This subseries contains the papers of Elizabeth Livermore Hubbard Blake, primarily letters to Elizabeth from family and friends, and occasionally to Francis Blake, as well. Many letters, primarily those from the Hubbard, Dyer, Tudor, and Payson branches of the family, address Elizabeth as "Aunt Lise." Letters from Elizabeth's brother-in-law Ferdinand Canda relate to the health of her sister, Louise (Louisa) Jackson Canda.

This subseries contains the papers of inventor Francis Blake (1850-1913), primarily financial papers related to purchases and philanthropy, as well as Blake's time as a selectman for the town of Weston, Massachusetts. Also included are materials related to his memberships in various clubs and associations, a notebook of lens and shutter specifications, and scientific publications. Companies corresponded with include Zeiss lenses.

This subseries contains the papers of Agnes Blake (1876-1964), daughter of Francis and Elizabeth, who married Stephen Salisbury Fitzgerald. The papers are primarily correspondence, writings, and sketches from her adolescence and early school years.

This subseries contains papers related to George Ripley, a Blake cousin facing business and personal hardship who was assisted monetarily by Francis Blake. Some of the letters are written by George Ripley and reflect a hand injury. The remainder of the correspondence is between Francis Blake and Pinkerton's Detective Agency, which Blake employed at one point to locate his cousin, and between Blake and one of his legal and financial advisers about the anonymous allowance dispensed to his cousin. The financial correspondence includes a couple of letters with Elizabeth Blake after her husband's death.

Benjamin Sewall Blake, Sr.'s papers include both family and financial correspondence and a large amount of material related to his alumni activities as part of Harvard University's Class of 1901. The series also contains materials related to his military service, his time as Tree Warden for the town of Weston, and his memberships in clubs and societies, including the Laurel Brook Club, the Massachusetts Horticultural Society, and the Santee Club. Additionally, there are materials related to the Arnold Arboretum and associated land lawsuits, as well as two of Blake's lab notebooks. Two handwritten notes from Benjamin and Ruth's daughter Joan Blake (1928-1964) to her father are also included in his papers.

The papers of Ruth A. Field Blake consist chiefly of letters from Henry Poor and Benjamin Blake, as well as a travel diary kept on a trip to England in 1960.

Family correspondence is primarily between Francis and his family while he was away at school in his youth, as well as social correspondence and invitations through his college years and engagement to Caroline. A small group of letters, written by Caroline, documents their relationship from their engagement in 1936, through Francis's World War II service and deployment, and up to the 1950s and Caroline's travels abroad with two of their five children.

The papers of Francis Blake, Jr. (1909-1982) include materials related to Francis's travels in Europe in the 1930s and his Harvard law school admission and re-admission, as well as business correspondence. A baby book from 1909 is also included.

This diary was kept by Caroline Amory Hunnewell Blake (1915-2017) during a trip to Europe from 31 July to 16 October 1935 and a trip down the East Coast of the United States in October 1938. The leather-bound volume contains her trip to Europe and some of her trip in the United States, while a notebook insert in a separate folder contains a rewrite and continuation of the second trip.

Traveling with two friends, both named Jane, and her cousins Lillian and Theodore, she visits many destinations in France, Spain, Italy, Switzerland, and Germany. Entries record her impressions of the landscapes, historical sites, and peoples of the countries she visits, travel accommodations and food, and various activities such as driving, shopping, swimming, biking, and going to the movies. An extended stay in Paris towards the end of the trip includes sightseeing and shopping. Blake also discusses politics and current events, such as the League of Nations, attending a talk on opium, the assassination of Huey Long, the impending invasion of Ethiopia by Italy, and the rise of Adolf Hitler in Germany, including observing Hitler Youth and Nazi flags and speaking with a local hotel manager about the German middle class. While away, she corresponds with friends and family back home, including her eventual husband Frank (Francis Blake, Jr.).

Her entries for her 1938 trip, taken with her husband Frank, mostly include her observations of the landscapes they traveled through; cities and towns visited, including Williamsburg, Virginia; hotels and accommodations; and interactions with strangers and friends. In New England, she notes flood damage from the 1938 New England hurricane, and in the South the growing of cotton and tobacco and a visit to the Lucky Strike cigarette factory. In White Sulphur Springs, West Virginia, she mentions that her husband Frank drank both "White & Black" spring water. A fragment of correspondence has been removed from this booklet and placed behind it in the same folder.