Died: After 1972 in London, England

Gladys Mackenzie's father was Lachlan Paterson Mackenzie, an ironfounder, of Polwarth Terrace, Edinburgh. Her mother, Helen Macgregor Martin, was a teacher. Gladys attended Craigmount School, Edinburgh, from 1913 to 1919 and, in passing, we note a news item which tell us that in 1914 she took part in "a fancy dress frolic for children under twelve dressed as a Normandy Peasant." She sat the Scottish Leaving Certificate Examinations and obtained passes at Higher level in English, French, Latin, and Mathematics, having obtained a pass in Lower mathematics in the previous year.

In 1919 Mackenzie matriculated in the Faculty of Arts at the University of Edinburgh giving Church of Scotland as her Religious Denomination. She studies a wide range of courses. At Ordinary level: Mathematics (1^st and 2^nd Ordinary), Chemistry, Natural Philosophy, Philosophy. At Honours level: Natural Philosophy, Mathematics, Final Natural Philosophy, Final Mathematics, Calculus, General Analysis, Heat, Electricity I and II, General Physics, Higher Algebra and Geometry. She graduated M.A. on 17 July 1924 with First Class Honours in Mathematics and Natural Philosophy. She was also awarded a B.Sc.

Mackenzie was appointed as an Assistant in the Department of Natural Philosophy in the University of Edinburgh. She worked with Charles Glover Barkla, the Professor of Natural Philosophy, and wrote two joint papers with him both published in the Philosophical Magazine: Notes on the superposition of x-rays and on scattering: the J phenomenon (Part III) (February 1926) and Notes on scattered x-rays: the J phenomenon (Part V) (November 1926).

After working in Edinburgh for two years, Mackenzie was appointed to a Lectureship in Physics at Newnham College, Cambridge in 1926. The announcement of her appointment appeared in August 1926:-

In August 1926: Miss Gladys I Mackenzie, daughter of Mr I P Mackenzie of Polwarth Terrace, Edinburgh, and at present an Assistant in the Department of Natural Philosophy in the University of Edinburgh, has been appointed to the Lectureship in Physics at Newnham College, Cambridge. Miss Mackenzie graduated with First-Class Honours in Mathematics and Natural Philosophy as recently as 1924.

The Newnham College Roll letter of January 1927 (reporting for 1926) says:-

Miss G I Mackenzie has been appointed to succeed Miss Slater as Lecturer in Physics. Miss Mackenzie is an M.A. and B.Sc. of Edinburgh University, and she was a demonstrator in the Physics Laboratory of Edinburgh University at the time of her appointment.

Gladys Mackenzie joined the Edinburgh Mathematical Society in March 1925. She continued her membership when she went to Newnham College, Cambridge but she left the Society in 1930.

On 14 March 1929 Mackenzie married Wallace Russell Harper, Ph.D. who was also a physicist; they had one son. In 1930 the Newnham College Roll letter (reporting for 1929) says:-

Mrs W R Harper (Miss G I Mackenzie), who had been lecturer in Physics since 1926, resigned her post this year, and the Council appointed Miss A C Davies (D.Sc. Lond.) to succeed her.

Gladys Harper, now her married name, was a Bristol University Carnegie Research Scholar in 1929-30, then a Research Fellow from 1930 to 1933. She was employed part-time at Bristol University to undertake both teaching and research from 1933 to 1939, then she was appointed as a lecturer in the Department of Physics, a position she held until 1947. Papers published by Harper during this period include:

G I Harper and E Salaman, Measurements on the Ranges of Alpha-Particles, Proc. Roy. Soc. A127 (1930), 175-185.

G I Harper, On Crystal and Slit Systems for X-Ray Monochromatization and Spectroscopy, Proc. Roy. Soc. A151 (872) (1935), 118-141.

In the Introduction to this latter paper Harper writes:-

Crystal and slit systems are used for four purposes in X-ray physics:

(i) analysis of crystal structure, 
(ii) wave-length determinations; 
(iii) spectroscopic analysis of composite radiations; and 
(iv) the production of monochromatic beams.

The theory of (i) and (ii) has been discussed by many authors; but hitherto the theory of (iii) and (iv) has received but little attention, (see G I Harper, Proc. Camb. Phil. Soc., vol. 29 (1933, Page 408) though Richtmyer has pointed out that serious errors may arise from a neglect of the proper consideration of (iv). In this paper a systematic theory of (iii) and (iv) will be presented, and some results will be obtained that could hardly have been anticipated on general grounds. Furthermore, an application of the theory to the design of monochromators leads to notable departures from the conventional pattern.

In 1952 Harper was appointed as a part-time teacher at Channing School in Highgate, London. She taught there until 1958 when she became a part-time Lecturer in Physics at Queen Elizabeth College, London. She continued in this position until she retired in 1970, the year her husband died, when she was made an Honorary Lecturer of the College. Mary Embleton, who was a pupil at Channing School, writes [3]:-

1. First Matriculation Book, 1919-1920, Edinburgh University.
2. Graduates in Arts, 1924, Edinburgh University.
3. Mary Embleton, Gladys Isabel Mackenzie (or Harper), Personal Communication (November 2007).