October 25, 1996 11:15 Annual Reviews Frontispiece G. I. Taylor with the fluid dynamics “group” in the courtyard of the Cavendish Laboratory, (Spring 1955). Front row: Tom Ellison, Alan Townsend, Sir Geoffrey Taylor, George Batchelor, Fritz Ursell, Milton Van Dyke. Middle row: S. N. Barua, David Thomas, Bruce Morton, Walter Thompson, Owen Phillips, Freddie Bartholomeusz, Roger Thorne. Back row: Ian Nisbet, Harold Grant, Anne Hawk, Philip Saffman, Bill Wood, Vivian Hutson, Stewart Turner. November 28, 1996 9:23 Annual Reviews chapter-01 AR023-01 Annu. Rev. Fluid. Mech. 1997. 29:1–25 Copyright c 1997 by Annual Reviews Inc. All rights reserved G. I. TAYLOR IN HIS LATER YEARS J. S. Turner Research School of Earth Sciences, Australian National University, Canberra, A. C. T. 0200, Australia INTRODUCTION Much has been written about Sir Geoffrey Ingram Taylor since his death in 1975. The greater part of the published material has been written, or strongly influenced, by Professor G. K. Batchelor, who became closer to G. I. Taylor professionally than anyone else had been during his long career. Batchelor (1976a,b; 1986; 1996) has written the definitive obituaries and biographies and earlier edited the collected works, as well as bringing together the rather sparse writings of Taylor about himself and his style of research. The reader may well ask, as the present author did himself on receiving the invitation to write this article: What can anyone else, with far less direct contact, and that contact extending over a shorter period, add to what has already been provided by the acknowledged authority? On reflection, I came to the conclusion that it would be worth recording another perspective on G. I. Taylor, based on the impressions he made on me and some contemporaries who were students in Cambridge from the mid- 1950s onward. We arrived in Cambridge when he was already formally retired from the Royal Society Yarrow Research Professorship, but still very active in research. An informal group of staff and students had by then grown up around him; the theoreticians were members of the faculty of mathematics and the experimenters were in physics, but all of us occupied various spaces in the Cavendish Laboratory. Some of us were directly supervised by G. I. for a time, or collaborated with him on particular projects. (Henceforth in this article I will refer to G. I. Taylor as “G. I.” as he was called by friends and senior colleagues—students at the time addressed him more formally as “Sir Geoffrey”.) Later, in 1966, I returned to Cambridge as a staff member of the Department of Applied Mathematics and Theoretical Physics, which had been established in the interim by George Batchelor (G. K. B.) and contained 1 0066-4189/97/0115-0001$08.00 November 28, 1996 9:23 Annual Reviews chapter-01 AR023-01 2 TURNER a more formal grouping of mathematicians and experimenters working in fluid mechanics. Over this period too, there was the opportunity to observe G. I. and his interactions with those around him. A second reason for deciding to undertake this task was the opportunity it gives to say some of the things about G. K. B. and his relationship with G. I. which George has never recorded himself. It is widely recognized that G. I.’s effectiveness as a scientist, and the immediacy of his influence on many subjects, was greatly increased by the existence of the group which grew up around him. But the group was largely the creation of George. G. I. was always the “presence” who provided the historical continuity, and also a considerable sense of unity through the pride the group felt in having him in its midst, but he would not have had the interest (or the organizational skills) to bring and hold such a group together himself. My recollections of that period have been stimulated and fleshed out by discussions and correspondence over the past two or three years with many who were my contemporaries in Cambridge at that time. Many of the details recorded below, relating to both G. I.’s scientific work and our personal interactions with him, have been supplied by them, without explicit acknowledgement in the text. EARLY INFLUENCES ON G. I. TAYLOR’S STYLE OF RESEARCH I shall begin with a necessarily second hand account of some aspects of G. I.’s life, interests, and accomplishments during his boyhood and as a young man. This is highly selective, but I have attempted to pick out events and qualities contributing to the development of the distinctive style of research which has in retrospect been identified as “the spirit of G. I. Taylor.” To concentrate exclu- sively on the post–World War II years of which I have more direct knowledge would, I feel, give a very incomplete and unsatisfactory picture of G. I. and his work. G. I. came from a talented family; it is well known that his grandfather was George Boole, the originator of symbolic logic, who married Mary Everest, the niece of Sir George Everest after whom the world’s highest peak is named. One of the Boole daughters, Alice, became a self-taught mathematician like her father, another a Professor of Chemistry, and the youngest a writer, whose first novel, published in 1897, had a renewed popularity (especially in the U.S.S.R.) after the Second World War. G. I.’s father was an artist, and he grew up in a supportive home with freedom and encouragement to pursue his varied interests. His formal education began at a preparatory school in Hampstead, and his scientific bent seems to have already been formed while he was there. He and November 28, 1996 9:23 Annual Reviews chapter-01 AR023-01 G. I. TAYLOR 3 his younger brother attended the series of Children’s Christmas Lectures at the Royal Institution given in 1897–98 by Sir Oliver Lodge on “The principles of the electric telegraph.” The brothers were stimulated to construct a Wimshurst machine which they used to make X-ray pictures of the bones in their mother’s hand. At the age of twelve G. I. went on to the University College School in Gower Street. He became particularly interested in mathematics and physics, and later acknowledged the influence of the senior mathematics master there. Over the same period, G. I.’s lifelong love of the sea and of small boats began to grow, perhaps prompted initially by his father’s love of rivers, both as a painter and an oarsman. In his last year at school he designed and built a sailing dinghy in his upstairs bedroom, and (having solved the problem of getting it out of the window and lowering it to the ground) sailed it alone down to the mouth of the Thames and back. G. I. is on record as saying that while he was still at school he discovered a copy of Lamb’s Hydrodynamics in his uncle’s library, “and though I could not understand it I was fascinated by its subject matter and hoped that I would some day be able to use it in understanding the mechanics of sailing boats, a subject in which I was already much interested from the practical point of view.” He sculled and rowed while he was an undergraduate in Cambridge, and as soon as he could afford it he bought the first of a series of sailing yachts. When G. I. himself came to give the Royal Institution Children’s lectures in 1936 he chose the title “Ships.” Family influences of various kinds therefore played a great part in develop- ing G. I.’s mind and interests. In his later years he often made the puzzling statement that he saw himself as continuing the family tradition of the gifted amateur, represented by George Everest, George Boole, and his daughter Alice. In conversation it became clear that by this he did not mean to imply an unpro- fessional approach to the work accomplished, but he was stressing instead the image of a relatively untrained person who worked independently and alone for pleasure. He himself was of course far from untrained, but the last two attributes are evident in all his work—he liked doing things himself or with one collaborator or assistant, and he certainly gained enormous pleasure from doing so. In making that statement about the amateur tradition, G. I. probably also had in mind the fact that he continued throughout his life to work with the relatively simple tools he had learned early in his career, rather than mastering new techniques. His unique fresh and original approach more than compen- sated for any lack of new technical skills. In the volume commemorating G. I.’s seventieth birthday, R. V. Southwell (1956) wrote: “From whatever source de- rived, there have always been blended in G. I. the mathematician’s power of abstruse thought and the artist’s gift of perception. Few mathematicians seem to be perceptive—their minds are much too absorbed: G. I., had he felt the November 28, 1996 9:23 Annual Reviews chapter-01 AR023-01 4 TURNER urge, might have gained a different fame as a field botanist ever quick to note the beautiful and the rare.” G. I. Taylor was awarded a scholarship by Trinity College, and entered Cambridge University in 1905 to study mathematics. He obtained first-class honors in part I of the Mathematical Tripos in 1907 (he was 22nd in his year) and went on to take part II of the Natural Sciences Tripos in physics the next year, again obtaining a first and also a major scholarship at Trinity which allowed him to stay on to do research.