Captain Jules d'Urville arrived in Sydney Harbour on 2 December on the French corvette "L'Astrolabe". The "L'Astrolabe" was on a voyage of exploration, which gave Stirling an opportunity to assess French interest in the region. Stirling and d'Urville dined together several times and Stirling discovered that the "Astrolabe" had a detailed chart of the Swan River. Before leaving England, Stirling had studied the available charts of the west coast of Australia and had concluded that the Swan was a possible site for a harbour and settlement and had hoped to be the first European to explore and chart it. However, d'Urville indicated that the French did not consider that the Swan would be a suitable site for a harbour, because of the difficulty of access and lack of fresh water. This gave Stirling a free hand.