Though James Lind MD, FRS (1736-1812) has long been a feature of Shelleyan biography, references to him have been superficial, and subject to often repeated inaccuracies. Frequently dismissed as an eccentric or passed over altogether, Lind has become a purely biographical figure, associated only with a brief episode in the poet's childhood. Despite Shelley's own assertion that he owed more to Lind than to his own father, generations of critics have largely ignored the possibility of any influence by him on Shelley's creative work. Lind was, in fact, an extremely accomplished practitioner in every field of natural philosophy that interested Shelley, and that was later to infuse his poetry with its unique scientific metaphorical imagery. These subjects included medicine, astronomy, chemistry, geology, and meteorology. Though an obscure figure himself, Lind was a friend or correspondent of many of the greatest figures of the Enlightenment, such as Benjamin Franklin, William Herschel, David Hume, James Watt, and many others. Drawing upon original archival and historical research, Lind is proposed as a new influence on Shelleyan passages whose scientific character may already have been recognised, but with Lind now providing a more likely origin or more direct link for influences thus far attributed to other conjectural sources. Lind is also introduced as a potential source for certain segments of the poet's work whose possible significance has hitherto gone entirely unrecognised. This thesis aims to raise the profile of James Lind as an influence on Percy Shelley's work, and also to contribute new material to our understanding of Shelley's scientific thought. Comparisons are also made with existing scientific commentary on Shelley's work. In pursuit of these aims, this thesis is necessarily themed with reference to the scientific subjects under discussion, rather than chronologically, or textually.