Lionel Henry Cust, Dictionary of National Biography… (1892)
“ He subsequently went to Rome, and remained there for fourteen years, two of which he spent under Nicolas Poussin, apparently engaged in landscape-painting. On leaving Rome he came to England, where he devoted himself to portrait-painting. His best-known portrait is that of Robert Boyle [q. v.] , of which there are versions at the National Portrait Gallery, the Royal Society, and Hampton Court ”
