This diagram refers to chapter seven from Alice in Wonderland. The diagram splits up the chapter first into sentences and the word quantity within them, which is represented by the single arms coming from the centre.

It is further split into how many words have, one letter, two letters, three letters and so on. This is represented by 1 word: 1 cm. One letter words start at 0 degrees, then the circle is split into the relevant sections depending on the maximum letter count for that sentence.