- A SKEPTIC's GUIDE - A SKEPTIC's GUIDE 
Ever the Modern Physicist, Galileo recognized clearly that the big money and prestige were in military applications of science. In those days the new weapons technology was cannons and how to aim them more accurately at targets. His contributions to this art took two main forms: the first was his invention of the magnifying telescope, with which it was possible to identify targets at great range and assess the damage done to them by one's cannonballs. To be fair, I should point out that this invention was warmly received by seafarers and astronomers as well as generals; in fact, with it Galileo himself made famous and wonderful observations of the Moon, the "Galilean" moons (named after guess whom) of Jupiter and numerous other objects in our Solar System, thereby initiating the modern pastime of Planetology that recently culminated in the fantastic close-up views of the outer planets and their satellites by Terran space probes. One can easily imagine how ridiculous the Church's Ptolemaic ergocentric model of the Heavens must have seemed to Galileo after watching so many other planets execute their orbits as clearly visible globes lit on the Sun side.6.7 There are two sides to every coin.
Galileo's second contribution to the art of artilliery was his formal explication of the behaviour of falling bodies, of which cannon and musket balls were oft-mentioned examples. Galileo "showed"6.8 that the velocity of a falling body increases by equal increments in equal times (in the absence of friction), which is the definition of a state of constant acceleration.