Simplify the following text for a Grade 8 native English-speaking person.
Original: Sir Edmund Barton , GCMG , KC ( 18 January 1849 â `` 7 January 1920 ) , Australian politician and judge , was the first Prime Minister of Australia and a founding justice of the High Court of Australia .
Simplified: Sir Edmund Barton ( 18 January 1849 â `` 7 January 1920 ) was the firstPrime Minister of Australia .