Chapter 25

* Chapter Cover
* WSJ Cover

**By These Hands, the Light of Science** (この手 (て) に科 (か) 学 (がく) の灯 (ひ) を, *Kono Te ni Kagaku no Hiwo*) is the twenty-fifth chapter of the Dr. Stone manga.

## Summary

Atop the bald mountain, Kohaku has set up the makeshift lightning rod (made of Kinro's golden spear) just in time for it to be struck by lightning. Gen is struggling to come to terms with the magnitude of the accomplishment they are pursuing with no setbacks.

Senku retrieves the iron rod and proclaims that electricity is on it's way. The group gathers at the summit as the clouds disperse giving way to rays of sunlight. Kinro is devastated seeing that his precious golden spear has been mostly disintegrated by the current. Kohaku apologizes for it, while Ginro takes the chance to tease him about it, and gets a few dents put on his head.

Kohaku decides to try out the magnets, and gets exhaltated when they refuse to stick together, being pushed apart by a mysterious force. Senku corrects her about having the poles the wrong way around, and they snap together. They succeeded in making magnets.

Chrome is excited to make electricity, Gen snarkily inquires about what will power the generator, would it be fuel?, wind? perhaps even nuclear power?; turns out it's muscle power.

They cast copper disks that they hammer down into thin, large copper sheets. The sheets are cut into large copper disks, mounted on an axle, and their edges are ground smooth using corundum, by Suika and Kohaku.

Senku coats copper wires with lacquer, explaining what he's doing to Gen, who finally gives up and asks him why his face has been swelt all this time. Lacquer poisoning, Senku says.

By night time, their dual hand-cranked dynamo is complete. Chrome finds it so flimsy he remarks that they need two people to spin it in sync or it will shake itself apart. Trying to think of good candidates for the job, their minds land on Ginro and Kinro. Gen steps in and ultimately buys them with a lie about how it's possible to use electricity to make and repair gold and silver spears. Kinro was more reluctand but gave in never the less. This move was questioned by Senku and Kohaku, the former questioning him about whether he's aware of the shortcomings of electroplating, Gen just made everything up.

The brothers pour their hearts spinning the dynamo, and Senku is very pleased with how his Kingdom of Science grows. Not seeing any result of their work, Gen wonders if they'll really get electricity out of it. He is presented with a carbonized bamboo fiber before Senku and Chrome climb atop the shed with cables. Gen doesn't get what is going on, until Senku connects the fiber across the wires.

A realization came rushing back to Gen's mind. Japanese bamboo made the filament of Edison's light bulb. Atop the shed, Senku asks Chrome if he's afraid of the dark, he says that he logically is, and asks why this question. He explains that back in his age, there was no darkness to be afraid of, the 24 hours of the day were conquered by Edison's electric light.

As the connection is made, the kingdom of science is bathed in a bright white light, lasting for a brief but intense moment, after thousands of years.

As everyone winds down from this event, Gen reflects on what this means for his allegiance to Tsukasa. Senku tells Chrome about his childhood, and how the first biography he ever read was of Thomas Edison, leading him down a path of fascination with electricity. After waking up bare naked in the wild, he is overjoyed to have it back, and so is Chrome.

## Characters in Order of Appearance

* Senku Ishigami
* Kohaku
* Chrome
* Gen Asagiri
* Kinro
* Ginro
* Suika

## Chapter Notes

* The kingdom of science succeeds in making magnets with lightning.
	+ Magnets have a polarity and their relative orientation determines if two magnets attract or repel.
	+ They can be used to craft dynamos/generators.
* Senku has a strong allergic reaction to lacquer.
* A dynamo is crafted by the kingdom of science, which is hand granked by Kinro and Ginro. Electricity acquired !
	+ The brothers join the Kingdom of Science.
* While possible to electroplate spears with gold and silver, it's not an easy process.
* Carbonized bamboo was the filament of Edison's lightbulb. They lit one up in the open air and it burnt away quickly.
* Chrome is afraid of the dark.
* Senku read Edison's biography as a boy in school.

## Trivia

* In the cover page, Senku is holding a staff that has a primitive electric motor in it.
* Although Kohaku untied her hair in order to use the rope to attach the iron rod to the spear in the previous chapter, as she is landing from her jump at the start of this chapter, her hair is tied again while the rod is still tied to the spear.
* Kurita Ryoukan from Eyeshield 21 makes a cameo as Senku admits the dynamo will be muscle powered.
* The dynamo they made is a set of two greatly oversized Faraday disks wired in series. The Faraday disk is a homopolar generator that produces low voltage DC. Although simple in construction, it's highly inefficient, and without large modifications, was never a practical power source, which has also been verified by scale models built by fans.
* The panel in which the flow of electricity through the cables of the generator is shown, shows the flow coming out of the negative side and into the positive side. This is consistent with electron flow, and not with conventional current as it's conceptualized and measured in electrical or electronics engineering.
* The breakthrough that was Edison's bamboo filament bulb that made it vastly superior to its predecessors was its high electrical resistance, making a poor choice to run on a low voltage generator, as little current would flow.

## Site Navigation

1. ↑ Sammzor's replica generator on Youtube
2. ↑ Difference between conventional current and electrion flow at electricaltechnology.org