To his contemporaries, what did Sir Isaac Newton seem to reveal the universe to be?

A designed, mechanical system - - like a constantly functioning clock.

Explanation:

Newton explained the universe and its functioning in his landmark work, Mathematical Principles of Natural Philosophy (1687). He pulled together the work of other key figures of the Scientific Revolution. His organized theory of universal gravitation gave the impression of the universe as a mathematical system that functioned like clockwork. Newton and others of the Scientific Revolution saw God behind the design of this system, as the "great watchmaker" who designed the universe as a perpetual watch or clock that could run on perpetually in predictable fashion.