The theory of the Ballance, scales, steel-yard &c. and all and the 3 species of lever’s continued to which (viz) the lever he referred allmost all the instruments in life, and universally. To make a aequilibrium, the product of the quantity of matter in the weight multiplyed into its distance from the Center of motion, must be equal to the quantity of matter in the power, multiplyed into it’s distance from said Center.