In the 1890s two ways of moving electricity around a country were fighting each other, and only one of them could run a factory two hundred miles from a river. This is the short life of the man who built the winning one. It is a Who Was? biography, which means about a hundred pages, black and white drawings, a life told straight through from childhood to death, and sidebars along the way.
Tesla arrives in New York in 1884 carrying a letter of introduction to Thomas Edison. He works for him briefly, quits, digs ditches for a while, sells his motor patents to George Westinghouse, and helps win the argument about how America would be wired. By the last chapter he is dead in a hotel room, broke, feeding pigeons.
The science it actually teaches
There is a problem with this book and it belongs before the good part. The science in it is thin. You get the rivalry, the personality, the pigeons and the counting rituals, and you get told that alternating current won. You are not told what alternating current is, or why it won. So what follows is what your child should come away knowing, and some of it you will have to hand them yourself.
Direct current runs one way down a wire and keeps running that way. Alternating current reverses direction many times a second. That sounds like a fussy difference and it decides everything, because of one device. A transformer only works on current that is changing. Feed it alternating current and it hands you the same power back at a much higher voltage, or a much lower one, with no moving parts at all.
Why that matters: the power lost as heat in a long wire climbs with the square of the current running through it. Double the current and you quadruple the waste. So push the same power out at high voltage, keep the current small, and the loss nearly vanishes. That is why the wires on the poles outside carry thousands of volts and the socket in your kitchen carries a hundred and twenty. Something stepped it down on the way. Edison's direct current could not be stepped up or down, which is why his system needed a generating station every few streets. Tesla's could cross a state.
Alternating current is useless if nothing will run on it, and here is Tesla's real invention, the one the book skates past. Feed several coils with currents that peak at different moments and the magnetic field inside the motor does not simply flip back and forth. It sweeps around in a circle. Put a metal rotor inside a rotating magnetic field and the field drags the rotor along with it. No brushes, no sliding contacts, nothing rubbing, nothing sparking. That is what the word polyphase means, and there is very likely one of those motors running in your refrigerator right now.
The Tesla coil, the thing throwing sparks in every science museum, is a pair of coils tuned to the same frequency with air between them. Energy handed back and forth between two circuits that agree on a frequency piles up, and enormous voltage at very high frequency comes off the top. Tuning two circuits to each other is not a party trick. It is how a radio picks one station out of the air.
He also steered a boat around a tank by radio in front of a crowd in New York, at a time when most of that crowd assumed a small man was hidden inside it.
The child it lands with
The one who has already met Tesla on the internet and arrives with opinions. That child is the reason to buy this book, not the reason to skip it, because the book is soberer than the videos.
The one who takes the back off things. The one currently loyal to an underdog, who would rather read about a man who lost his money than a man who kept his. And the child who is ready to be told that a real invention is a specific piece of physics and not a mood.
One place to stop and talk
This book needs more talking than most, and not about the science. It needs talking about where stories come from.
Somewhere your child will meet the fifty thousand dollars. The story goes that Edison promised Tesla that sum for redesigning a set of generators, Tesla did the work, and Edison laughed and called it an American joke. Stop there. That story comes from Tesla, in his own account of his own life, and no second person is on record saying it happened. It may well be true. It is also exactly the kind of story a man tells about the boss he walked out on. Ask how they would check it.
Then there is the tower on Long Island. Tesla raised money to build a tower that would send both messages and power through the earth and the air without wires. He never finished it, and the wireless power half was never shown to work at any useful scale. Online it is nearly always told as a miracle that got suppressed. It is more honestly told as a man who was right about several enormous things and wrong about this one, and who stopped being funded once his backer worked that out.
The last one is radio. Your child will be told flatly that Tesla invented radio and Marconi stole it. The patent history is a genuine tangle, several people held pieces of it, and a court did later cut back some of Marconi's claims. Cutting back one man's patent is not the same as handing the invention to another man, and it is almost always retold as though it were.
None of this makes Tesla smaller. He built the thing your walls are full of. But a child who learns to ask who told me that, and how would they know, has taken something out of this book worth more than the electricity.
What to know going in
The end is hard. Tesla dies poor and alone in a hotel room, and the last stretch of his life includes obsessive rituals, real paranoia, and a mind that is plainly not well. The book does not hide it and should not, but a child who has spent a hundred pages admiring him will feel the drop. Nothing in it is violent or frightening. The weight is sadness, and it is worth being in the room for the last chapter.
The second thing is the framing. The publisher's own copy calls him part mad scientist, which is the register the whole culture keeps him in. This book leans on the eccentricity more than on the work, and that can leave your child with a Tesla who is interesting instead of a Tesla who was right about something specific. Filling that gap is why this note is long.
Where to get it
The paperback is $6.99 at Who Was Nikola Tesla?, on the Stealth Science shelf. My honest advice is not to buy this one alone. Buy it next to Who Was Thomas Alva Edison and read them a week apart, because a child who reads only one of the two will believe it.
If your child liked this one
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Who Was Jane Goodall? What She Actually Figured Out
Who Was Jane Goodall? by Roberta Edwards
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Who Really Killed Cock Robin? A Food Web as a Suspect List
Who Really Killed Cock Robin?: An Ecological Mystery by Jean Craighead George
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Browse every book we have written about by age, by kind of book and by subject: Find the right book for your child. Or see the whole Stealth Science shelf.
