The Rev. Dr Nevil Maskelyne was the fifth English Astronomer Royal, an office he held for over forty years. As a young man, the eclipse of 25 July 1748 ignited an interest in astronomy and Maskelyne went on to study mathematics at St Catherine's College, Cambridge. He was ordained as a minister in 1755 and became a fellow of Trinity College, Cambridge the following year. In 1758 he was admited to the Royal Society and set about developing a method of determing longitude using the position of the moon. The overall aim was to accurately calculate the Earth's distance from the sun thus establishing a better understanding of the scale of the solar system. Maskelyne was appointed Astronomer Royal in 1765 and his primary task was to observe the moon and his findings were published through the Royal Society. He was elected to the council of the Royal Society in 1766 and conducted various experiments on its behalf, including one to measure the earth's density for which he won the society's highest award, the Copley medal, in 1774.
Maskelyne married Sophia Rose (1752-1821) of Cotterstock, Northamptonshire, in around 1765 and they had a daughter, Margaret (1786-1858). The portrait miniature worn by Sophia Rose is identical to the one of her husband in the present lot.
For further information about the life and work of The Rev. Dr Nevil Maskelyne, see D. Howse, Oxford Dictionary of National Biography, online version, 2009.