Harker published over a dozen research articles in the field of chemistry and was a Fellow of the Royal Australian Chemical Institute.
He was educated in Melbourne until the family moved to Petersham, New South Wales, where he attended Newington College (1892–1895).
[6] Whilst still studying, Harker was appointed as a demonstrator in chemistry at the University of Sydney and in 1901 he became a science teacher at Hawkesbury Agricultural College.
He was then awarded an 1851 Research Fellowship for study in England[7] and in 1903 received a Doctor of Science (DSc) from University College, London.
In his final years before retirement, Harker returned to teaching science as a master at Trinity Grammar School (New South Wales).