"I was staying with my aunt and uncle but Mister Hagrid says I won't be anymore."

The goblin nods.  "If your muggle guardians are inadequate you will be made a ward of Hogwarts.  Your guardian will be responsible for your vault key until you attain your majority, at which point ownership will officially pass to you."

"Okay. What does being responsible for my vault key mean?"

"You will need to keep it safe and produce it if you wish to enter your vault.  If you need to replace it you will need to alert the bank and be responsible for the fee."

She nods, seriously. "Can anyone steal it from me?"

"The object can be stolen but it would require nontrivial magic for someone to use it to open your vault if you or your guardian did not authorize it."

"Okay. I'll keep it safe anyways, though."

The goblin nods smartly and leans back in his chair.  "If that's all, I'll have someone take you down to your vault."

"Yeah, it is. Thank you, sir."

Teller-goblin calls over another goblin, who takes her and Hagrid through one of the doors opposite the entrance, down a hall, to what looks like a miniature underground train station.  They all three pile into a minecart and it rockets off.  Out of the minecart-station and into the mine, dark dank tunnels burrowed out of rock, cart track winding and swerving and coiling, zipping through fork after fork after fork in the way.  The goblin at the front of the cart, who seems to be controlling it, looks perfectly at ease; Hagrid looks a bit queasy.

Woah! (Harriet is hunkered down. She really doesn't like roller coasters! Let alone this! There's no seat belt!)

This at least does not go as wildly up and down as roller coasters, but it's still a fast and swervy ride.

Eventually though they come to another little minecart-station, set into the hewn rock walls of the mine, with an enormous, ornate circular metal door opposite the track.  There is, she can see, a little hatch in the center.

"Vault 687," the goblin says, "Potter-Evans."

She climbs shakily out of the cart and walks up to the hatch, squinting at it then inserting her key.

There's a sequence of thunks and kachunks as heavy complicated internal locks unlock themselves.  The door splits open down the middle, the halves slowly easing left and right into the stone.

Torches come to life inside the vault, a room the size of the Dursleys' living room.

There's gold.  There's gold coins in heaps on the shelves and gold bars stacked in pyramids on the ground.  There's artfully arranged stacks of silver coins, a few topped with finely cut gems.  Little bronze-colored coins in shallow bowls on the shelves next to the heaps of gold.  Pouches, that she can see must be stuffed with more coins.

!!! Woah! That's so much gold. (Harriet is struck a bit speechless.)

"Looks like enough to get you through seven years, don't it?" says Hagrid wryly.

"It's a lot..." Kinda feels like too much actually...

"We'll just take enough to buy your school supplies for today.  The rest'll be safe down here."

"Okay. How much is enough?"

Hagrid counts out some gold into a pouch for her.

She tries to keep track of how much gold he's counting out. "How much is that worth?"

"Hundred some-odd galleons is five-hundred-some British pounds - five pounds the galleon.  'S more than you need just for school supplies, but you'll need a wardrobe too, we left all yer clothes at the Dursleys.  And you should have some to spend on yourself."  He grins.

"That's a lot though..."

"Less than it sounds like," he says.  "Supplies get expensive, 'specially your first year.  Worried about losing it?  I can keep it safe for you, if you like."

"If you don't mind?"