Hardie specialised in the diseases of women and children, particularly those arising from climate. In 1893, he became president of the Medical Society of Queensland, which became a branch of the
British Medical Association, the predecessor of the
Australian Medical Association. On a visit to Europe in 1895 (with his wife and 3 children) he investigated
Röntgen's work on
x-rays but although he brought radiology equipment to Australia he did not pursue the work. During this trip he spent some time back in
Moray with his ailing father, and also with his elder brother John's family at Westerton Farm,
Pluscarden. In 1902 he built Firhall in Wickham Terrace where he resided and practised. Hardie was a capable family physician and popular with patients in all levels of society. He won many distinctions and became Queensland president of the
British Medical Association in 1910 and 1920. He was a foundation member of the
University of Queensland Senate between 1911 and 1916 and chaired the Emmanuel College Council from 1911 to 1940. He joined the
Royal Army Medical Corps and served with it in France in 1915–16. Hardie was a staunch Presbyterian and after the war he became the first chairman of the
Presbyterian and Methodist Schools Association. He was an honorary physician for years to the
Hospital for Sick Children, the
Lady Bowen Hospital and the
Lady Lamington Hospital and also served on the Central Board of Health from 1894 to 1915 and the Medical Board of Queensland from 1894 to 1934. He published numerous journal articles and one book in 1893, Notes on Some of the More Common Diseases in Queensland in Relation to Atmospheric Conditions. Hardie retired from active practice in 1922 and investigated the treatment of
tuberculosis in
England and
Switzerland in 1922 and 1923 on behalf of the Queensland government. In 1927 he became a founding fellow of the
(Royal) Australasian College of Surgeons. From 1928, he helped form the Rev.
John Flynn's
Aerial Medical Service of the
Australian Inland Mission (now the
Royal Flying Doctor Service) and fostered the development of
Alfred Traeger's
pedal radio. == Later life ==