Rivers were used to turn watermills and the Romans even used geothermal water for heating. Until the middle of the 18th century renewable sources of energy were the only forms of energy available, but then, with the advent of the Industrial Revolution, fossil fuels began to be exploited.
The Sidereal Zodiac is the position of the sun referenced against the star background, as a measure of the flow of time. The framework for the star background is the constellations the sun passes in front of. This is the one astronomers use.
The Zodiac. The Secrets of the Signs. The Zodiac (Circle of Animals) is the name given to the band encircling the earth on either side of the ecliptic, the Sun's path. It is like a belt in space, about 15-18 degrees wide, across which the planets move and form their aspects, or geometrical relationships.