This is a graph of the word sentiment in The Wizard of Oz and the Land of Ox. Each bar represents the relative sentiment over ten lines of text. It is difficult to make out the story arc because we are seeing more noise than underlying patterns.
In this graph, each bar represents the relative sentiment over fifty lines of text. The patterns are clearer, but still we are lost in the details and missing the forest for the trees.
In this graph, each bar represents the relative sentiment over one hundred lines of text. At this level we can see a clear pattern in the text: both stories follow a conventional adventure narrative. A happy beginning is followed by a series of events, which go back and forth between positive and negative, and then there is the standard happy ending; although the final lines of "The Wonderful Wizard of Oz" go negative again, perhaps because of the description of Dorothy's abrupt and bumpy flight home. It's interesting though that the overall sentiment of the text is distinctly more negative than positive. Perhaps the popular perception of Oz as a fun children's world comes more from the movie version of the story, which is both light hearted and musical. In contrast, the original texts emphasize a number of disturbing and frightening plot elements. They show more resemblance to the harsh moral world of Grimm's fairy tales than to contemporary children's entertainment in the style of Disney.