Celebrating the life & work of R A Bagnold

The Early Years and First Military Career

Ralph Alger Bagnold was born on April 3rd, 1896 at the manor House, Stoke, Devonport, England. Bagnold's life was extremely colorful. Even before attending school he voyaged by sea to Jamaica where at five years of age he conducted his first recorded hydraulic experiments; consisting of construction of a working model of the household drainage system, the diversion of part of the mill stream through a rock channel, and even observation of a flood flow into the house.

Commissioned in 1915, he spent much of his army life in the Corps of Signals, originally with the Royal Engineers in France and Flanders, and later in Ireland, Egypt, India and Hong Kong. Additionally, Bagnold's nature led to voyages into the Atlantic from Ireland, forays into the Libyan Desert and the Sinai, to Kashmir, and to Siam and Cambodia. Forays into the desert included driving Model-T Ford cars the length of the Sinai, followed by driving a Ford truck from India to Egypt across the Baluchistan Desert, Persia and the Syrian Desert. After returning to England where life appeared "very tame and narrow" in 1932 he became involved in a cross country journey of 6000 miles in Model-A Fords to the Northern Sudan. He retired from the army in 1935.

Bagnold wrote his first book, Libyan Sands while in Hong Kong. Following his retirement he carried out wind tunnel experiments in the Hydraulics laboratory, Imperial College, London. He later spent eight days alone in the desert waiting for a sandstorm to get some "really reliable" field measurements. He then wrote his second book The Physics of Blown Sand and Desert Dunes, though it was not published until 1941. During this period he wrote hallmark papers on 'The Movement of Desert Sands", 1936, “The Size-grading of Sand by Wind", 1937, "Grain Structure of Sand Dunes and its Relation to Their Water Content", 1938 and an "Interim Report on Wave-Pressure Research". 1939. Just prior to World War II Bagnold began experiments at Imperial College to study the motions of solids moved by water flows. These studies were resumed after the War.

World War II and the Long Range Desert Group (LRDG)

Brigadier Bagnold was recalled immediately after the war began. He was posted to East Africa, but due to a maritime accident he landed in Cairo, Egypt. There he was astonished to find a complete ignorance of the desert country beyond Nile cultivation. Upon presenting his ideas to General Wavell he was given carte blanche to design, create and train within six weeks a small, private, self-contained army capable of operating anywhere in the uninhabited interior of Libya. This was the origin of the Long Range Desert Group (LRDG) which Bagnold commanded far behind enemy lines. By the time the German Africa Corps entered the war the LRDG had an observation post within hundreds of feet of their main supply route to the front. When asked by Luna Leopold how his men remained undetected so close to the enemy, he replied "In the desert friend and foe alike dressed in khaki. We were so close to the road and so far behind their lines (over 800 miles) that they took us for comrades who had just stepped off the road to answer the call of nature!" The following extract from General Wavell's official dispatch of October 1941 highlights aspects of the Bagnold's military career:

"I would like to take this opportunity to bring to notice a small body of men who have for a year past done inconspicuous but invaluable service, the Long Range Desert Group. It was formed under Major (now Colonel) R. A. Bagnold in July 1940 to reconnoiter the great Libyan Desert on the western border of Egypt and the Sudan. Operating in small independent columns the group has penetrated into nearly every part of desert Libya, an area comparable in size with that of India. Not only have the patrols brought back much information, but they have attacked enemy forts, captured personnel, transport and grounded aircraft as far as 800 miles inside hostile territory. They have protected Egypt and Sudan from any possibility of raids, and have caused the enemy, in lively apprehension of their activities, to tie up considerable forces in the defense of distant outposts. Their journeys across vast regions of unexplored desert have entailed the crossing of physical obstacles and the endurance of extreme summer temperatures, both of which would, a year ago, have been deemed impossible. Their exploits have been achieved only by careful organization and a very high standard of enterprise, discipline, mechanical maintenance and desert navigation. The personnel of these patrols was originally drawn almost entirely from the New Zealand forces; later officers and men from British units and from Southern Rhodesia joined the Group. A special word of praise must be added for

the R. A. 0. C. fitters whose work contributed so much to the mechanical endurance of the vehicles in such unprecedented conditions." The LRDG was later the basis for the television show "The Desert Rats".

Back to the Physics of Sediment Transport by Water

Following World War II Brigadier Bagnold had a brief two year position as Director of the Shell Research Centre, near Chester, England, during which time he was partially instrumental in establishing the Hydraulics Research Station at Wallingford. He soon decided to return, however, to his studies of the movement of sediment by water. Hallmark papers during this period of his career included "Motion of Waves in Shallow Water, Interactions Between Waves and Sand Bottoms", 1946, "Measurement of Very Low Velocities of Water Flow", 1951, and "Experiments on the Gravity-Free Dispersion of Large Solid Spheres in a Newtonian Fluid under Shear", 1954.

He then turned his attention to the problems of sediment transport by water and was invited by Luna Leopold, head of the Water Resources Division of the USGS to help "stir the pool of complaisant tradition with the stick of inquiry". A series of classic papers resulted during the 1960's including "Flow Resistance in Sinuous or Irregular Channels". 1960, "Some Aspects of the Shape of River Meanders", 1960, "Beach and Nearshore Processes: The Mechanics of Marine Sedimentation and Littoral Processes", 1963. and "An Approach to the Sediment Transport Problem from General Physics", 1966. Later key papers include “The Nature of Saltation and of 'Bedload' Transport in Water", 1973, and "An Empirical Correlation of Bedload Transport Rates in Flumes and Natural Rivers", 1980. On the occasion of his 90th birthday Bagnold published 'Transport of Solids by Natural Water Flow; Evidence for a Worldwide Correlation" in 1986.

Awards

Brigadier Bagnold claimed "he was never a "keen soldier" in the sense of having high rank as a primary objective" and that he "would rather become a Fellow of the Royal Society than a major general". In 1944 he was elected Fellow without even knowing that his name had been submitted. Other awards include the Gold Medal of the Royal Geographical Society in 1934, the G.K. Warren Prize by the U.S. Academy of Sciences in 1969, the Penrose Medal by the Geological Society of America in 1970,

the Wollaston Medal from the Geological Society of London in 1971, the Fellowship of the Imperial College in 1971, an honorary D.Sc. by the University of East Anglia in 1972, the Sorby Medal from the International Association of Sedimentologists in 1978, an honorary D.Sc. by the Danish University of Aarhus in 1978, and the David Linton Award from the British Geomorphological Research Group in 1981.

Conclusions

Especially well known for his pioneering work on wind blown sands in deserts Brigadier Ralph Alger Bagnold has also published dozens of papers on sediment transport in the oceans, on beaches and in rivers. Many of these papers remain standard works on their topics and have formed the basis for much of the progress achieved by subsequent researchers. For example, his book, The Physics of Blown

Sands and Desert Dunes was used by NASA in the design of the Lunar Land Rover and the sand-driving mechanism for the exploration of the Martian landscape. In their personal search for the Truth contemporary researchers will always benefit from reading the hallmark papers of Ralph Bagnold, who has striven to understand and explain the fundamental processes of sediment transport, rather than merely predict the magnitude of the sediment load carried by a particular fluid flow. Bagnold’s approach also serves as a blueprint of how to conduct basic research in this difficult and often frustrating field. At each stage in his exploration of sediment transport he identified and isolated critical portions of the theory, and then attacked them experimentally to provide the exponents and coefficients required to proceed. Often when confronted by the lack of suitable experimental equipment, Bagnold simply redirected his sharp mind and skilled hands to the invention and construction of the necessary apparatus. Working first in the Libyan Desert and later in his large workshop at Rickwoods, England, he produced a series of ingenious devices often from scrap metals. His is the "classical" approach to science and it has borne fruits of timeless value and applicability bounded only by the limits to Newtonian physics.