Trabenum: creates a mild wind tunnel.

How bad could it be? Ron thought. He rolled up his sleeves and waved his wand.

"Trabenum..." he whispered, and the entire library thundered and shook.

"Ron!" Hermione yelped. Three windows across the room from Ron shattered into the room and the window behind him shattered outside. For half a second, he experienced an immense wind power before his chair flipped back and his head hit the wall. The wind stopped after a few seconds. Ron pushed himself up and the room spun around him. He glanced at the carnage and vaguely saw Hermione waving her wand at the rubble. Something about her face told him she was yelling at him, but all he could hear was a loud ringing.

He stepped into the hallway and Hermione's angry scream suddenly found its way through the ringing and bounced back and forth inside his skull. Clutching his left hand to his forehead, he kicked the bathroom door open. He ran the tap and splashed cold water on his face. As he started to regain his senses, his nose caught the smell of freshly cut grass. For a second, he worried he banged his head too hard. This bathroom was nowhere near any grass. But as the throbbing pain in his head eased up, he splashed water on his face again and walked back to the library.

His desk was now buried in a pile of dust. Hermione was consoling Irma, the librarian, who would lose her temper over anything louder than a whisper. As the first magical research team at Hogwarts, Harry, Hermione, and Ron went through books, artifacts, mysterious spots around the school, and a lot of sophisticated magic. Since Hermione exptected accidents, she insisted that new spells be tested in a safe place. Ron knew he made a mistake but wasn't ready to deal with it.

Ron moved his eyes away from his battered desk and caught Harry smirking at him.

"Glad it wasn't me this time."

"As you should be ..." Ron said and tapped his wand on his desk to clear away the dust, picked up a notebook and a piece of parchment and put them under his left arm. He turned to spot Hermione and walked over to where she sat next to Irma. Irma's face showed nothing but fury.

"I'm sorry Ms. Pince. This won't happen again. I promise." Irma didn't move a single hair. Ron glanced to his side and locked eyes with Harry. Harry nodded. Ron didn't know what Harry meant. But before he could think about it any further, Harry spoke.

"Ms. Pince," Harry's voice sounded unexpectedly giddy, "me and Ron wanted to surprise you with this later, but I guess It's time." Irma tilted her head up, suspicious of Harry's intentions. Hermione squinted at Harry's words. She couldn't think of anything that Harry and Ron had worked on together lately.

"Ok. Stay where you are," Harry ran to the other side of the library, further upsetting Irma. She insisted that one must move gracefully in the library at all times. Harry realized what he did when he saw Hermione shaking her head on his way back.

"I hope you don't kill me before you see the results," Harry expected at least a chuckle, but he got none of that. "Let me demonstrate," he opened the book he brought back with him to a random page and held his right hand to his chin, as if thinking about something.

"Ron, do you remember the spell you found that did nothing?"

"Which one?"

"The one you cast on Marvels of Dark Architecture," Harry chuckled. At that, Irma's face turned a velvety shade of red. Casting a spell on a library book was unforgivable. She was only biding her time before the silly display was over. How can they not know what bothered me after all these years? Are they really that stupid? No. They will not be forgiven for this.

"No way! You got that to work?" Ron was oblivious to Irma's rage, and so was Harry.

"Behold…"

Harry paused for a few seconds without moving or saying anything.

"Page seven hundred. That's a suitable number."

"For what?" Ron asked.

Harry grabbed the open page and ripped it off. Hermione gasped and Irma stood up in shock, her face now a deep shade of purple. Harry held his ground and tossed the ripped sheet into the air. Irma opened her mouth, completely losing her temper, but she froze in the middle of the first curse-word she intended to utter. She searched for the torn page all around, up in the air, behind the nearest shelf, but it wasn't there. Her mouth slowly closed and she remained silent. She turned back to Harry and saw a smug grin on his face. His index finger pointing to something on the page. Irma reluctantly peeked. Page seven hundred. Perfectly intact. Now she was completely frozen, on the edge of tears. Irma's face exuded a full rainbow of emotions.

"Harry! How did you do this?" Hermione beamed. This gave Irma some time to get herself together.

"Oh you know…" Harry said.

"I don't, actually..."

"How easy is this to reproduce?" Irma interrupted with a shrill voice..

"A wave of a wand…" Harry smiled.

Irma could barely control her emotions, so she lurched forward and pulled Harry into a rib-crushing hug.

"You don't understand how great this is," Irma paused, a small tear forming on the edges of her eyes. She turned to look at Ron, a warm smile on her face, "please don't wreck my library again," and she spoke with a gentle voice Ron hadn't heard before.

"I won't," Ron smiled.

"I'll have to leave now. I trust you three will handle the cleanup," Irma said as she walked away, not waiting for an answer. Those brats will wreck my library again, I'm sure of it. But for once, I hope they do it again. Eternally pristine books... Can it be? It was the best news Irma heard in her entire career as a librarian.

Harry watched Irma walk away for a few seconds. He turned back and saw Hermione holding her arms on her sides and a smile on her face.

"And how does that spell work, if you don't mind explaining?"

"If I tell you, can I skip the cleanup? I'm almost late for my students," Harry grinned.

"Fine," Hermione's curiosity forced her to give in to Harry's extortion.

"So I don't know exactly how it works—" Harry stopped when he saw Hermione roll her eyes. "If you don't want to hear it..." He pretended start cleaning up. Hermione grabbed his left shoulder and turned him back to face her.

"Ok I promise I won't say anything," she snickered under her breath.

"The charm binds the book in time, and it only works for books."

Hermione gaped, "woah, That's really impressive, time-turning spells are very difficult."

"Blimey, it's a time-turner?" Ron chimed in.

"I found a detailed description of it in volume four of Chadwick's Charms," Harry continued.

"There's no volume four, so which one was it?" Hermione asked. Harry didn't say anything. He only smiled. Hermione's jaw opened to a full drop.

"You didn't..."

"I did," Harry kept smiling, "I have to go now, I'll show you later." He walked back to his desk in a haste. He stashed his wand in his pocket, a bad habit he never managed to get over, then he picked up his notes and cup of coffee. He turned back and his eyes widened. He looked at a a sparkling clean library. Hermione shrugged. Harry shook his head and walked out the door. Of course, Harry knew that Hermione knew more than most wizards combined. He was amused that he'd found something she didn't know.

"Thanks Harry!" He heard Ron's voice from the distance.