Jones, Lady Katherine (1615–91), Viscountess Ranelagh , woman of letters, was born 22 March 1615 in Youghal, Co. Cork, fifth daughter in a family of fifteen children of Richard Boyle (qv), 1st earl of Cork, and Catherine (qv), daughter of Sir Geoffrey Fenton (qv). In Dublin, she married (4 April 1630) Arthur Jones (qv) (d. 1670), son of Roger Jones (qv), 1st Viscount Ranelagh. They had four surviving children: Catherine (1633–75), Elizabeth (b. 1635), Frances (1639–1672), and Richard (qv), the future 1st earl of Ranelagh. In 1638 Katherine and Arthur joined her father in England, where they remained for approximately two years, returning to Ireland just before the 1641 rising. Trapped in Athlone castle for nearly two years, Katherine was unable to leave Ireland with her children until 1643, when she established her London household in St James Square. By the 1650s the Ranelagh marriage had deteriorated to the point that Lady Ranelagh actively sought a legal separation from her husband. While he spent most of his time in Ireland, Lady Ranelagh stayed mainly in England; however, in the 1650s she made an extended trip to Ireland. Her letters indicate that other trips to Ireland may have been made in the 1660s and perhaps in the 1670s after her husband's death.
Her London house became a meeting-place for political and religious activists, as well as writers and scientists, including her youngest brother, the Hon. Robert Boyle (qv), and many of the individuals whom he met at his sister's home would become his lifelong professional and social associates. Within Lady Ranelagh's household were numerous members of the Boyle extended family, including her nephew Lord Barrymore, for whom she employed John Milton as tutor. Describing Lady Ranelagh as an exceptional woman in his letters, Milton was also to be her son's tutor in 1653. From the 1640s until her death, Lady Ranelagh interacted with many of the leading figures of her age, and her letters reveal a lifelong interest in the affairs of Ireland and England. Her philosophic and scientific correspondents included many of the founding members of the Royal Society, while her religious circles included, among others, Bishop Gilbert Burnet, William Robertson, and John Dury. She maintained extremely close relationships with her brothers, all of whom appeared to defer to her opinion at one time or another. Her influence over them was well known to their contemporaries, with the 1st duke of Ormond (qv) observing that Lady Ranelagh governed the Boyle men absolutely. She had a close friendship with her youngest sister, the diarist Mary Rich (qv), countess of Warwick, and with her sisters-in-law, the countesses of Cork and Orrery. Beyond her immediate family circle, Ranelagh was esteemed by women such as the duchess of Ormond (qv) and the duchess of Hamilton, the female members of the family of the 1st earl of Clarendon, and Lady Rachel Russell.
For the last thirty years of their lives, the unmarried Robert Boyle lived in Lady Ranelagh's London home, where she had a laboratory constructed in the rear garden. She died on 23 December 1691 and Robert died eight days later. In his funeral oration for Robert Boyle, Bishop Burnet also commemorated the sister when he stated that Lady Ranelagh had been an ‘intercessor for all persons of merit’, and having ‘lived the longest on the most public scene’ she was ‘the greatest figure in all the revolutions of these kingdoms for about fifty years’. Burnet concluded that ‘such a sister became such a brother’ (Gilbert Burnet, A sermon). The bishop would have been as accurate to have asserted that such a brother became such a sister.
Frequently, the letters of Lady Ranelagh were circulated among her correspondents. The circulation indicates that she participated in several coteries, one of which centred on the new philosophic inquiries while another consisted of individuals with shared religious and political concerns, some of whom had common interests in Ireland and the New England colonies. Her interest in the arts was reflected in her relations with John Milton, Andrew Marvell, Wentworth Dillon (qv), Edmund Waller, and Anne Wharton. Her letters are an insightful record of a woman who flourished in the highest intellectual, political, and social circles in Ireland and England, and was able to establish her own autonomous space within these spheres.