This paper intends to deal with technology transfer to the Ottoman Empire, and its possible relation to the concept of “the useful knowledge” (ulum-u nafia), which was important in various classifications of the sciences proposed by Muslim scholars in the premodern period. By focusing primarily on Ebu Sehl Numan Efendi, an Ottoman scholar in the eighteenth century, and his work entitled Tedbirat-i Pesendide which is a military recommendation-diary, I will question the way in which the Ottomans internalized new sets of knowledge appropriated from Europe, particularly engineering-oriented knowledge, by applying to the idea of the “useful knowledge.” Numan Efendi was a madrasa scholar who appointed a variety of important judicial positions throughout his career. He was not only well-educated in theoretical and madrasa-oriented sciences, but also remarkably talented in practical sciences such that when he was a border imam among the group that represented the Ottoman Empire in designating new borders of the states after the war between the Ottoman, Habsburg and Russian states, as he reports in his book, he could make the instrument used by the Habsburg by himself. Interestingly enough, Ebu Sehl Numan Efendi frequently refers to the concept of the useful knowledge in his diary, Tedbirat-i Pesendide, when he feels himself compelled to legitimize what he wants to appropriate from European practical knowledge, claiming that this knowledge already belongs to him. I will argue that Ebu Sehl Numan Efendi’s self-confidence in appropriating knowledge stems from the complex relationship between the practical knowledge and the traditional religious sciences, particularly, fiqh (jurisprudence) and kalam (Islamic theology). The main questions of my paper will be as follows: What was the positive/negative impacts of the concept of the useful knowledge on transferring technology? Can one can claim that scientific knowledge have global or local belonging according to the classical Islamic-Ottoman understanding? How Ebu Sehl Numan Efendi legitimize while he was transferring European technology? And finally, what are the main contributions of Ebu Sehl Numan Efendi to Ottoman Military Engineering?