I had these two fiddle tune books since early 1960s. I understood it to mean the following. There are various decorative devices you can use to embellish a simple tune. We call them grace notes and such these days. Even most rural fiddlers would have been familiar with the sound and use of the majority of them. They are commonly used on other instruments too and it seems they always have been. I assumed that the little device that decorates the principal note by using the next higher note was called "a raise" and the one which uses the note blow was call "a drop". We call them mordents. I am sure that they had other names for decorations which died out with rural fiddling as the taste for Italian, French and German culture progressively engulfed the old English country life back in the early 1800s.