 A while later, in his 1600 manuscript version of Le Meccaniche (On Mechanics), Galileo introduced the concept of momento, a quasi force that applies to a body at a moment, and which is somehow proportional to weight or specific gravity (Galluzzi 1979). Still, he had no good way to measure or compare specific gravities of bodies of different kinds, and his notebooks during this early seventeenth-century period reflect his trying again and again to find a way to bring all matter under a single proportional measuring scale. He tried to study acceleration along an inclined plane and to find a way to think of what changes acceleration brings to momento. Yet the details and categories of how to properly treat weight and movement eluded him.