+DEFINITION.--A _Phrase_ is a group of words denoting related ideas, and
having a distinct office, but not expressing a thought+.

+DEFINITION.--A _Preposition_ is a word that introduces a phrase modifier,
and shows the relation, in sense, of its principal word to the word
modified.+

Analysis and Parsing.

1. The pitch of the musical note depends upon the rapidity of vibration.

TO THE TEACHER.--See suggestions in Lesson 12, concerning the use of
diagrams.

pitch depends
==========|=================
\The \of \upon
\ \
\ note \ rapidity
\-------- \------------
\the \musical \the \of
\
\vibration
\---------

+Explanation+.--The diagram of the phrase is made up of a slanting line
standing for the introductory word, and a horizontal line representing the
principal word. Under the latter are drawn the lines which represent the
modifiers of the principal word.