Complex sentence: The core drill was developed in ancient Egypt by 3000 BC. The pump drill was invented during Roman times, it consists of a vertical spindle aligned by a piece of horizontal wood and a flywheel to maintain accuracy and momentum.
Split into simpler sentences: The core drill was developed in ancient Egypt by 3000 BC. The pump drill was invented during Roman times. It consists of a vertical spindle aligned by a piece of horizontal wood and a flywheel to maintain accuracy and momentum.