and produce less pollution.  For example, Enterprise provides the Toyota Prius hybrid car for its members

Car-sharing could be one way that people use cars in the future.  Smaller cars and electric models are also a growing part of the future of cars.  But as tens of millions of new cars are sold each year, one thing is clear: cars are still as popular as ever