From age 12 to age 17, Newton resided with William Clarke, apothecary, in Grantham, where he acquired his interest in chemistry. While living with the Clarke family, Newton was educated at The King's School, Grantham (where his signature can still be seen upon a library window sill). He spent much of his time on independent pursuits, and did poorly in school. He was removed from school, and by October 1659 he was to be found at Woolsthorpe-by-Colsterworth, where his mother, widowed by now for a second time, attempted to make a farmer of him. He hated farming. Henry Stokes, master at the King's School, persuaded his mother to send him back to school so that he might complete his education. This he did at the age of eighteen, achieving an admirable final report.