In 1818 Charles Throsby, Hamilton Hume, James Meehan and William Kearns set out to find the route, a task accomplished that same year by Throsby and Kearns. The 1820s saw further exploration in the Canberra area associated with the construction of a road from Sydney to the Goulburn plains, supervised by Throsby and his overseer, Joseph Wild. While working on the project, Throsby learned of a nearby lake and river from the local Aborigines, and he accordingly sent Wild to lead a small party to investigate the site. On 1820, Wild ventured off from his two companions, and later that day arrived at the north shore of what is now known as Lake George. In Governor Macquarie visited the site, and while he was in attendance Throsby decided to push on to reach the river of which he had been informed. Accompanied by Wild and James Vaughan, he journeyed south in search of the Murrumbidgee. The search was unsuccessful, but they did discover the Yass River, and it is surmised that they would have set foot on part of the future ACT. A second expedition was mounted shortly thereafter, and Throsby's nephew Charles Throsby Smith, Wild and Vaughan further explored the Molonglo (Ngambri) and Queanbeyan (Jullergung) Rivers, becoming the first Europeans to camp at the site. However, they failed to find the Murrumbidgee, and Smith declared that the river did not exist. The issue of the Murrumbidgee was solved in 1821, when Charles Throsby mounted a third expedition and successfully reached the watercourse, on the way providing the first detailed account of the land where Canberra now resides. The next significant expedition to the region came in 1823, when Wild was employed by Brigade Major John Ovens and Captain Mark Currie to guide them to the Murrumbidgee. They travelled south along the river and named the area now known as Tuggeranong "Isabella's Plain", after Isabella Maria Brisbane (1821–1849), the two-year-old daughter of Thomas Brisbane, the then Governor of New South Wales. Unable to cross the river near the current site of Tharwa, they continued on to the Monaro Plains. The last expedition in the region prior to settlement was undertaken by Allan Cunningham in 1824. He reported that the region was suitable for grazing, and the settlement of the Limestone Plains followed immediately thereafter.