Determine the rhyme scheme of "it is a beauteous evening, calm and free"

Alright reading the poem "Its is a Beauteous Evening, Calm and Free" by Wordsworth, we can conclude the rhyme scheme in the following way.
It's important to recognize that "thought" and "not" rhyme, as that is a common mistake made within this text.
 We can determine rhyme scheme by looking at the last word in the line. If they rhyme then they are the same letter, if not we add a new letter.
So doing so we can get:
Rhyme Scheme: 
Line 1 - a
Line 2 - b
Line 3 - b
Line 4 - a
Line 5 - a
Line 6 - c
Line 7 - c
Line 8 - a
Line 9 - d
Line 10 - e
Line 12 - f
Line 13 - d
Line 14 - f
Line 13 - e

Hope this helped :)