Watson married Elizabeth Galsworthy not long after arriving in Victoria, who died several years afterwards in England.

[2] Watson almost immediately joined George Christian Darbyshire, Engineer of Construction, then District Surveyor at Williamstown.

His first work was to lay out the main road from Melbourne to Ballarat, with instructions to examine the country with a view to possible future railway construction.

The datum was an assumed low-water mark in Hobson's Bay, and the levels for the whole railway system of the colony were reduced to it.

Having satisfactory carried out these works, he was granted twelve months' leave of absence on account of ill health, and visited Europe, accompanied by his wife, who died in England.

In 1878, a political crisis let to the Government dismissing the Engineer in Chief Thomas Higinbotham along with 137 other public services in what became known as "Black Wednesday" – 8 January 1878.

Watson instead took on a challenging expedition for the Queensland Government to explore the country from the East Coast to the Gulf of Carpentaria, with a view to the construction of a railway.