Catherine Barton (1679–1739) was an English woman who oversaw the running of the household of her uncle, scientist Isaac Newton.

[3] Her uncle was also fond of her; an excerpt of an uncharacteristically warm letter from Newton survives, regarding her contraction of smallpox: "Pray let me know by your next how your face is and if your fevour be going.

[6] Voltaire also insinuated that Newton's preferment to the Royal Mint was the result of Barton's alleged affair with Charles Montagu.

Montagu wrote that these bequests were "as a token of the sincere love, affection and esteem, I have long had for her person, and as a small recompense for the pleasure and happiness I have had in her conversation".

Halifax's official life defended Barton against accusations that she might have been sexually involved with him, stating:as this Lady was young, beautiful and gay, so those that were given to censure, pass'd a Judgment upon her which she no Ways merited, since she was a Woman of strict Honour and Virtue; and tho' she might be agreeable to his Lordship in every Particular, that noble Peer's Complaisance to her, proceeded wholly from the great Esteem he had for her Wit and most exquisite Understanding.

[2]Based on the generosity of the bequest, astronomer John Flamsteed wrote, apparently sarcastically and spitefully, that Barton must have "excellent conversation".

[citation needed] On 9 July 1717 she became engaged to marry John Conduitt who had arrived in England a few weeks earlier in May of that year.