George Birnie's first appointment as surgeon-superintendent was to the Asia which departed Cork 6th August 1831 and arrived in Port Jackson on 2nd December 1831.
He kept a Medical Journal from 27 June to 14 December 1831 - The majority of the prisoners were found to be in poor health and several had been in the hospital until a few days before embarking. George Birnie considered some men were unfit for the voyage and should never have been sent on board. The prisoners on this vessel were well attended by Captain Ager and George Birnie........ The men were allowed on deck regularly and the prison was kept much cleaner than the barracks. Supplies of preserved meat, tea, sulphate of magnesia, castor oil and oil of turpentine (used orally or by enema for dysentery) were insufficient and so were replaced by Birnie at his own expense. Chloride of lime (for scurvy) was used liberally during the voyage and greatly contributed to the comfort of all on board. Captain Ager ordered milk and fresh bread to be given to the sick every day. He also had a place fitted up behind the fore chains on each side, for the people to retire to [as a toilet], to alleviate the nuisance throughout the ship caused by the soil pans.
George Birnie recommended similar arrangements should be generally adopted by order of the Navy Board. He also recommended the adoption of iron bars as less wasteful than the wooden prisons fitted in ships and taken down at the end of each voyage. Iron bars would also allow better circulation. Scurvy occurred only amongst the prisoners on this voyage. The surgeon attributed this to the 'regular supply of spirits supplied to the crew, guard and families, and their previous wholesome food as well as an absence of depressing passions.' 
Surgeon-Superintendent Caroline 1833
He was appointed to the female transport Caroline which departed Cork 15 April 1833 and arrived in Port Jackson 6th August 1833.
He kept a Medical Journal from 1 March to 28 August 1833 - George Birnie's Journal - The Convicts when embarked had in general a healthful and clean appearance and throughout the voyage they kept themselves and their berths in a state of the most perfect cleanliness. We had a good deal of sickness and incidental during a long and solitary voyage to persons unaccustomed to a sea life; but no deaths or casualties among the free settlers, the prisoners or any of their children. It will be seen by the copy of the daily sick book, I had in all ninety seven cases on the list and I regret that I can give only sixteen and they imperfect, my papers having gone astray during the disembarkation of prisoners. These few cases however will give a pretty correct idea of the nature of the complaints which generally occurred during the voyage.
By my instructions from the Admiralty, I am desired to guard as far as possible against the introduction and spread of contagions as well as attend to the health, comfort and morals of the prisoners placed under my charge and I assert that nothing is more calculated to fulfil the intention of these instructions than the the substitution of proper water closets for the disgusting and beastly soil pans especially in female convict ships to all consideration of the intolerable nuisance produced in cases of general sickness by these soil cases not only in the prison and hospital but all over the ship, the men particularly in bad weather, are brought more in contact with the women than they would otherwise be and the disgusting office makes them assume liberties which they would not otherwise do - Various other considerations, obvious enough but not fit to be stated here induce me again to repeat that every convict ship and more especially female convict ships should always be fitted up with water closets. No one who has not actually experienced it can form any adequate idea of the abominable and disgusting nuisance of these soil pans as they are delicately called. The chloride of lime was liberally used and contributed greatly to the sweetness and comfort of the prison, hospital and place allotted to the free settlers.
Surgeon-Superintendent Layton and Blenheim
George Binie was also employed on the Layton to Van Diemen's Land in 1835. His Medical Journal dated from 13 August to 16 December 1835. on this voyage.
His last appointment as surgeon superintendent of a convict ship was to the Blenheim which departed Woolwich 15 March 1837 and arrived in Van Diemen's Land 16 July 1837.
George Birnie Held in High Regard
The prisoners on the above ships were fortunate in that George Birnie was appointed as surgeon on these vessels. He was not only well experienced but kind hearted and caring towards his patients -
'The Medico Chirugical Quarterly Review for January 1840 contains a paper by Dr. Fergusson of Windsor on the subject of yellow fever; he is at the time discussing the question of contagion:
'In the year 1816, while yellow fever was raging at Barbadoes, it was my lot, I suppose from being an old seasoned subject, to be taken with very violent but irregular intermittent fever. Admiral Harvey invited me to go on a cruise with him among the islands in the flag ship; and, soon after leaving Carlisle Bay, yellow fever broke out among the crew. There were, if I recollect right, seven very bad cases; but Mr. Neale the surgeon a very sensible and excellent officer, at once negatived the smallest idea of contagion. The assistant-surgeon, Mr. Byrne* brought up his cot from the cock pit and slung it in the sick bay, in order that at all hours he might be near his patients. Their comrades were allowed the freest access, and the officers of the ship were encouraged to visit and show them every attention. The consequences were the happiest, for, although the cruise lasted several weeks, we did not carry back a single case of the disease to Barbadoes.
*Note. I write from memory and trust that I do not mistake his name, for his conduct was beautiful. I know no better term to express this tribute of my respect and, if in life, I hope he will accept it. I believe he afterwards sailed with Captain Basil Hall as surgeon of the frigate he commanded:
Those who have the pleasure of being acquainted with our fellow townsman, George Birnie Esq., will be at no loss to recognise him in the foregoing portrait; and it is in no small degree gratifying, among the conflicts of daily life, to find so just and pleasing a remembrance of one brother by another in the same arduous and harassing profession. Long may that gentleman live to be so appreciated by those who surround him, and remembered by the friends from whom he has been separated by time.'...The Belfast News 4th February 1840.
George Birnie was on the List of Surgeons of the Royal Navy who were fit for service in 1841. He was listed in the 1843 Belfast Street Directory residing at 21 York Street, Belfast.
He died at his residence 8th October 1845 aged 52 years and was buried at Rashee Old Graveyard, Co. Antrim. After George Birnie's death his widow Isabella nee Beggs lived on at York Street for more than 30 years until her death in 1878. 
 Journal of George Birnie on the voyage of the Asia in 1831. Ancestry.com. The National Archives. Kew, Richmond, Surrey.
 Journal of George Birnie on the voyage of the Caroline in 1833. Ancestry.com. The National Archives. Kew, Richmond, Surrey.