Letters of Euler on Different Subjects in

Let us start our panoramic overview of what is known in Natural Philosophy by setting the stage of discourse — the universe, its range of sizes and motions. Starting from a “foot”, we can go down to a ten thousandth of a foot, which is the size of the smallest ‘animal’ visible. Conversely we can go up in size to a mile, to the size of the Earth, the distance of the Moon, the Sun, and finally the farthest stars at possibly two hundred million billion feet distance. If we look at motion, we can go from a leisurely walk to running, to a galloping horse, the wind, sound, a cannon projectile, the Earth’s rotation is faster still, the Earth’s speed around the Sun, and finally the speed of light itself.