http://www.certifiedchinesetranslation.com/10/0102-Isaac-Newton.html

From the article, which includes the math to explain Newton's apocalyptic reckoning:

Sir Isaac Newton (1642 – 1727) is a noted English scientist and mathematician known for his contributions to the discovery of gravity from the falling apples. What is little known about him is the many works he wrote that would now be classified as occult studies such as Biblical interpretation (especially of the Apocalypse).

To understand the reasoning behind the 2060 prediction, an understanding of Newton's theological beliefs should be taken into account, particularly his apparent antitrinitarian beliefs and his religious views on the Papacy. Both of these lay essential to his calculations, which ultimately would provide the A.D. 2060 time frame.