You have to set everything in correct order and push the big middle button to solve this puzzle. Look closely around the area to find all seven switches for the valves. Every switch has one symbol.

Did you find the piano?

Every key in the piano corresponds to a three digit number. Nora will write these down into the journal.

Right from the piano, in the box, is a paper that links symbols to the piano keys. Those are the same symbols that are in the organ.

You just have to find out what keys, or numbers, or hertz, to put on in the organ.

Here you can find the three numbers.

You have the numbers

262 Hz ... 349 Hz ... 415 Hz

Those hertzes correspond to the piano keys, and to the symbols.

Have you gone through the papers in the camp.

There's mentions about how the sea level affects the organ.

Walk right from the organ, stairs down. There you can see symbols indicating the height of the tide.

Those symbols were presented somewhere else, also.

Look trhough the slideshow with the projector.

This slide is particulary interesting.

It tells you how the symbols should be tuned according to the tide height.

So, turn on the symbols for 262, 349, 415 turned into correct ones.

The organ should look like this:

Click the button.

The round hole should be in correct position, also.