Specifically, for the construction of what would become the South Bridge, for rebuilding or improving the University of Edinburgh, for enlarging the public markets, for lighting the said city, for providing an additional supply of water, for extending the royalty of the said city for levying an additional sum of money for statute labour in the middle district of the county of Edinburgh, to complete the Mound and to erect a bridge between the road to Leith and Calton Hill across Calton Street.

The first specific proposal for a South Bridge was produced on 6 September 1775 with the publication of a pamphlet setting out heads of a Bill.

The promoters were a Committee of Heritors of the Shire of Edinburgh, including Henry Dundas who acted as Chairman, and the Duke of Buccleuch.

Andrew Dalzell wrote to a friend in December: "It is now resolved to build a bridge across the Cowgate, passing between the College and the Infirmary.

This startling prospect gave rise to another pamphlet, published in early 1785 by James Gregory, Professor of the Theory of Medicine, in the form of "A letter to the Right Honourable Henry Dundas on the Proposed Improvements in the City of Edinburgh.