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History Magazine cover
The 1650s
Victoria L. King examines a decade of civil unrest and enlightenment in Europe.

Birth of the Boardwalk: A Sandy History
Russell Roberts looks at the illustrious beginning of the "walk of boards".

David A. Norris looks at the plastic of the Victorian Age.

The Battle of Cannae
Nicky Nielsen tells the story of the ancient battle between Hannibal Barcas and his sworn enemy, Rome..

Barter and Trade in Colonial America
Joanne Liu looks at the early history of Colonial America where currency as we know it was scarce.

Chroniclers & Scribes — Medieval Historical Writers
William Stroock chronicles some of the great medieval documents that have survived.

The Pedigree of Platinum
Steve Voynick relates the fascinating history of the "other" precious metal.

Pyramids and the Occult — Fact or Fiction?
Pamela D. Toller chronicles the search for the magical meaningn of the pyramids.

The Early Days of Radio
From the book With Amusement For All: A History Of American Popular Culture Since 1930, author LeRoy Ashby looks at the early programs that made radio so popular.

"The Storm": Killer Hurricane Devastates Galveston, Texas
Joanna Bostwick Backman tells the story of a killer hurricane.

Fire Below! The Devastating Reality of Coal Bunker Fires
Patrick McSherry chronicles the dirty and dangerous history of coal bunker fires and the men that fought them.

The Timeless Appeal of Clocks
Phill Jones chronicles the history of timekeeping and its impact on history.

Lizzie Borden and the Fall River Axe Murders
Daniel M. Hoenig describes the enduring interest in this case of murder most foul.

Navigation Before Netscape

Edwin M. Knights charts the history of early navigation.

Though the Chinese had much earlier success with navigational aids, European explorers were soon well armed with an impressive array of instruments.

SOMETIMES IT'S BETTER to be a bobolink. Or a pigeon. Or even a tuna. These are but a few of the creatures that have directional abilities that humans only wish they had. Put us in a dense fog and we go in circles.

Early sailors were very much aware of their limitations, hugging the shorelines, looking for familiar landmarks, and going ashore at night. As they began to venture out to sea, they learned to recognize other signs of nearby land, such as certain types of birds and fish, seaweed and other drifting objects that had been washed out to sea. They could also take soundings of water depths, keep track of time and measure their speed. The better navigators became expert in estimating a ship's position by observing the sun, moon, stars and planets. The poorer navigators just disappeared.

The astrolabe was another essential tool in celestial navigation.

Celestial Navigation

The art of studying the sky to guide ships across the ocean is called celestial navigation. The stars and other celestial bodies are so far away they seem to be located on the surface of an imaginary sphere, with its center located at the center of the earth. The Phoenicians and Greeks were among the first to attempt sailing at night. They didn't realize it, but landlocked nomads were already using the stars to find their way at night across the desert sands on their ships of the desert, camels. Archeological findings show that the Vikings and Polynesians also made some long, remarkable voyages.

Navigators found they could determine a ship's latitude quite easily by checking the height of the noon sun. The Greeks also invented the cross-staff and the astrolabe, used to measure the altitudes of celestial bodies. The cross-staff was a stick about a yard long, with a shorter sliding stick set at right angles. The navigator pointed the staff at a spot halfway between the horizon and the sun or a star. The crosspiece was then adjusted until the sights at its ends were in line with the celestial body and the horizon. A scale along the stick showed the angle of the body above the horizon.

The astrolabe was usually made of bronze, with a pointer pivoting from its center. One sailor held the astrolabe by means of a small ring at its top, while another knelt facing the instrument's rim. The kneeling person aimed the pointer at the star and read the angle from markings on the disk.

Many factors caused a ship to drift from its intended course. Among these were the wind, waves, swells and ocean currents. Clearly there was a need for a better way of staying the course!

The Magical Lodestones

Just when the Chinese found the first lodestone depends upon which reference you want to believe, but it was well over 2,000 years ago. These interesting rocks were referred to as "tzhu shih", or loving stones, as they liked to kiss. In the sixth century bc, a Greek writer noted that pieces of iron were attracted to certain rocks. This phenomenon, which we now know as magnetism, intrigued the Chinese greatly. They found that if they floated a piece of lodestone on a small piece of wood, it always aligned itself in a north-south direction. They developed the first compass, which was a spoon-shaped lodestone resting on a bronze plate. The handle of the stone always pointed south. They also pierced a couple of short sticks with a coarse iron needle that had been magnetized by rubbing on a lodestone and they found it also always pointed north-south.

The Chinese used the magnetic compass to orient buildings, tombs and even furniture to positions they felt would harmonize with nature and they found many other applications for the compass, including medical treatment. There is evidence that Chinese sailors were using magnetic compasses as early as the sixth century bc. Europeans didn't use them until almost 1,200 years later.

The cross-staff was used to measure the altitude of celestial bodies relative to the horizon.

What's a Lodestone?

The lodestone got its name from the north star, Polaris, which was the seamen's lodestar, showing them the way. It consists of magnetite, a massive oxide of iron ore. Not every piece of magnetite can become a lodestone; it requires a certain crystalline structure. And something else must occur to give the stone its magnetic personality. This happens when the stone is struck by lightning. The huge electrical discharge, lasting but a split second, has been shown to transform the right types of magnetite into lodestones.

Lodestones weren't practical to use as compasses, but the Chinese had already found they could transfer magnetism to an iron needle and float this in a small container. Europeans kept improving the magnetic compass, but they didn't know why it pointed north. Most scientists felt it was attracted to the pole star. In 1269, an Italian scholar from Picardy named Peregrinus wrote a paper stating a magnet had two poles, north and south. He noted that similar poles repelled and opposite poles attracted each other. A Buddhist astronomer reported that a compass didn't point directly at the north as early as 720ad, but Europeans didn't find this out until long after Columbus made his epic voyages.

Chris Flunks Celestial Navigation

Columbus, who was from Genoa, sailed by dead reckoning, as did most everyone else in the Mediterranean. Since most of the sailing was east or west at about the same latitude, there wasn't much incentive to practice celestial navigation. He did try it a few times, with rather poor results. Determining longitude requires a very accurate timepiece; at the equator, every error of one second means an error in longitude of about 1/4 mile. Thus Columbus' ampoletta, or sand glass, was of no use. It had to be corrected every midnight (if it were clear) using a little instrument appropriately called a nocturnal, which worked by measuring the rotation of the stars around Polaris. It wasn't until 1728 that John Harrison came up with a chronometer that would keep accurate time at sea.

Many years later it was determined that the magnetic compass really pointed to a spot in Hudson Bay about 11.5 degrees from true north. This compass error, sometimes called the declination, was methodically recorded on maps in which isogonic lines show the boundaries of the differences in variation from true north.

Making the Compass Work at Sea

Using a compass aboard a ship, especially a sailing ship, required a special mounting to compensate for the pitching, rolling and yawing of the vessel. This was achieved by designing a housing known as a binnacle, which would maintain the compass relatively level with the horizon. Early models of the compass didn't retain their magnetism very well, so each ship had to carry its own lodestone to "recharge" the compass needle. The needle's shape was changed to a parallelogram; later several parallel magnets were mounted to a compass card pivoting around a jeweled bearing and surrounded by fluid.

Improving the compass did not necessarily increase its reliability, however, because as more and more iron was used in ship construction, more errors were introduced in compass readings.

And still nobody understood why this area close to the North Pole attracted a magnet. Did the earth have a lodestone in its core? Then it was found that the direction of the magnetic field was slowly changing, followed by more confusion resulting from the finding that iron loses its magnetism when heated to 1,000 degrees. Since the interior of the earth is very hot, how could it contain permanently magnetized iron?

Why is the Earth Magnetized?

One theory is that the core consists largely of molten iron and that convection caused by the heat from the core causes liquid iron to move in a rotational pattern. Sir Joseph Larmor proposed that the Earth was a dynamo in 1919. In the middle of the 20th century geologists made a remarkable finding - some ancient rocks showed the earth's magnetic field had pointed in the opposite direction. It seems likely the polarity of the earth has shifted around several times. There are predictions that the magnetic polarity of the earth may reverse again in 1,500 to 2,000 years. This is going to upset a lot of birds, fish and bumblebees, if they are still around. Findings that the magnetic fields of some other planets are not aligned similarly with rotation also bring into question the dynamo theory.

The standard compass became less practical with the increased popularity of steel-made ships, as the steel threw off the compass' ability to find magnetic north. The gyroscope, developed in the ealry 1800s, allowed for development of a compass that overcame this problem.

The Gyrocompass

The first gyroscope is credited to J.G.F. Bohnenberger in 1817, and J.B.L. Foucault, a French physicist, explained its inertial principles in 1851. The harnessing of electricity enabled G.M. Hopkins to develop the first electrically driven gyroscope in 1890. By now most ships were being made of steel, creating major difficulties for a magnetic compass. This was of particular concern in naval warfare, and two great naval powers, Germany and the US, hastened to develop military applications for the novel gyroscope.

A gyroscope will always point in a single direction in space. If force is applied, it reacts to it at right angles. Dr. Hermann Anschutz of Germany patented the first north-seeking gyrocompass in 1908. The same year, Elmer Sperry, an American, developed the first ballistic gyrocompass. The gyrocompass, aligned in a north-south axis, maintains this direction no matter what course is followed by a ship or plane. It is unaffected by metal and now navigators had an instrument that would point to true north. One master compass can control several "repeater" compasses or provide information to an automatic pilot or helmsman. Sperry went on to perfect the gun battery controls and gyro stabilizer systems for ships during WWI. His company produced "Metal Mike," the first gyro pilot system for ship's steering and later developed numerous variants and electronic amplification. Using Sperry's artificial horizon and the aircraft directional gyro made possible the first recorded all blind flight in 1929. Elmer Sperry had amassed 360 patents by the time of his death in 1930.

Leading the Way

When HMS Resolution sailed forth in 1772 to test the current states of the art in navigation, including chronometers, the constellations and planets in the skies above still bore, as they do today, the ancient names bestowed upon them by celestial navigators centuries ago. Today's traveler has high-tech navigational aids, but the Boeing 747 still carries a magnetic compass on its instrument panel, corrected for the magnetic effects of surrounding electronic equipment. The magnetic compass deserves a place of honor in any Instrumentation Hall of Fame. And the wondrous gyrocompass, conceived almost a century ago, filled the need to find true north for those high in the sky or far beneath the surface of the sea. Meanwhile, fish and mammals, birds, bees and even bacteria just take off and head in the right direction. While some birds definitely use stellar constellations during their migrations, other organisms may have single-molecular magnets of manganese or iron that act as built-in compasses. Perhaps humanity had them, too, until the magnetic polarity of the earth reversed.

Perhaps that is why we walk in circles in the fog.

This article originally appeared in our October/November 2001 issue.