Fifth Sister had sent it over herself. Even if it was just a toy, it could not possibly be something ordinary.
Yun Chuhuan's anticipation soared.
"If it turns out to be less impressive than the sword you gave Cen Yiyi, I will not let it pass!"
"Rest assured. You will definitely prefer this toy over that sword."
Yun Shu lifted an eyebrow.
This boy had once been sent by Imperial Father to train in martial arts. After squatting in a horse stance for barely the time it took to finish a cup of tea, he had come wailing to seek out his Consort Mother, refusing to learn any further.
Given that, how much could he truly like swords?
Even if it was purely a matter of collecting, his enthusiasm was fleeting at best. A whimsical toy would easily outshine any short-lived fondness he had for swords.
Yun Shu promised with full confidence.
"Just wait. Before I give the sword to Yiyi, I will make sure you receive your toy first."
"You said it yourself!"
Yun Chuhuan's eyes lit up instantly.
"I knew it! I'm clearly Fifth Sister's favorite little brother!"
Yun Shu said nothing.
Well, truth be told, she only had one little brother for now.
…
Since she had promised to gift Yun Chuhuan something, after the seven-day holiday ended, Yun Shu sent the blueprints and methods for using the steam engine in steel refining to the Ministry of Works for trial development. Along with those, she slipped in the designs for the little toy she intended for Yun Chuhuan.
She had assumed that, bearing the name of a "toy," her blueprint would not attract much attention at first.
But that very afternoon, in the Imperial Study, she heard that Ye Qing'an had come to request an audience.
"You said Ye Qing'an came not to see Us, but to see the Crown Princess?"
Upon hearing Li Dehai's report, Emperor Xuanwu's first reaction was suspicion. Had his daughter stirred up another grand commotion behind his back?
He instinctively turned to Yun Shu.
"What have you done this time?"
"Your Daughter has done nothing," Yun Shu replied, lifting her gaze with an air of innocence.
"I merely sent a blueprint to the Ministry of Works, asking if they might test using steam engines for steel refining."
"Steel refining with steam engines?"
Though Emperor Xuanwu did not fully understand how a steam engine could be involved in refining steel, he had already seen the power of the steam-powered carriage.
Now, hearing the words "steam engine" again, he instinctively felt this must be another marvel of ingenuity.
His expression brightened.
"Summon Ye Aiqing in at once!"
"Yes, Your Majesty."
Li Dehai withdrew with a bow. Before long, a figure clad in a green official's robe entered in hurried steps.
Although his attire remained unchanged from the past, Ye Qing'an's entire bearing had subtly shifted, like a scholar transitioning from the path of letters to the realm of mechanics.
He entered with composed urgency and bowed deeply before the two royals.
"This humble official greets Your Majesty, Crown Princess."
"You may rise."
Emperor Xuanwu, still keen on hearing what Ye Qing'an wished to ask, especially if it pertained to steam engines, quickly motioned for him to stand.
"We heard you came today not for Us, but for the Crown Princess?"
"Yes, Your Majesty," Ye Qing'an replied respectfully. "This humble official had a few questions about the little train and wished to consult Her Highness."
"Little train?"
Not the steel-refining steam engine?
What was this little train now?
A vehicle powered by fire? Could it even carry people?
Emperor Xuanwu looked baffled and turned once more to Yun Shu.
"Did you not say you only handed over blueprints for steam refining?"
"The main blueprint was indeed for steel refining using the steam engine," Yun Shu explained earnestly. "As for the train blueprint, that was merely a small gift for Sixth Brother."
"That is no mere gift!"
Ye Qing'an could not restrain himself and interjected.
"This humble official studied the diagram for a long while today. It occurred to me that if this design were scaled up, it could deliver military rations across Tian Sheng at unprecedented speed—with almost no loss of supplies in the process."
"What?!"
Emperor Xuanwu was utterly shaken.
The ability to rapidly transport rations—what did that mean?
With adequate funds and resources in the national treasury, it would resolve one of the most critical wartime concerns: timely supply of food and military goods to the frontlines.
Most crucially, Ye Qing'an had even claimed there would be virtually no loss of provisions during transport!
That alone was enough to make Emperor Xuanwu's mind reel.
In current practice, food convoys needed not only protection against theft but also people to escort the delivery—people who consumed food along the journey.
Spillage, exposure to rain, spoilage on the road… so many factors led to losses. If sixty to seventy percent of the food made it to the battlefield intact, that was already considered exceptional.
But now, if this transport method could truly eliminate losses…
Emperor Xuanwu suddenly stood, nearly overcome with urgency. He wanted nothing more than to grab Yun Shu by the shoulders and shake the knowledge from her head, to learn every detail instantly.
"What exactly did you give that boy?"
"It really is just a small gift."
Yun Shu gestured with her hands, forming the size of a bath barrel.
"The carriage is about this big—split into two compartments. Just enough for Sixth Brother and his companion to each sit in one and play."
"This humble official came today precisely because of that!"
Ye Qing'an hurried to follow up.
"In this official's opinion, the carriages could absolutely be built larger, longer, and with greater capacity!"
"Wait. Split into two compartments?"
Emperor Xuanwu had not yet seen the blueprints and was starting to grow confused.
"If the train is in two parts, how is the one at the back controlled?"
"By the tracks, naturally," Yun Shu replied without hesitation.
"One must first determine the route along which the little train is to travel. Once the tracks are laid, the train will follow them precisely.
Regardless of how many carriages are attached, it will not stray from its course. It proceeds in steady fashion along the path set in advance."
"You mean to say we must first build a special road just for this train?"
The cost. Would it not be exorbitant?
Some of the heat faded from Emperor Xuanwu's eyes.
"So, if we wanted to use this so-called little train to transport supplies to the border, we would first have to construct a path from the capital all the way there?
"That would hardly be as flexible as the steam carriage."
"Even if wars did break out across the land in the future…
What if a war could be concluded in three months? Would the track even be finished before the conflict ended?
And once peace returned, what use would a track to the border serve?
Would it not be a complete waste of funds?
No wonder Xiao Wu had simply treated it as a toy to gift her little brother.
She must have considered that as well."