• Choose a category
• All
• Classic-Fiction

Using thicker wire is a good solution, but that can be expensive. Ten-gauge wire (which Radio Shack sells as Automotive Hookup Wire at $11.99 for 35 feet, and you'd need twice as much because it has only one conductor rather than two) is about 0.1 inch thick but has a resistance of only 1 ohm per 1000 feet, or 5 ohms per mile.

Another solution is to increase the voltage and use lightbulbs with a much higher resistance. For example, a 100-watt lightbulb that lights a room in your house is designed to be used with 120 volts and has a resistance of about 144 ohms. The resistance of the wires will then affect the overall circuitry much less.

These are problems faced 150 years ago by the people who strung up the first telegraph systems across America and Europe. Regardless of the thickness of the wires and the high levels of voltage, telegraph wires simply couldn't be continued indefinitely. At most, the limit for a working system according to this scheme was a couple hundred miles. That's nowhere close to spanning the thousands of miles between New York and California.

The solution to this problem—not for flashlights but for the clicking and clacking telegraphs of yesteryear—turns out to be a simple and humble device, but one from which entire computers can be built.

Chapter 6. Telegraphs and Relays

Samuel Finley Breese Morse was born in 1791 in Charleston, Massachusetts, the town where the Battle of Bunker Hill was fought and which is now the northeast part of Boston. In the year of Morse's birth, the United States Constitution had been ratified just two years before and George Washington was serving his first term as president. Catherine the Great ruled Russia. Louis XVI and Marie Antoinette would lose their heads two years later in the French Revolution. And in 1791, Mozart completed The Magic Flute, his last opera, and died later that year at the age of 35.

Morse was educated at Yale and studied art in London. He became a successful portrait artist. His painting General Lafayette (1825) hangs in New York's City Hall. In 1836, he ran for mayor of New York City on an independent ticket and received 5.7 percent of the vote. He was also an early photography buff. Morse learned how to make daguerreotype photographs from Louis Daguerre himself and made some of the first daguerreotypes in America. In 1840, he taught the process to the 17-year-old Mathew Brady, who with his colleagues would be responsible for creating the most memorable photographs of the Civil War, Abraham Lincoln, and Samuel Morse himself.

But these are just footnotes to an eclectic career. Samuel F. B. Morse is best known these days for his invention of the telegraph and the code that bears his name.

The instantaneous worldwide communication we've become accustomed to is a relatively recent development. In the early 1800s, you could communicate instantly and you could communicate over long distances, but you couldn't do both at the same time. Instantaneous communication was limited to as far as your voice could carry (no amplification available) or as far as the eye could see (aided perhaps by a telescope). Communication over longer distances by letter took time and involved horses, trains, or ships.

For decades prior to Morse's invention, many attempts were made to speed long-distance communication. Technically simple methods employed a relay system of men standing on hills waving flags in semaphore codes. Technically more complex solutions used large structures with movable arms that did basically the same thing as men waving flags.

The idea of the telegraph (literally meaning "far writing") was certainly in the air in the early 1800s, and other inventors had taken a stab at it before Samuel Morse began experimenting in 1832. In principle, the idea behind an electrical telegraph was simple: You do something at one end of a wire that causes something to happen at the other end of the wire. This is exactly what we did in the last chapter when we made a long-distance flashlight. However,