## The Personnel of the ACA

Writing in 1920, R. T. Glazebrook, the director of the National Physical Laboratory, recalled the events of 1909 and the inception of the Advisory Committee.29 Mr. Haldane, he said, “appealed to Lord Rayleigh and myself to know if we could help at the National Physical Laboratory. A scheme of work was suggested, and at a meeting at the Admiralty at which Mr. McKenna, then First Lord, and Mr. Haldane were present, the details were agreed upon” (435). Haldane had made the acquaintance of John William Strutt (Lord Rayleigh) while they had worked together on an earlier committee, the Explosives Committee, developing an improved and less corrosive propellant for the artillery.30 Rayleigh was a world-renowned physicist with formidable mathematical powers. He had published on aeronautical themes and had made fundamental contributions to fluid mechanics, the branch of physics that might explain how the flow of air over a wing could keep the machine in the air.31 Rayleigh was to become the president of the Advisory Committee for Aeronautics.

Given that Rayleigh was already the president of the National Physical Laboratory, so Glazebrook (fig. 1.3), as the director of the NPL, was an obvious choice to work under him as the chairman of the Advisory Committee for Aeronautics. What of the other members? There were, of course, representatives of the Admiralty and the War Office. These were Major General Sir Charles Hadden for the army and Captain (later Admiral) R. H. S. Bacon

figure 1.3. Richard Tetley Glazebrook (1854-1935). Glazebrook was chairman of the Advisory Committee for Aeronautics from its inception in 1909. A long-standing colleague of Rayleigh’s, he was also the head of the National Physical Laboratory. (By permission of the Royal Society of London) |

for the navy. (Haldane knew them both from the Committee of Imperial Defence.) Bacon was soon to be joined (and then replaced) by Captain Murray Seuter. Mervin O’Gorman, an engineer, joined the committee after his appointment as the new head of the Balloon Factory and then the Aircraft Factory.32 The remaining six members were Sir George Greenhill (mathematician), Dr. W. Napier Shaw (physicist and meteorologist), Horace Darwin (brother of Sir George Darwin and the founder of the Cambridge Scientific Instrument Company), H. R. A. Mallock (physicist), Prof. J. R. Petavel (engineer), and F. W. Lanchester (an engineer who had published a pioneering book on aerodynamics).33 The secretary of the committee was F. J. Selby, who had got to know Glazebrook when he went up to Trinity in 1888 and took classes from Glazebrook in physics and mathematics. In 1903 Selby joined the staff of the National Physical Laboratory and acted as Glazebrook’s personal secretary.34 The assistant secretary was J. L. Nayler, again of Cambridge and the NPL, who would coauthor a number of the early experimental reports.

Over fifty years after the founding of the ACA, Nayler gave a talk in which he recalled some of the personalities involved.35 He brought out clearly the closely knit character of the core group of scientists and the intellectual tradition to which they belonged. Glazebrook and Shaw, he said, had been assistants to Rayleigh in Cambridge, when Rayleigh had taken over the Cavendish laboratory after the death of Clerk Maxwell. Glazebrook and Shaw had written textbooks of practical physics together, though “they both started as mathematicians.”36 Mallock had also worked as an assistant to Rayleigh.37 Nayler went on: “Seven out of the twelve were Fellows of the Royal Society and another became a Fellow later on, three were serving officers, two were heads of aeronautical establishments. Six, including the Secretary, began as wranglers, and five were trained engineers” (1045). The term “wrangler” is an old Cambridge label for a student who came at the top of the result list in the university’s highly competitive mathematical examination called the Mathematical Tripos. The senior wrangler was at the very top of the list, followed by the second wrangler, and so on. Nayler notes that Rayleigh was a senior wrangler in 1865. Glazebrook and Shaw “were wranglers in the same year, 1876,” while Greenhill was “a second wrangler and Smith Prizeman” (1045). The award of the Smith’s Prize was an opportunity for the two or three top scorers in the Tripos to meet in a final contest in the battle for mathematical supremacy.

Nayler’s talk was given at Cambridge, which may explain some of the care taken to delineate the connections between the Advisory Committee members and the Mathematical Tripos. But we should not miss the significance or the specificity of the message. It would be difficult to overstate the centrality

of the Mathematical Tripos to the scientific life of Cambridge at the end of the nineteenth and the beginning of the twentieth centuries. Andrew Warwick’s impressive study Masters of Theory: Cambridge and the Rise of Mathematical Physics leaves no doubt about the intensity and brilliance of the Tripos tradition.38 In many areas of science in Cambridge, success in the Tripos was a precondition of scientific and academic preferment. The order of merit was published in the Times, and the senior wrangler of the year achieved celebrity status and, invariably, the offer of a college fellowship. Such success could only be achieved by intense coaching from one of a select band of brilliant but demanding tutors—men such William Hopkins, Edward John Routh, William Besant, R. R. Webb, and Robert Herman.39 Perhaps the greatest of all the coaches was Routh, whose caliber as a mathematician can be judged from the fact that, as a student, he had pushed James Clerk Maxwell into second place in the Tripos of 1854. Rayleigh had been coached by Routh, while Greenhill had been coached by Besant.

The top wranglers in turn would then become the examiners and the coaches for the next generation of students facing the rigors of the Senate House examinations. Lower-placed wranglers would often become schoolmasters and prepare their charges for mathematical scholarships to Cambridge, thus ensuring that each generation of students was better prepared than the last. This system increased the competition and forced up the standards still further. So extraordinarily high did these standards become that examiners would use their current research and their latest discoveries as the basis for their questions. The most celebrated example was a result that subsequently played an important role in the mathematical underpinning of aerodynamics. The mathematical equation, usually called Stokes’ theorem, relating circulation and vorticity, first appeared in print in the Smith’s Prize examination of 1854. The candidates were required to prove the theorem. Stated in words, the theorem is that “the circulation round the edge of any finite surface is equal to the sum of the circulations round the boundaries of the infinitely small elements into which the surface may be divided.”40 (The meaning of the technical terms involved, such as “circulation,” are explained when the circulation theory of lift is introduced in chap. 4.)

The Tripos system certainly had its critics. It placed ambitious students under great strain, and many young minds found the demands too great. Critics also argued that the questions were too difficult for all but the best, and to rectify the problem various reforms and modifications were introduced over the years. The last order of merit list was published in 1909; thereafter, candidates were placed in classes and the names listed alphabetically within the classes. There were also those who argued that the difficulty of the questions was because they were artificial and contrived so that their answers called for the mere mastery of technical tricks that had little educational value. This line taken in 1906 by G. H. Hardy, although his claims should be put in context. They were made in the course of arguments about the reform of the syllabus.41 Hardy was pressing the case for pure mathematics and rigorous foundations as against the applied mathematics and mathematical physics of the traditional Tripos.42 It was the more traditional form of the Tripos that informed the training of Rayleigh, Glazebrook, Shaw, Greenhill, and others, such as Horace Lamb, who later joined the Advisory Committee. Lamb had been coached by Routh and was second wrangler in 1872.

The scientific character of the Advisory Committee for Aeronautics, on which Haldane placed so much emphasis, was clearly weighted toward the Cambridge tradition of mathematical physics. In this connection, recall the three names that Haldane mentioned as possible leaders of the committee: Rayleigh, Moulton, and Darwin. Nayler noted that Rayleigh had been a senior wrangler, and to this one may add that Darwin, who had discussed matters with Haldane on the Saturday before the Esher committee had met, was himself second wrangler in 1868.43 What about Lord Justice Moulton? He looks the odd one out. In fact John Fletcher Moulton was senior wrangler in 1868, soundly beating George Darwin into second place and achieving higher marks than any previous Tripos candidate.44 Rayleigh, Moulton, and Darwin had all been coached by Routh. It would be wrong to say that the ACA was, or was meant to be, simply a committee of wranglers. Lanchester was no mathematician, nor were the military men, but it would not be an exaggeration to say that Cambridge wranglers were a powerful, and perhaps predominant, presence. Whether by accident or design the scientific culture of the Advisory Committee was, to a significant degree, the culture of the Mathematical Tripos.45