Ernest Rutherford, who guided her graduate work, regarded her as comparable to Marie Curie in the calibre of her aptitude.

In 1899, even before her thesis was completed, her work on damping of electrical oscillations was published in the Transactions of the Canadian Section of the Royal Society.

[4] Rutherford arranged for Brooks to take this fellowship at his former lab at the University of Cambridge, where she became the first woman to study at the Cavendish Laboratory.

[8] In 1903, Brooks returned to her position at Royal Victoria College and rejoined Rutherford's group, carrying out research that was published in 1904.

When in 1906, she became engaged to a Columbia University physics professor, Dean Laura Gil of Barnard responded by saying "that whenever your marriage does take place it ought to end your official relationship with the college".

This began a heated exchange of letters, in which Brooks conveyed that she felt she had a duty to both her profession and her sex to continue her work even after marriage.

[3] In the summer of 1906, Brooks moved to a retreat in the Adirondack Mountains run by John and Prestonia Martin, two prominent Fabian Socialists.

In the letter of recommendation Rutherford wrote for Brooks' application, he noted that "next to Mme Curie she is the most prominent woman physicist in the department of radioactivity.

Miss Brooks is an original and careful worker with good experimental powers and I am confident that if appointed she would do most excellent research work in Physics".

[8] Brooks died April 17, 1933, in Montreal at the age of 56 "of a ‘blood disorder’,"[11] presumably leukaemia caused by radiation exposure.

[14] In the 1980s, the importance of Harriet Brooks' contributions to physics became recognized as foundational work in the field of nuclear science.

[14][6] The fact that the new gas was significantly lighter than thorium led Rutherford and Frederick Soddy to propose that it must be a new chemical element, now known as radon.