The Stewart family owned some of the land south of Gladstone Avenue, which was then the southern limit for the city of Ottawa.

The area was called Stewarton, and the family home was located on the current site of the Canadian Museum of Nature.

In 1881, with William Hodgson, he built the Molson's Bank building on the Sparks Street Mall.

In 1897, he visited London, seeking financial backers for The Montreal, Ottawa and Georgian Bay Canal Company, a company created by an Act of the Canadian Parliament in 1894 and empowered to construct a canal linking the Ottawa River and Georgian Bay.

[2] A second visit to Britain in 1899 was more successful, securing support for the project from a syndicate managed by James Aratoon Malcolm and chaired by Sir Edward Thornton.