Brevoort was the aunt of W. A. B. Coolidge, whom she brought to Europe in 1865, when he was 15 years of age, and introduced to alpine climbing. Coolidge eventually became an outstanding mountaineer, with over 1,700 ascents in the Alps, and the greatest alpine historian of the Victorian age. The two climbed together for over ten seasons, and were joined in many of their adventures by Tschingel (1865-1879), a small dog their guide Christian Almer gave to her nephew. Later, she would proudly refer to their canine companion as the only Honorary Lady member of the Alpine Club. She and Coolidge journeyed to the Dauphiné several times in order to attempt the Meije, but encountered bad weather each trip. In 1876, she had her final opportunity for a first ascent, but, instead, stayed in the Oberland in order to give more money to her nephew, to support his efforts in the range.