Lightning in a Bottle

Imagine this.  As the last of the experiments comes to an end, Franklin begins collecting the scattered scraps of paper on the workbench.  “So,” he says, “what have we learned together?”

“Electricity can make sparks,” Dustin says.

“Sure,” Franklin nods.

“It can also pull things,” you add, “and also push things away.”

“I agree,” Franklin says.

“You still haven’t told us how you stored lightning in a bottle,” Dustin says.  “Like I said before, I think it is impossible and very dangerous.  So I am just not sure you ever did it.”

“Ah, yes,” Franklin says.  “I will show you how I stored lightning in a bottle.”  Franklin walks to the back of the little bright room.  There you see a row of glass jars sitting on a table.  Metal rods rise from the tops of the jars and connect them together.  Franklin places his hand on one of the jars.  “These are called Leyden jars,” he says.  “I made these myself.”

“Are those the bottles you put lightning into?” you ask.

Franklin grins.  “Yes they are.”

“How did you do it?”

“That painting by the door—do you remember it?”  Franklin asks, pointing to the painting that had caught your attention when you first entered the room.  The kite, the key, the storm—it all comes back to you.  

“That was a remarkable day,” Franklin continues.  “I had been thinking about lightning for years.  Many people thought lightning was something entirely different from the sparks we were making a moment ago.  But I suspected they were the same thing.”

“You think they are the same thing?” Dustin interrupts.

“Well, that is what I was thinking,” Franklin says.  “The difficulty was proving it.”

“You can’t prove it,” Dustin says confidently.

“Why not?” Franklin asks, surprised by Dustin’s audacity.

“Obviously they are different,” Dustin says, as though speaking to a young child.  “What we were doing earlier was just picking up scraps of paper and giving each other little zaps.  Lightning can kill you!  That is why you shouldn’t fly kites in storms, and why you shouldn’t try to catch lightning in a bottle!”

Franklin turns to you, chuckling.  “As you can see, I had a difficult time proving my point.  But I was determined to do so.  So one afternoon, a thunderstorm began building over Philadelphia.  Dark clouds rolled across the sky, and distant thunder could already be heard.  Most sensible people were hurrying indoors.  But not me.  I ran toward the storm, with my son William following closely behind.”

“You took your son out there?!” Dustin nearly shouts.  “This is crazy!”

Franklin doesn’t seem to notice.  He continues with his story.  “I had built a kite specifically for such an occasion.  It was not an ordinary child’s kite.”  Walking over to the painting, he places his finger on the kite.  “I made the kite from a silk handkerchief stretched over a wooden frame.  Silk was important because it could withstand the rain better than paper.”  Pointing to the top of the kite, he adds, “I attached a sharp metal wire here at the top of the kite.”  Then running his finger along the kite’s string, he stops at the key hanging from the string, and says, “I used hemp for this part of the string, and I tied a metal key here at the end.”  

You follow along, looking at each part of the kite as he explains.

“Of course, I wasn’t holding the hemp string,” Franklin continues.  “Below the key, I attached a short length of silk ribbon, and that is what I was holding.”

Franklin then turns to Dustin.  

“That detail mattered, my young friend,” he says.  “I knew the rain would soak the hemp string, and that electricity could then flow through the string, giving me quite a shock, as you say.”  

“The ribbon wouldn’t do the same?” you ask.

“No, the silk ribbon would remain dry,” Franklin says.  “That allowed me to hold the kite safely.”  

Dustin crosses his arms.  “I don’t get it,” he says.  “Still seems crazy to me.”

Franklin continues with his story.  “When the storm drew near, William and I launched the kite into the air, and then took shelter in a little barn nearby.  The kite danced and pulled against the wind, but nothing happened at first.  Then I noticed something strange: the loose fibers sticking out from the hemp string began to stand straight up, like tiny hairs standing on end.”

“Kind of like the pieces of paper that we moved with the electricity,” you note.

“Yes, exactly,” Franklin says.  “That caught my attention.  Something was happening.  The storm clouds above were filling the kite and the wet string with electrical charge.  The charge was traveling down the hemp string.  The key was tied to the hemp string, you remember.  So I moved my knuckle near the key.  Do you know what happened?”

You shake your head.

“Zap!” Franklin exclaims.  “I got shocked!  Just like you did earlier when we were making lightning.”

“Did you get hurt?” you ask.

“No, it was just a tiny spark.  It leaped from the key to my finger.  It didn’t hurt.”

“If it was just a tiny spark,” Dustin says, “then what did that prove?”

“That little spark told me everything,” Franklin responds.  “It was exactly the same sort of spark I had seen countless times in electrical experiments.  At that moment I knew I had been right.  The lightning in the sky and the electricity in my laboratory were the same thing.”

“You still haven’t told us how you stored lightning in a bottle,” Dustin interrupts, seemingly unimpressed by Franklin’s story.

“That is coming, my young friend,” Franklin says.  “As I was saying, it became clear that the hemp string was carrying electricity from the storm down to the key, and sparks were jumping off the key.  So that is when I took one of these Leyden jars I showed you, and placed the top of the jar near the key.  Sure enough, sparks began jumping from the key to the jar.  It was fantastic!  Just imagine my excitement!  There I stood in a soggy field, blown about by a thunderstorm, with electricity coming down from the clouds and flowing into my bottle.  Amazing!”

“So what did you do?” you ask.

“Well, I returned home and told everyone that I stored lightning in a bottle.”

“That seems like an exaggeration,” you say, a bit skeptically.

“Sure, the great lightning bolts remained in the clouds overhead,” Franklin admits, “but it is true that the same electrical charge that was in those clouds—the same charge that makes lightning—that charge was now in my jar.”

“You have more than one jar there,” you note.

“Yes, I have collected several,” Franklin nods.  “They look like a group of cannons when they are all together, don’t you think?”

“I guess so,” Dustin says, perking up at the mention of cannons.

“That’s what I thought, so I started calling this a battery,” Franklin says.

“That’s what ‘battery’ means?” you ask.  “A group of cannons?”

“Yes,” Franklin says, “or in this case, a group of jars storing electricity.  Once I found that one jar can store electricity, I wanted to see if many jars could be hooked together to store even more electricity.  So I joined them into a group.  And guess what?  It worked!”  Franklin pats the group of bottles on his table.

“Those jars really can hold electricity?” Dustin asks.

“They can,” Franklin says.

“How?”

“An excellent question,” Franklin responds.  “I will show you how.”

Franklin crouches, pulls two empty buckets from underneath the workbench, and places them on the floor in front of you.

Dustin looks at the buckets, and then back at Franklin.  “I thought we were talking about electricity,” he says.

“We are,” Franklin assures him, “but sometimes a good picture helps us understand something we cannot see.”

Franklin picks up a pitcher and fills one of the buckets with water, leaving the other empty.

“Suppose these buckets are connected by a pipe,” he says.  “What do you think will happen?”

You offer an answer: “The water will flow into the empty bucket.”

“Why?”

“Because one bucket has more water,” you say.  “The water will travel through the pipe from one bucket to the other.”

Franklin nods.  “When will the water stop flowing from one bucket to the other?”

“When both buckets have about the same amount,” you say.

“Right,” Franklin says.  “Water seeks balance.  It tries to level itself out.”  He sets down the pitcher.

“I still don’t see why we are talking about water,” Dustin says.

“Electricity behaves in a similar way to the water,” Franklin responds.  

“That seems unlikely,” Dustin says.

“It is not a perfect comparison,” Franklin admits, “but it is a useful one.”

Franklin points to one of the Leyden jars.  “When I carried this Leyden jar into the field that one evening, it was like the empty bucket.  And the key was like the full bucket—it had been filled with electricity from the clouds, just as I have filled this bucket from my pitcher.  So when I brought the Leyden jar close to the key, the electricity flowed from the key to the bucket.  Electricity was seeking balance, trying to level itself out.  Do you see that?”

You nod slowly.  “So when a charged object comes near the empty jar, the electricity flows into the jar until both are evenly charged?”

“Yes.  Just as water flows from a full bucket into an empty one.”

You think for a moment.  “When you put your finger near the jar, you saw a spark jump from the jar to your finger.  Why did that happen?”

Franklin smiles.  “Yes, good thinking.  That spark jumped out of the jar for the same reason.  The jar was full of electricity, like the full bucket here, and I was like the empty bucket.  The electricity flowed from the jar to me, flowed to the place with less charge to even everything out.”

“And that’s the zap?” Dustin asks.

“That’s the zap.”

You glance over at the scraps of paper you had used earlier.  “Then what about the paper scraps and the dancing snake?  Why were those pulled off the table by electricity?  Water doesn’t do that.  It doesn’t pull things toward itself.”

“No, it doesn’t,” Franklin agrees.  “That is one place where the comparison seems to break down.  Electricity is stranger than water.  Not only does it flow toward balance, but it can also pull things toward itself as it seeks that balance.”

“So you think the pulling and the flowing are connected?” you ask.

“I believe they are.”

Suddenly turning to Dustin, Franklin grins, and says, “You see, my young friend, I have captured lightning in a jar.  I captured lightning, brought it back, and released it when I wanted.”  Then looking at the collection of Leyden jars for a moment, Franklin gets a faraway look, and quietly says, “That may not sound like much now, but I cannot help thinking that this battery holds the promise of amazing power.”