turn up the collar ...

We must make ourselves as invisible as possible." Bearing against the mirror, after a short silence, he said: "It takes some time to release the counterbalance, when you press on the spring from the inside of the room.

It is different when you are behind the wall and can act directly on the counterbalance.

Then the mirror turns at once and is moved with incredible rapidity." "What counterbalance ?" asked Raoul.
"Why, the counterbalance that lifts the whole of this wall on to its pivot.

You surely don't expect it to move of itself, by enchantment! If you watch, you will see the mirror first rise an inch or two and then shift an inch or two from left to right.