Summary
The use of mathematical and astronomical instruments played an important part in the development of Jonas Moore's career. Though debates about the nature of mathematics raised questions about the value of instruments, they remained essential to his work as a teacher, as Surveyor of the Fens and as Surveyor-General of the Ordnance. His confidence in them was most fully expressed in his equipping of the Royal Observatory and in his textbook for Christ's Hospital Mathematical School. His belief in the inseparability of mathematical practice from theory meant that, for him, instruments continued to offer a means of putting certain knowledge into practical effect.