Although able to diagnose hydatid disease he thought the condition arose because ‘some people have hydatic constitutions.’

Cases in Surgery
In 1772 Hill published  Cases in Surgery a summary of his lifes work as a surgeon. Cases deals with the infectious disease sibbens, with cancers and with ‘disorders of the head from external violence’. Sibbens
Sibbens is now known to be endemic syphilis, a Treponemal infection spread by non-sexual social contact and seen in association with deprivation, especially overcrowded living conditions, poor sanitation and malnutrition. Hills account is written ‘to rectify the mistakes’ in the MD thesis on the topic submitted to the University of Edinburgh on the topic by Adam Freer in 1767. Hill concluded that syphilis and sibbens were the same disease and that sibbens, having been introduced into a family by sexual means, could then be transmitted around the family by close non-sexual contacts, giving his own family as an example of this mode of transmission. His apprentice Benjamin Bell, who was the first to show that syphilis and gonorrhoea were different diseases, also subscribed to this mode of transmission. Hill, like Freer before him and Bell after him, believed that the most successful treatment was mercury, supplemented on occasion by Peruvian bark. Hill was clear that sibbens and what he termed West Indian yaws were distinct diseases. Subsequent writers credited Hill and his physician colleague and friend Dr Ebenezer Gilchrist (bap1708-1774) with providing the most precise description of the clinical features and natural history of the disease in Scotland.
He later wrote "There was no infirmary in Edinburgh when I served my apprenticeship there, so that I never had an opportunity of seeing a cancerous breast extirpated or any other capital operation performed till I performed them myself." The first teaching hospital (the "Little House") opened opposite the head of Robertsons Close on 6 July 1729. Hill joined the Royal Navy as a surgeon in 1730. At this time naval surgeons were certified for the purpose after an examination by the Court of Examiners of the London Company of Barbers and Surgeons and many naval surgeons of the day had no other formal qualifications. Surgical practice in Dumfries
In 1732 Hill returned to Dumfries where he set up in surgical practice. On 28 January 1733 he married Anne McCartney, whose father John owned the Blacket (or Blaiket) estate, in the Parish of Urr and it was there that they established the family home. His practice was conducted from his town house in Amisfields Lodging in the Fleshmarket, in Dumfries. There is no known portrait of James Hill but Murray provides this description: "... his height being about five feet eleven inches. He continued till his death to prefer that fashion of dress that had prevailed in his youth. He wore a full wig ; and used a large staff. He was a man of dignity both of appearance and manners." Between 1742 and 1775,  Hill trained sixteen surgical apprentices.