Gardner was a keen horseman and he travelled extensively over the district and compiled the first detailed map of northern New South Wales.
[2] Gardner's map reveals competent draughtsmanship and detailed attention to roads, tracks and pastoral properties.
By 1848 he was back in Australia where he wrote and published, The cultivation of the cotton plant in New South Wales (1848 & 1850).
He also published, An enquiry into the effect produced by the deluge upon alluvial deposits of gold in Australia (1856).
These are now held by the Mitchell Library in Sydney and are a historical resource for the early settlement of northern New South Wales.