File:Samuel Molyneux and the Astronomers of Castle Dillon Armagh.docx

Summary.

William and Samuel Molyneux: The Astronomers of Castle Dillon Armagh.  By J.A. Finnegan.

This paper describes the distinguished lives and accomplishments of William Molyneux FRS and those of his son, Samuel Molyneux FRS: Courtier, Politician, Astronomer and telescope maker.

With substantial estates in Ireland, Samuel Molyneux (1689–1728) came from a wealthy background. Graduating from Trinity College Dublin, he spent the years 1710-1712 on the improvement of the estate at Armagh, utilising a library and Observatory at Castle Dillon created by his late father William Molyneux FRS (1656-1698) The distinguished polymath and Member of Parliament for Trinity College Dublin. In 1697 William offered to underwrite the second edition of the Philosophiae Naturalis Principia Mathematica for Isaac Newton and has been called “perhaps the single most important figure in the history of Irish Science” (Section 1.2).

Visiting London, on 1^st December 1712 and proposed by Newton, Samuel Molyneux was elected Fellow of The Royal Society and “receiv`d by…men of distinguish`d character”. He continued to reinforce and progress his family`s connections at Court and with the most influential intellectual and political figures of this era; as vividly described in his letters to his uncle, Dr. Thomas Molyneux FRS (1661-1733) (Section 2). Subsequently, in 1714 King George I appointed Samuel Molyneux Principal Secretary to his son Georg August, the new Prince of Wales (Section 3).

In 1721, “[Samuel] Molyneux has a mind to purchase the Mural Arc, and the quadrant that used to stand in the great room” at Greenwich Observatory (Section 4.1). In 1725, using Samuel`s private observatory at Kew House London, Samuel Molyneux and Rev. James Bradley FRS (1692-1762) commenced precise positional measurements of Gamma Draconis, initiating what have been called “the great discoveries, the Aberration of Light and the Nutation of the Earth’s Axis”. Bradley wrote, “But if it [Molyneux`s “Parallax instrument”]  had not greatly exceeded the Doctor's [Hooke] in Exactness, we might yet have remained in great Uncertainty as to the Parallax [distance] of the fixt Stars” (Sections 4-7). In 1727, Samuel`s invitation to Dr. Robert Smith FRS (1689-1768) Plumian professor of astronomy at Cambridge, to become resident at his observatory at Kew, suggests Samuel’s intention of continuing observations using complementary parallax instruments (Sec. 6).

The circumstances and consequences of Samuel`s bizarre death in 1728 at the age of just 38, which prevented his plans being implemented, are detailed (Section 8-9). Samuel Molyneux was an authority on the casting of “Metalline Specula” (Section 4.0). Listed in the posthumous 1730 Kew House Observatory auction catalogue (Section 9) “A large Concave Metalline Speculum, 26 Inches Diameter, fitted with proper Apparatus to set it in different Positions, made by Mr Molyneux" appears to describe what would have been the world’s largest telescope (Section 10).