Little is known about Newton, an artist with a very common name and not many surviving examples of work. McKechnie is unable to differentiate between a Newton who worked 1818-1820, and a J Newton working 1838-40. Both apparently painted silhouettes from Dublin, though there is also some confusion about addresses.
Source: McKechnie (Author of, British Silhouette Artists and their Work 1760-1860)
Newton (McKechnie Section 2)Source: Joll (Hon. Secretary of the Silhouette Collectors Club and Editor of the Club's newsletter)
Newton (SCC Newsletter July 1997)