Complex sentence: After teaching in Zurich for some years, John became music master and violin teacher at Harrow in 1862 as a result of being noticed while giving piano demonstrations at the 1862 London International Exhibition.
Split into simpler sentences: After teaching in Zurich for some years, John became music master and violin teacher at Harrow in 1862. Farmer was reportedly appointed as a result of being noticed while giving piano demonstrations at the London International Exhibition.