Father and Son, United in Purpose

"Get a few guns ready, we're going to the shooting range."

Joseph gestured to Martinier, and was about to pick up the newly completed Bulletproof Insert to conduct field tests when he heard Eman say from the side, "Your Highness, His King has arrived."

Joseph turned around and saw Louis XVI walking into the shed with a smug smile, "Hmm, my dear Joseph, I bet you've invented something interesting to be here."

Then he muttered somewhat resentfully, "Why didn't you call me to come along? We're the best partners."

"Oh, never mind, let me see what good stuff my genius son has come up with this time..."

However, when he took the Bulletproof Insert from Joseph, he frowned slightly. "This is... a piece of iron?"

"This isn't just a simple iron plate," Joseph said, pulling his father toward the shooting range. "It can withstand bullets."

Louis XVI incredulously weighed the Bulletproof Insert in his hand. "This thing weighs at most 3 pounds, oh, the standard measurement has changed now, it should be 1.5 kilograms, and it can actually stop bullets?"

As a "science and engineering geek," he has some knowledge of armor. Even a breastplate weighing over 10 kilograms can often be penetrated if the bullet is fired at a perpendicular angle.

The Crown Prince actually wanted to use such a thin piece of material to block bullets!

You'll see when you see it.

Joseph gave his father a mysterious smile, then instructed the guards to attach the Bulletproof Insert to the wooden target, and then took a Percussion Cap Gun from Martinier- Neill—a newly produced Royal Armory, which had just been calibrated.

Joseph moved to a distance of 60 paces from the target, pulled back the bolt, attached a Percussion Cap, and squinted at the Bulletproof Insert in the distance.

With a loud "bang," the target was missed.

Joseph awkwardly reloaded and fired again.

"Bang!" Still missed the target.

It wasn't that he was a bad shot; in the era of Smoothbore Musket, whether you could hit someone at 60 paces was largely a matter of luck.

Finally, after the third firing of the Percussion Cap Gun, the Bulletproof Insert in the distance visibly trembled.

Two soldiers from the firing range immediately ran over and carried the target over.

Louis XVI went forward to examine it out of curiosity and saw that the iron plate was dented in a large area, but it was clear that it had not been pierced through!

He looked at Joseph in shock. "How is this possible? It's only such a thin piece!"

Joseph was not surprised at all; he had set the firing distance at 60 paces, leaving a considerable margin. According to his plan, the breechblock should be able to stop the fire of the British Brown Bess 1777 Flintlock Gun from 30 paces away.

He smiled as he removed the Bulletproof Insert from the target and explained to his father, "Dear Father, this isn't actually just a piece of metal."

He pointed to the metal plate, which was partially broken by the impact. "You see, behind the metal plate is a ceramic plate."

"A porcelain shard? What use can something so brittle be?"

"To disperse the impact of the bullets," Joseph said. "You can see from the edges that the porcelain shards are broken."

"Because the crack extends horizontally, it can disperse the vertical impact force into the horizontal direction."

"And behind that is a layer of silk. Silk is extremely tough and can hold the first two layers in place, preventing them from being torn apart by sudden deformation."

"As for the last layer of metal, it's used to improve reliability. You see, there are only slight marks on it."

Louis XVI's eyes widened as he examined the Bulletproof Insert in his hand, nodding repeatedly. "The simplest structures often possess unexpectedly superior performance. Joseph, how did you come up with this idea? It's simply... simply ingenious!"

Joseph thought to himself that he must have seen it in a documentary, but he still followed his usual routine and made the sign of the cross. "I think this must be a revelation from God."

Upon hearing this, Louis XVI immediately made the sign of the cross with utmost reverence. "Thanks be to Almighty God!"

Over the past two years, as his son has received continuous "God revelation," he has become a hundred times more devout than before.

Joseph, however, said something even more shocking, "These Bulletproof Insert should still have some force left. Let's close the distance to 50 paces and try again."

The new insert was secured. Joseph handed the gun to his father.

As thick smoke billowed from the muzzle, Louis XVI hit the Bulletproof Insert with a single shot, then raised an eyebrow at his son, who had only managed to hit the target three times before, with a hint of smugness.

The soldiers quickly brought over the target. Joseph rushed forward to check the shrapnel; the crater was deeper than before, but it still hadn't been penetrated.

He flipped the insert over and saw that the back of the last metal plate had only a barely noticeable dent, indicating that the wearer would not be in any danger.

Before he could speak, Louis XVI said first, "Perhaps, we could get even closer."

As the tests continued, the Bulletproof Insert was finally penetrated when the shooting distance was reduced to 28 paces.

Afterwards, Louis XVI and his son continued to test Bulletproof Insert made in several other ways. When it got dark, they slept together in the same bed at the Ordnance Factory and talked about various firearms and machinery until after 2 a. m.

Over the next few days, the father and son spent all their time in the Ordnance Factory, conducting a series of tests and improvements on all the different combinations and materials used for the Bulletproof Insert, and finally determining several types for mass production.

Joseph, looking at the production process documents in his hand, instructed Martinier: "Produce 6,000 units of the general-purpose type first. 2,000 units of the Heavy-Duty. 500 units of the premium type."

After several days of testing, he discovered that double-layered iron plates were completely unnecessary for dealing with 18th-century soft Lead Bullet.

So, on his father's advice, he used a structure made of iron, Cotton, ceramics, and silk to reduce the weight of the Bulletproof Insert to 1.05 kilograms, which could stably withstand Flintlock Gun fire from 40 paces away.

This "universal" Bulletproof Insert is the cheapest, costing only 5 Livre to 16 suls. If necessary, even the silk can be omitted, drastically reducing the price to less than 4 Livre, but the bulletproof range also drops to 55 paces.

The "Heavy-Duty" insert was the first structure tested previously. It consisted of two layers of iron plates, weighed 1.4 kg, and could only be penetrated by Flintlock Gun at a distance of 28 paces. It was specifically designed for cavalry use and cost 6 Livre to 10 sous.

The "premium" version features a single layer of iron sheet with a double layer of silk, weighing about the same as the standard version, and providing stable bulletproof protection at a range of 33 paces. However, it costs as much as 8 Livre and 5 sous, and is generally only issued to officers.

In fact, Joseph originally planned to produce more than 100,000 pieces and distribute them to all members of the Royal Guard Legion. However, the bottleneck of adhesive supply limited his ambitions.

While Casein Glue boasts excellent properties, it can currently only be produced in small quantities and is quite expensive. As for other natural adhesives, they are generally unusable in large quantities.

Joseph recalled the various Phenol adhesives of later generations, and his desire to quickly promote Gas Streetlight and thus illuminate the organic Chemical industry grew even stronger.