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.
It spans the 30-60th degree of the zodiac, between 27.25 and 54.75 degree of celestial longitude. Under the tropic zodiac, the Sun transits this area on average between April 20 and May 20 each year. Under the sidereal zodiac, the sun transits the constellation of Taurus from May 16 (approx.) to June 21.