Motion and Time of Class 7
There is archaeological evidence of oil lamps about 4,000 BCE, and the Chinese were using oil for heating and lighting by 2,000 BC. Oil lamps are still important in religious practices. The shape of the lamp gradually evolved into the typical pottery style shown. It was possible to devise a way of measuring the level in the oil reservoir to measure the passing of time.
NCERT SOLUTION FOR CLASS-7 SCIENCE (Science for grade-7 NCERT solutions)