Galileo is justly famous for his revolutionary scientific theories, such as his concept of motion, a crucial element in confirming the Copernican structure of the universe. But he also reached a level of excellence in designing and making innovative instruments, such as the geometric and military compass, a compact device used to perform an amazing number of operations for both civil and military purposes; and the thermoscope, the first step in the development of the modern thermometer. He strove also to understand the nature and effects of magnetic attraction, as shown by his theoretical studies and experimentation with magnets.