The story of Jonathan Hulls and his scientific work is, for various reasons, of peculiar interest. Although mention of him is to be found in many works dealing with the steam-engine and, in some instances, he is referred to as the inventor of the steam-boat, it is a fact that very little is known concerning the man and his work. From time to time articles dealing with his invention appear in newspapers and journals, sometimes accompanied by drawings which are intended to represent the steam-boat. The authors of these articles usually appear to have given free rein to their imagination, with the result that readers are misinformed. Errors of this sort are not confined to non-scientific literature, and various conflicting statements are to be found spread throughout the body of engineering text-books. The object of this paper is to set out briefly such facts as are known concerning Hulls; to consider the scientific literature to which he had access, and to show how this may have influenced him.