Earlier in the book, we looked at chords voiced in 4ths. It is also possible to harmonize melodies in 4ths or to use them as embellishments to a melody or chord progression. Here are the fingerings for 4ths across each pair of strings, along with an example of how to use them.
Here are some of the ways 4ths might be used in a song.
This one combines the sound of 4ths with 6ths and 3rds.