George Armstrong was also the author of Essay on the Diseases Most Fatal to Infants, first published in 1767. This was one of the world's first textbooks on children's diseases.
Pictures are from P. M. Dunn's excellent article "George Armstrong MD (1719–1789) and his Dispensary for the Infant Poor," Archives of Disease in Childhood Fetal and Neonatal Edition 2002;87:F228.