When playing Call of Cthulhu, in chapter 8 you will reach Dr. Fuller's office. Upon entering it, you will find a model of a ship - in order to reach it, follow the wall on your right. There is a puzzle to solve there - set the ship's masts properly, in order for them to face the ship's bow.
You can maneuver three masts - turning one of them changes the direction the remaining two are facing. In fact, this is a simple puzzle to solve after several attempts. Nonetheless, you can use the following method to turn the masts (1 to 3, counting from left): 2, 2, 1, 3, 1, 3, 3, 2, 1,3, 2, 2, 1, 1, 2, 3, 3, and finally 2.
This way, the masts are set properly and you activate a reconstruction pushing the story forward. For solving this puzzle, you receive the White Ship.
Note: Surely this is not the only combination available. This is just an example - you can solve this puzzle by turning other masts as well.