Lightning has terrified people since our ancestors first ran for the nearest safe cave. Many interpreted it as a sign of the gods’ displeasure. The ancient Greeks thought that Zeus fired lightning bolts down from Mt. Olympus when he was angry. In Europe, people interpreted thunderstorms as a sign from God. They were not considered a natural occurrence—they were supernatural.
Most people thought lightning was a kind of fire in the sky. No one had made the connection between electricity and lightning.
As a result, they had no way to defend themselves from lightning strikes. Many people thought that ringing church bells during bad weather would help protect them. When blessed by a priest or minister, bells supposedly had the power to vanquish storms and chase away demons. In reality, bell ringing often seemed to have exactly the opposite effect. In fact, even as the clanging bells sounded across the countryside, lightning sometimes zapped the bell towers and killed the poor ringers.
Why?
The answer, Franklin thought, was simple: lightning and electricity were actually the same thing. In a letter to Collinson, Franklin listed the similarities between them:
1. Giving light.
2. Color of the light.
3. Crooked directions.
4. Swift motion.
5. Conducted by metals.
6. Crack or noise in exploding.
7. Subsisting in water or ice.
8. Rending bodies as it passes through.
9. Destroying animals.
10. Melting metals.
11. Firing inflammable substances.
12. Sulphurous smell.
If lightning was electrical, Franklin reasoned, then ringing church bells was absolutely the worst thing to do during a storm. After all, bells are made of metal, and metal conducts electricity. Also, as Franklin had demonstrated, electricity was attracted by tall, pointy objects—high trees, lofty towers, the masts of ships, and church steeples. A church steeple was not the safest, but the most dangerous place to be near during a lightning strike!
There was only one way to find out if Franklin was right. “Let the experiment be made!” he declared.
In Experiments and Other Observations on Electricity, Ben described a test he thought would work. This was his plan: Raise an iron rod with a sharp point on top of a high tower or steeple. Fasten the bottom of the rod to a kind of “sentry box” where a man could stand, sheltered from the rain. Then, when lightning flashed across the sky, he could touch the rod with his knuckle or with a wire attached to a wax handle. If he drew sparks, then he would know that the rod was electrified—and that lightning is electricity!
King Louis V of France read about the experiment and was inspired. Why not carry out Monsieur Franklin’s ideas in France? At the king’s direction, scientists erected a sentry box with a 40-foot iron rod. On May 10, 1752, a soldier stood in it during a thunderstorm. Lightning cracked across the sky—and sparks shot out of the iron rod! The experiment worked!
In that instant, Benjamin Franklin became world-famous. He had proved that lightning and electricity were one and the same. But he didn’t learn right away that his theory had been correct. It took months for word of the French experiments to make its way across the Atlantic.
In the meantime, Franklin came up with another way to prove his theory. Philadelphia contained no buildings tall enough to build a sentry box. What else could he use to carry a metal point into the clouds?
What flew into the sky? Birds, balloons—and kites! That was it! He could use a kite!
Excitedly, Franklin gathered the materials he would need to make his kite. First, a large silk handkerchief. Since silk is stronger than paper, he figured, a silk kite would not rip in the wind.
Next Ben found two cross-sticks to support the silk. He tied each corner of the handkerchief to the ends of the sticks. Then he attached a thin, pointed wire to the upright stick. The wire would extend about a foot above the kite. To the other end of the stick, he attached a long string.
What would keep the electricity from flowing from the metal point down into his hand? Silk, which does not conduct electricity. So at the end of the string, Ben tied a silk ribbon. Finally, between the silk and the string, he tied a metal key. His kite was ready.
Franklin told only his twenty-one-year-old son William what he intended to do. That way, if he was unsuccessful, no one else would ever know.
Restlessly he waited for a thunderstorm. One hot June day, the sky grew black and the wind came up. Franklin and William hurried out to an open field. Franklin stood in the open doorway of a shed, holding tight to the end of the silk ribbon. William ran out into the middle of the field and launched the kite.
Up, up it went, swirling in the gusty wind.
Crack! Lightning flashed across the field. Boom! A thunderclap split the sky. Franklin put his knuckle to the key. Would he feel a spark?
Nothing. He tried hard not to be disappointed. How could he have been wrong?
Still he waited, the minutes ticking by. He felt the first cooling drops of rain begin to fall. He glanced at the rope.
What was happening? One by one, the loose threads of the string were standing straight up.
Cautiously he brought his knuckle towards the key. Closer and closer it came …
Zap! A spark shot out into the air.
He’d done it! He’d drawn electricity out of the sky!
Now the rain came pouring down. As Franklin held onto the string, William charged jar after jar with electricity. Franklin would test later to see whether this electricity gathered from the clouds had the same properties as the electricity gathered from the whirling glass globes.
By now the string was soaking wet. The wetter it got, the more easily electricity flowed, and the more William and Ben collected in the Leyden jars. But Franklin knew it was important to keep the silk ribbon dry. If the ribbon got wet, electricity would flow straight down the string into his hand and he would receive another huge electric shock. And that shock he might not survive.
Luckily, nothing terrible happened. Ben and his son made it home with all the charged jars. And news of Franklin’s achievement soon blazed across America and Europe.
Scientists everywhere tried to copy Franklin’s sentry box and kite experiments. In Russia, one poor scientist died when he failed to protect himself properly. A massive bolt flashed right through his body, electrocuting him.
Now Franklin had to figure out a way to make his discovery useful. He came up with a wonderful idea.
He would invent a way to protect buildings from lightning!
Franklin proposed that long metal rods be attached to the highest parts of buildings and down their sides into the ground. Then, when clouds became electrified during a storm, the electricity would be drawn out of the air and down the wire and be “grounded” into the earth. The building would be saved.
Franklin had invented the lightning rod! That summer, he put a lightning rod on his own house and on the State House in Philadelphia. This way the books of the Library Company would be safe during storms.
Slowly but surely, lightning rods were placed on buildings across Europe and America. Thousands of buildings were saved from destruction. The bell tower at St. Mark’s in Venice, for instance, was blasted by lightning eight times between 1388 and 1761. After being fitted with a lightning rod, it was never damaged by lightning again!
Once again, Franklin refused to patent his invention. He wanted all humanity to benefit from it. In Poor Richard’s Almanack for 1753, he published directions for constructing a lightning rod. If people installed the rods, he wrote, they would be safe from “the most sudden and terrible mischief.”
The world was grateful. And the awards began to pile up. Franklin received the prestigious gold Copley Medal from London’s Royal Society for scientific achievement. The King of France sent him his personal “compliments.” In America, Harvard and Yale Universities both awarded him honorary degrees. Years later, so did Oxford University in England and the University of St. Andrews in Scotland. From then on, the scholars of St. Andrews said, Benjamin Franklin should be called “the worthy Doctor.” So to the end of his life, Franklin—who had never gone to college—was known as “Dr. Franklin.”