The first, simplest puzzle is with the building right near where you start, on the left. This one has a circle in the window. There's a porthole right near it. Go down into the porthole. You'll see you're trying to get to a door, but it's blocked. OK, go back up the ladder.

Now look over at the edge of the 'rock' you're on, and you'll see another ladder going down the side. Go down this second ladder and you'll see a series of levers. In essence these levers raise and lower that platform you were just on before by the door. You want to raise and lower them until the rolly tihng rolls to the far left, so it's not blocking the door. This should just take 3 or 4 pulls.

Back around to the platform. Open the door. You can't go in because there's no floor. Lucky you, there's a rolly thing right outside that makes a lovely floor :)

Go back around to the levers. Adjust them so the rolly thing rolls right into the door. Now you can go back around and stand on it to look at the object inside. You can't use it yet, but this is where you can get to the first world once you get in to where Saavedro is. The key to unlocking the book is in there.

This book leads to Amaterin. The code is 11:00, 4:00, 6:15, 8:45.

The Myst 3: Exile Walkthrough