The Last Days of Night(18)

“Do you know what this all means?” asked Paul of Westinghouse. Paul turned and saw that his client’s mouth was literally agape. “Sir?”

“I’m not sure anyone does,” replied Westinghouse, entranced by the display of mathematical acumen at the front of the hall. “Is he multiplying ‘K’ by the cosine of—what is that? A ‘U’?”

“Afraid you’re asking the one man here who doesn’t know what a cosine is.”

At the front of the room, Tesla scribbled on, giving what appeared to be a very animated lecture into the chalkboard as he did so.

“Look,” said Paul, “can you give me the big picture here? What are those machines? Generally speaking.”

“For God’s sake—that one is a generator. Over there is a motor. And the middle is a stepping-down transformer, looks like.”

“Why such a fuss, then?” Paul was relatively certain he’d heard of all these things before.

“It’s the current,” said Westinghouse. “He’s made—well, he’s saying he’s made, I can’t tell right now—a closed system of currents in alternation.”

Westinghouse furiously scribbled in his notebook. Around the lecture hall, dozens of other engineers were engaged in similar conversations, trying to make sense of the demonstration.

“What’s alternating current?” inquired Paul.

“There is a part of me that almost feels some measure of satisfaction at your finally asking me for a scientific education. But most of me just wants you to hush.”

Westinghouse tore the top page from his notebook and began to sketch a simple diagram. “There are essentially two varieties of electrical current. Continuous, sometimes called direct, which has been the standard in use since Faraday. And alternating, which is actually just as old but isn’t to be found anywhere outside of a laboratory. Because it’s useless.”

“Useless?”

“Do you know how electricity is generated?”

“Yes!” answered Paul enthusiastically. “A generator.”

“Dear God…I mean do you know how a generator works? How it generates current?”

“Oh…No.”

Westinghouse gestured to his diagram as he explained the components he’d sketched. “Simply, and do understand that I’m excising a number of salient details in the name of brevity, there is a magnet, and then a coil of wire rotating around that magnet. One moves the coil with a hand crank, typically, or a steam engine in bigger systems, and as the coil moves through the magnetic field, current is generated. Got it?”

“I suppose. But why? Why does spinning a wire coil through a magnetic field create electrical current?”

“Nobody knows.”

“What do you mean ‘nobody knows’?”

“I mean that no one knows. Electrical energy is a force. It just happens. Only God himself knows where it comes from. For us mere mortals, and for us particularly bright mortals who call ourselves scientists, all we know is how to make the stuff. Would you like me to continue?”

“Very much.” While Paul hoped that Westinghouse would not get impenetrably technical, any explanation he provided would still be more comprehensible than the buckshot of white chalk lines Tesla continued to spread across the blackboard.

“Every time the coil passes around the magnet, it creates a burst of electricity. Zoop! Zoop! Like rifle fire with every spin. Though please note: It’s actually nothing like rifle fire; I’m employing a metaphor so you’ll understand. Now, in order to properly power a device, these bursts are fed into something called a commutator. The commutator smooths these bursts of energy out into an even stream. Like a dam in a river.”

“That makes sense.”

“I’m thrilled to hear it. Because now it gets more complicated. All electric systems must be closed loops, correct? Part and parcel of the strange force. Electricity will only flow in a complete circuit; a partial one will not do. So a generator, as I said, summons the energy from God knows where and then sends it to a commutator for smoothing out—think of turning a series of distinct water droplets into a gentle flow. The commutator then sends this flow to whatever device it’s powering, let’s say a motor, or a lamp. Then, to complete the loop, the lamp is connected back to the commutator, then back to the generator.”

Westinghouse showed Paul his hastily sketched diagram. It depicted a circle, with a box marked “generator” on one side, a box marked “commutator” connecting in the middle, and a box marked “motor” on the far side. Westinghouse moved his finger clockwise around the circle to indicate the path of the electricity. “The current flows continuously, constantly, directly around this loop. Like a circular river. Clear enough? D/C, we call it.”

“I’m following,” said Paul with moderate confidence.

Westinghouse gave a short humph, seemingly unconvinced. “There’s another way to build this circuit. It’s the same circuit, only a different type of generator. Remove the commutator. Now, instead of sending current around constantly like before, it’s sending it in bursts, yes? Bap! Bap! Bap! And due to an oddity of generator design that’s too subtle for you to understand, instead of sending current around the circle only clockwise”—Westinghouse traced his fingers around the circle to further elucidate his point—“these bursts of current switch directions. A burst goes clockwise, then stops, then reverses itself and goes around counterclockwise. Then stops, reverses again, et cetera. It makes these reversals hundreds of times every second. The current ‘alternates,’ you see. A/C. And I hope you realize that when I say clockwise and counterclockwise, I’m again speaking in metaphor, since electricity is not strictly speaking directional. You appreciate the use of metaphor?”