Grand Canal
The formation of canals was scarcely known in Ireland until the year 1765, when the Grand Canal was begun by a company of enterprising men, who were incorporated in 1772 by an act of parliament; boats began to ply to Sallins in 1783, to Athy in 1791; it is a cheap and pleasant mode of travelling, at the rate of 3½ miles an hour. This Canal is carrying on to Philipstown, Banagher, and Birr. From the first lock at Kilmainham, a cut has been made to the river Liffey at Rings-end, extending 3 miles, having 12 neat bridges to accommodate the different roads to Dublin. At the seventh lock on this line, the great basons and docks are, 4000 feet long, and 330 feet average breadth, capable of containing 400 sail of square-rigged vessels. On the 23rd of April 1796, it was opened at high tide; when his excellency Earl Camden in the Dorset yacht, commanded by Sir A. Schomberg, with a number of barges from the canal, cutters, and boats highly decorated, were admitted under a discharge of 21 pieces of cannon, and had room to sail in various directions. There were 60,000 people present; it was the best aquatic fête ever seen in this kingdom. John Macartney Esq addressed his Excellency, and was knighted.
Royal Canal
The Royal Canal is another proof of national spirit and national industry. The subscribers were incorporated in 1789; it is now finished beyond Kilcock, 14 miles, and is proceeding rapidly to Kinnegad. On Sunday the 20th of December 1795, the first excursion was made in a barge to Kilcock, with the Duke of Leinster and Marquis of Kildare, amidst the acclamations of the people.
J S Dodd, MD The Traveller’s Director through Ireland; being a topographical description not only of all the roads but of the several cities, towns, villages, parishes, cathedrals, churches, abbeys, castles, rivers, lakes, mountains, harbours, the seats of noblemen and gentlemen on those roads: their antiquities and present state respecting parliamentary representation, patronage, trade, manufactures. commerce, markets, fairs, distances from each other, and natural curiosities; with an account of their foundations, vicissitudes, battles, sieges, and other remarkable events that have occurred at them — insomuch, that this work comprehends in itself, an accurate Irish itinerary, an extensive Irish gazetteer, an Irish chronological remebrancer [sic], and an epitome of the ecclesiastical, civil, military and natural history of Ireland, from the earliest accounts to the present year, and every information necessary for the resident, or the stranger. Embellished with two elegant maps; one of the roads and post towns in Ireland, the other of the city of Dublin, compiled from the most authentic authorities Dublin 1801
Irish waterways history 
I am a decendant of John Macartney, living in Australia, I am keen to learn more of his involvement in the development of the Irish waterways
Ruth Delany, in The Grand Canal of Ireland [David & Charles, Newton Abbot 1973], mentions Sir John Macartney in several places.
On page 56, she says that John macartney, who had joined the board of the Grand Canal Company in 1783 and was a considerable shareholder, wanted the company to work on the Circular Line connection to the Liffey in Dublin at the same time as working on the Barrow and Shannon lines. On page 58, she says that John Macartney, now chairman of the company, was “knighted on the spot” by the Lord Lieutenant at the opening of the Grand Canal Docks, at the junction between Circular Line and Liffey in Dublin, on 23 April 1796.
On page 63 she says that for thirty years, until 1810,
One of the cargoes carried on the canal was horse-dung: the traffic both removed it from the city and provided manure for farmers in areas along the canal.
On the same page she mentions an Arthur Chichester Macartney as an active member of the board in the early nineteenth century; she does not say whether he was related to Sir John.
On page 76 she says that, by February 1910, Sir John macartney “had already withdrawn from an active role in the company’s affairs” and that, in the same month, shareholders ejected other directors including A C Macartney.
Finally, on page 143 she says that John Macartney and Richard Griffith “decided that the best method of building up a trade in coal on the canal was for the company to acquire a colliery”; you can read about the colliery here.
The Macartney Aqueduct on the Grand Canal is here.
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