The first guitar part, you strum up at the 3rd first and down on the two last

    Em      Em
e|--0-------0-
B|--0-------0-
G|--0-------0-
D|--2-------2-
A|--2-------2-
E|--0-------0-

      Em     E
------0------0
------0------0
------0------0
------2------2
------2------2
------0------0

m  Em
---0----------
---0----------
---0----------
---2----------
---2----------
---0----------

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Part number two is really banjo. But can be translated to guitar like this; 
but 
if you listen to the song you can hear that there are twice as many strokes. Again 
because it`s the banjo.

e|----0-0--2-3
B|-0----------
G|------------
D|------------
A|------------
E|------------

--2-3--0------
---------3--0-
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--------------

------0--2-3--
3--0----------
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--------------

2-3--5-7-3-7--
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--------------

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e|-7-7-7-3--5-
B|------------
G|------------
D|------------
A|------------
E|------------

5-5-2--3-3-3-0
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--------------

--2-2-2--3--5-
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-7--5--3--2--0
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-0-0---0-0-|
-----3-----|
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Part three is also banjo and is just like part two but deeper and i s the main theme.

e|------------
B|------------
G|-----------0
D|-----2-2--4-
A|--2---------
E|------------

--------------
--------------
-0------------
4--2-0---0----
-------2------
--------------

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--------------
----------0--0
---2-2--4--4--
2-------------
--------------

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--------------
--2-4-0-4-----
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--------------

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e|------------
B|--0-0-0-----
G|--------0--2
D|------------
A|------------
E|------------
Part four is a

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-2-2----0-0-0-
-----4--------
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 guitar part t

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----------0-2-
2--4-4-4------
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he ryhtm part 

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0-------------
--2-0---------
------4~--2-2-
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(the verse and

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2-0-2-2~--|
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 chorus)

[this is the c
     Em    G  
e|---0-----3--
B|---0-----0--
G|---0-----0--
D|---2-----0--
A|---2-----2--
E|---0-----3--

hords]
   Bm    D
---2-----2----
---2-----3----
---4-----2----
---4-----0----
---2-----x----
---x-----x----

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 Em
When on the road to sweet Athy,
 G
Hurroo Hurroo
 Em
When on the road to sweet Athy,
 Bm
Hurroo Hurroo
 
 G                  D
When on the road to sweet Athy
 Em                  Bm
A stick in the hand, A drop in the eye
 G         D     Em      Bm
A doleful damsel I heard cry
 Em
Johnny I hardly knew ya

That goes all the song.
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