Born in New Jersey, Isham was educated at Cornell (1908-09) and Yale (1910-11) universities. In 1915 he enrolled in the British army, where he eventually joined the staffs of General Haig and Field Marshal Robertson and was bestowed the decoration of Commander of the British Empire.
He was an avid book collector and became almost obsessed with acquiring the Boswell papers. In the words of a Kirkus Review, Isham "over a period of 21 years sacrificed his home, his marriage, his fortune, and much of his cherished collection of books in order to complete the archives." Kirkus Reviews further describes him as "a curious kind of hero--a mild dilettantish fellow of unsociable nocturnal habits--but he pursues his love of Boswelliana so singlemindedly and with such resourcefulness, that his achievement takes on epic proportions." 1
On July 20th, 1949 Isham handed over the massive amount of Boswell papers which he had accumulated over a period of several decades, to Yale University at the university's Sterling Memorial Library. Almost half a century later, his close friend Mary Eccles Hyde, herself a collector who with her husband Donald accompanied Isham to Yale on that special day, wrote of his last years beautifully:
"Though Ralph lived for almost six years after this - and was rewarded by quiet happiness in a final marriage - his extravagant, lovable, dedicated, tempestuous life, so familiar to his friends, ended when he achieved his Great Cause, the Boswell papers safe at Yale."2
The Isham Memorial Library at Harvard University is named for Ralph Isham.3
Isham's great achievement was to acquire the bulk of the personal papers of James Boswell, a number of which he had edited and privately published in the 1930s, before selling them to Yale University in 1949. The story of him and his purchase of the papers from various sources is described in much detail in David Buchanan's "Treasure of Auchinleck" and Frederick Pottle's "Pride and Negligence".