joseph lade pawsey, 1908-1962 - royal...

Joseph Lade Pawsey, 1908-1962

A. C. B. Lovell

1964, 229-243, published 1 November101964 Biogr. Mems Fell. R. Soc.

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JO S E P H LA D E PAW SEY

1908-1962

Biographical detailsJ oseph Lade Pawsey, one of the pioneers and outstanding exponents of radio astronomy, died in Sydney on 30 November 1962. His father, Joseph Andrews, was a farmer whose main interest was in politics—he was a foundation member of the Victorian Country Party. His mother, Margaret Lade, was at one time President of the women’s section of the party and was a prominent social worker. There was no history of previous scientific interest in Pawsey’s ancestors; on the paternal side his grandfather was an English business man, and on the maternal side his grandfather was a farmer from Kent who married Ann McConchie Lade from Dumfries.

When Pawsey’s parents married they lived on a wheat farm at Willaura, Victoria, and Joseph, their only child, was born in the neighbouring town of Ararat on 14 May 1908. Until he was 8 | years old Joe lived with his parents at Willaura. Although he did not attend school there seems no doubt that he exhibited an unusually inquiring mind which his parents made every effort to develop. In November 1916 the family moved a short distance to Stavely and here Joe attended the small State School. His schooling was interrupted two years later when the family moved again to Coleraine where there was only a half-time school. In 1919 there was yet another move to Naroghid, Victoria, and Joe attended the nearest Higher Elementary School at Camper- down eight miles away to which he travelled by pony every day for the first year. In spite of this somewhat chequered school career Pawsey won a State Junior Scholarship to Wesley College, Melbourne, in November 1922.

Pawsey entered Wesley College in February 1923 where he distinguished himself in physics and mathematics and qualified in December 1924 for university entrance after only eight years of formal schooling. He did not proceed immediately to the University but spent seven months of the following year on a tour of Europe with the Young Australian League. He returned in August 1925 to Wesley College where he won a Fred J . Cato Scholarship to Queen’s College in the University of Melbourne. Pawsey started his university career in February 1926 and after three years he was admitted to the B.Sc. degree with First Class Honours in Natural Philosophy. Pawsey was awarded the M. A. Bartlett Research Scholarship and studied for the M.Sc. degree in the School of Natural Philosophy where he was employed as a part-time demonstrator. In March 1931 he was awarded the degree with first class honours and the Dixson Research Scholarship in Natural Philosophy. The

229



230 Biographical MemoirsDixson Research Scholarship is tenable for one year in the department and Pawsey continued to work under the direction of T. H. Laby who was the Professor of Natural Philosophy at Melbourne at that time.

In this year Pawsey was awarded an 1851 Exhibition. He entered Sidney Sussex College, Cambridge, as a Research Student and pursued research work under the direction of J. A. Ratcliffe until 1934 when he was awarded the degree of Ph.D. Early in April 1934 Pawsey joined the research laboratories of E.M.I. Electronics Ltd, where he worked in the group led by E. C. Cork. He remained in this group until the end of October 1939 when he accepted an invitation to join the Radiophysics Laboratory of C.S.I.R.O. in Sydney, feeling that his specialized knowledge of the radar field should be at the disposal of his own country. He returned to Australia and at the beginning of February 1940 started work in the Radiophysics Laboratory on radar research and development.

At the end of the war Pawsey remained in C.S.I.R.O. and began his notable researches in radio astronomy. He was appointed Assistant Chief of the Radiophysics Division in 1951 and retained this post until his death. In December 1961 he accepted an invitation from the Board of Trustees of Associated Universities Inc. to succeed Dr Otto Struve as Director of the National Radio Astronomy Observatory at Green Bank, W. Virginia. Pawsey intended to take up this appointment in October 1962. In March of that year he visited Green Bank with the intention of remaining for about six weeks, but a few days after arrival his left arm and leg became paralyzed. The full extent of his illness was not immediately recognized and after partial recovery following some weeks in hospital in Washington, he proceeded to Princeton to convalesce at the home of his wife’s brother, Dr F. H. Nicoll, research physicist at the R.C.A. Laboratories. Unfortunately the recovery was short-lived, and within a few days he had to return to hospital in Boston where in the middle of May he was operated on for the removal of a malignant brain tumour. He recovered sufficiently to return to Sydney at the end of July and for the next two and half months he was able to visit the Laboratory several times a week and again take up the editing of the special radio astronomy issue of the Proceedings of the Institution of Radio Engineers (Australia), much of which was done at home. Early in October it became evident that his condition was deteriorating, but under great difficulties he continued with his work. He went into hospital for the last time on 26 October 1962.

In 1935 Pawsey married Greta Lenore Nicoll, B.A., of Battleford, Saskatchewan, Canada, daughter of John and Mabel Nicoll, who survives him together with three children of the marriage. It was a source of great satisfaction to Pawsey near the end of his life that his daughter Margaret had married a young radio astronomer (Donald J. McLean). The elder son, Stuart, is a graduate in engineering, now with a firm of consulting engineers in Sydney, and the younger son Hastings is near the end of his school career.

Pawsey was a foundation fellow of the Australian Academy of Science in 1954 and gave the first Matthew Flinders lecture in 1957. He was elected a



Fellow of the Royal Society in 1954 and received the Hughes medal of the Society in 1960. In 1953 he was awarded the Thomas Rankin Lyle medal of the Australian National Research Council, and in 1961 he received the honorary degree of D.Sc. from the Australian National University in Canberra. Pawsey had widespread international contacts and was President of Commission 40 (radio astronomy) of the International Astronomical Union from 1952 to 1958.

Early researches 1929-1934In his postgraduate research period at Melbourne 1929-1931 Pawsey

worked on atmospherics and on the accurate frequency measurement of broadcasting stations. His first published paper (1) * was on this latter topic. In the three years from 1931 to 1934 while he was a candidate for the Ph.D. degree at the Cavendish Laboratory, Pawsey worked with J. A. Ratcliffe on radio wave propagation. This work was concerned with the intensity variations of downcoming radio waves. He used a circularly polarized suppressed ground wave receiver on a wavelength of 360m and showed that the right- handed circularly polarized component of the downcoming wave was not sufficiently intense to cause fading by interfering with the other component. He devised a method of estimating the lateral deviation of the wave and found that the greatest deviations, exceeding 20°, were suffered by waves reflected from the abnormal E region. His main conclusion was that a major cause of the fading was the irregularities in the ionosphere moving under the influence of the horizontal winds at is-region heights. The results of this work formed the subject of his dissertation for the degree of Ph.D., and were published in two papers (2) (3). The conclusion regarding the horizontal movement of the irregularities opened an important topic in ionospheric physics and foreshadowed much of the later work in Cambridge and elsewhere on this problem.

Researches at E.M.I1934-1939Pawsey’s work at E.M.I. was dominated by the preparation for the

television tests at Alexandra Palace using the E.M.I. system. He was a member of the group led by E. C. Cork in I. Shoenberg’s (later Sir Isaac) research department. Cork’s group was dealing with a number of electronic problems associated with the early television development at that time, but Pawsey was concerned with the aerial and feeder design. At the commencement of this work Pawsey spent much time on field measurements of the polar diagrams of dipoles, reflectors and characteristic impedance of feeders.

The number of fines to be used in the tests had not then been settled, and it seems that the late A. D. Blumlein was the first to draw attention to the effects of mismatched feeders on the transmitted picture. Two difficulties were recognized at that early stage. First, it was necessary that the impedance of

Joseph Lade Pawsey 231

The figures in parenthesis refer to the Bibliography at the end of this memoir.



232 Biographical Memoirsthe system should be matched at all frequencies within the television sidebands, so that no part of the signal should be attenuated. Second, since in the proposed installation at Alexandra Palace, and in any foreseeable practical system, a long feeder would be needed between the transmitter and the aerial, the time of transmission would be significant compared with the shortest interval resolvable on the television picture. Any mismatch would cause reflexion along the feeder between the transmitter and aerial and eventual radiation with a time delay which would cause a double picture.

Apparently the impedance measurements made on the first aerial-feeder system erected on the roof of the research block at Hayes were most alarming, and it was with the measurements and modifications to this system, which eventually gave rise to the Alexandra Palace aerial that Pawsey was primarily concerned. The vision channel was to be on 45 Mc/s, with 405 lines, 25 pictures/s and interlaced scanning at 50 frames/s giving a side band requirement of 2-5 Mc/s. The feeder length was 450ft. so that the travel time of 0 • 5ms corresponded to a frequency in the side-band range. Pawsey designed apparatus to measure impedances at 45 Mc/s to a few per cent. At an early stage of this work it was necessary to solve the difficult problem of making a terminating resistance which would be constant and nonreactive over the frequency range 43 to 47 Mc/s. The solution of these various problems eventually led to the double ring of full-wave dipoles with the mast in the centre, erected at Alexandra Palace in the summer of 1936.

A most detailed and clear account of this work is given in the paper read before the Wireless Section of the I.E.E., by Pawsey and Cork on 7 December 1938 (4). With the major problems of the Alexandra Palace aerial solved Pawsey worked on other aspects of receiving and transmitting aerials with Cork before leaving for Australia in 1939.

The I.E.E. paper is the sole published account of Pawsey’s work during the E.M.I. period. In addition he was the author, or co-author, of 12 E.M.I. reports on aerial and feeder designs, and his name is associated with 29 patents on these subjects. Under other conditions the work described in these documents would form the subject of several published papers, but various factors of E.M.I. policy, and the competition with the Baird system led to the restriction on publication.

Wartime work in the Radiophysics , C.S.I.R.O. 1939-1945(JVote: This section has been written by Mr H. C. Minnett who was a close

associate of Pawsey during this period.)When the Radiophysics Laboratory was established in Sydney by

C.S.I.R.O. towards the end of 1939 to carry out radar research for the Australian Armed Services, J. L. Pawsey was one of the first staff members to be recruited (5). He was appointed in London in October 1939 and commenced duty in Sydney on 2 February 1940, bringing with him a quantity of radio components and test gear for the new Laboratory.

The first radar equipment to be developed in Australia was a I f metre



shore defence and gunlaying system (the Sh.D). In this work Pawsey played a prominent role and his experience at E.M.I. on aerials and feeders and electrical measurements at metre wavelengths proved invaluable. These techniques, at the time, were relatively novel and the literature sparse. To the younger graduates who formed a large proportion of the staff, his knowledge and ingenuity in this field were a constant source of inspiration.

Some of his original technical contributions to the Sh.D. system during this early period were:

16 and 36 element aerial arrays with split beam direction finding using a new rotating capacity switch (6), the first coaxial switching system to be devised for common-aerial operation, using diode switches and special impedance transformers (later gas-discharge tubes were employed) (7); a novel coaxial impedance measuring equipment which was used by the Laboratory for all development and field work for many years (8). Although his main interests were concerned with radio-frequency phenomena, he was also active in other phases of the work (receiver and circuit development) (9) and in other metre-wave projects (search-light control, anti-aircraft gunlaying and air-to-surface-vessel radars) (10). During this period, while the Laboratory was relatively small, Pawsey’s activities touched almost every aspect of the development programme.

The first experimental Sh.D. equipment was installed in May 1940 on a cliff-top Army site at Dover Heights, which in later years was to become the Laboratory’s first Radio Astronomy field station. Pawsey initiated or took part in numerous experiments with this equipment to elucidate and improve the performance of the system and its components (11). In the course of this work, he investigated the relationship between the echo cross section of a complex target, such as a ship, and its principal dimensions (12). He also suggested the possible use of medium-wavelength, vertically polarized radio waves for the detection of ships beyond the horizon (13).

The Sh.D. was a very satisfactory equipment and some 37 stations were finally installed around the Australian coast. When Japan entered the war, the Sh.D. experience and many ofits techniques and components were rapidly applied by the Laboratory to the design of an air-warning system. Because of its lightness, reliability and versatility, the equipment was probably the most successful air-warning radar in the Pacific area (5).

Before these events occurred, however, Pawsey had been made responsible for the formation of a Microwave Development Group to exploit the invention of the cavity magnetron. To study these new techniques he visited the M.I.T. Radiation Laboratory from July to October 1941. On his return his group began work on a 10cm equipment for the Navy which was very successfully demonstrated in July 1942. A number of microwave projects followed (14), culminating in the development in 1943/1944 of all the radio-frequency components for a 25cm air-warning system with height-finding facilities (15). During this period he investigated radar coverage problems and formulated a number of basic considerations concerning these (16).




234 Biographical MemoirsIn 1943 another group led by Pawsey was formed (together with a mathe

matical group under Dr J. C. Jaeger) to study super-refraction phenomena which occurred frequently on the North-West Australian Coast. R.A.A.F. and Army stations around Australia and New Guinea by regular observations supplied a great amount of data to the Laboratory for interpretation and study. During this period, Pawsey investigated diffuse cloud-like echoes at 1 Ocm from cloud-free regions of the atmosphere and suggested they were due to sea-wave echoes focused by super-refraction (17).

In spite of the pressure of wartime technical development work and increasing administrative responsibilities, Pawsey was able to investigate a number of phenomena which aroused his scientific curiosity. These included observations of 1-|- metre atmospherics from lightning flashes in July 1944 (19). These latter were apparently the first recorded observations of such echoes (20). Pawsey developed an early interest in the inherent noise level of microwave receivers (21) and in April 1944 carried out measurements with R. Payne-Scott of the very low noise levels from horns and small paraboloid aerials pointed at the sky (22). Efforts to detect the Milky Way in the region of a. and /3 Centauri were not successful. No attempt was made at the time to observe radiation from the sun but the work undoubtedly stimulated the solar measurements made immediately after the war.

Pawsey’s influence on the wartime research activities of the Laboratory cannot adequately be indicated by a statement of the major responsibilities undertaken or the reports written. Isolated from overseas centres of research, the Radiophysics Laboratory was faced with special problems particularly in the early years. All who were associated with Pawsey at the time were deeply conscious of his remarkable insight into physical problems and the informal help which he gave so generously towards their solution. It is true to say that there were few research activities in the Laboratory which did not receive and benefit from his criticism and advice.

Radio astronomy research in the Radiophysics Division C.S.I.R.O. 1945-1962At the end of the war the science of radio astronomy had not yet been

christened. Few people knew of the pre-war research of Karl Jansky and Grote Reber which had established the existence of extra-solar radio emissions, and the account of the discovery of the intense radio outbursts from the sun existed only in a secret Army document by J. S. Hey. The presence of detectable radio emissions in the thermal spectrum of the sun was known from the work of Southworth in 1942 but there had been no significant developments of these initial discoveries.

Under such circumstances it may well be asked why Pawsey decided to begin research on these problems. He has himself given the answer (23). ‘The Australian development can be traced to the concentration on radar development during World War II. This brought together in a well-equipped laboratory a group of able young physicists with experience of radio techniques. At the conclusion of the war these men found themselves without definite



commitments and anxious to establish themselves in scientific research. In some countries this situation led to an exodus of the most able people from the government radar laboratories. In Australia the high scientific reputation of C.S.I.R.O. which had been built up under men like its original leader Sir David Rivett, prevented this trend. The men were actively encouraged by the executive to develop their science within the organization. It was in this environment that the first tentative observations in radio astronomy were undertaken. These observations were immediately successful and the laboratory was encouraged to venture further into the field. These first class men obtained access to first class facilities and the subsequent developments in radio astronomy in Australia have followed from this beginning.5

Pawsey was the instigator and leader of this work. Encouraged by Dr E. G. Bowen, who was a member of Watson-Watt’s original radar team and had become the Chief of the Radiophysics Laboratory in 1945, he first used parts of radar equipment to explore the solar radio emissions, and the scope of the work soon included the observations of the moon by radar and by its thermal emission, and investigations of the terrestrial ionosphere relevant to the radio astronomical observations.

Although Pawsey inspired so much of this work his own personal research efforts were, for some years, concentrated on the problems of the solar radio emissions. Assisted by L. L. McCready and R. Payne-Scott he began work on 3 October 1945 from a 400ft. hill overlooking the sea near Sydney. The aerial was an array of 40 halfwave dipoles on a wavelength of 1 which could be rotated about a vertical axis. There was no elevation motion so that the sun could be observed only near sunrise and sunset. Radiation was observed coming from the sun which seemed to correlate with sunspot activity. Observations were also attempted on wavelengths of 50cm and 25cm. No signals were found on the former, but on 25cm a small effect was observed corresponding to a solar black body temperature of 6000 °K. The preliminary results of this work bearing the 23 October Sydney dateline were published in Nature (24) on 9 February 1946. It is a remarkable index of the growth of the subject in the subsequent years that this letter has only four references: One to Jansky’s discovery o f ‘Cosmic static5; one to the solar observations of Reber; the others to the wartime papers of the British Army Operational Research Group, and to observations by radar personnel of the Royal New Zealand Air Force.

These first observations were soon to receive adequate confirmation, but Pawsey was wide of the mark in his concluding speculation. In view of the strength of the emissions from the sun he questions the idea that the ‘cosmic static5 originated in interstellar space, and suggests that it might have its origin in those stars exhibiting radio emission phenomena like the sun. Many years were to elapse before similar phenomena were discovered in the individual stars, but it was soon recognized that the dilution factor was so great that the stellar radio emission could only contribute a very small percentage to the ‘cosmic static5.




236 Biographical MemoirsIn July 1946 only 10 months after the beginning of the solar observations,

Pawsey sent to the Royal Society an outstanding paper on his work, in which the relation of the intense radio emissions to sunspots was established beyond doubt (25). In this paper Pawsey describes the interference fringes obtained between the direct rays from the aerial on the cliff and those reflected from the sea—analogous to Lloyd’s mirror interference fringes in optics. With this system he was able to measure with some precision both the position and size of the sources of radio emission on the disk of the sun and hence the relation with sunspots was placed beyond the essentially statistical association. The intensity of the radio emission was such that Pawsey concluded, quite correctly, that the emission could not possibly arise from thermal processes in the sunspots, and he suggested that the effect was due to some gross electrical disturbance in the solar atmosphere.

At this period D. F. Martyn in Australia—stimulated by Pawsey’s work— and V. L. Ginsburg in the U.S.S.R. had independently calculated that radio emission corresponding to the kinetic electron temperatures of a million degrees should be expected from the solar corona at wavelengths of a few metres. In a short communication to Nature (26) in the autumn of 1946 Pawsey showed that his observations on a wavelength of 1 • 5m indicated the existence of such a steady million degree thermal component. In 1949 he published with Yabsley (27) a comprehensive account of these and observations made elsewhere which gave clear evidence for a relatively constant component in the wavelength range from 1cm to 4m with the apparent black body temperature increasing linearly from 104 °K at l*5cm to 106 °K at l*5m. This work was a direct confirmation of the existence of kinetic temperatures of the order of a million degrees in the solar corona.

Two survey papers by Pawsey published in 1949 are noteworthy. The first, which Pawsey read before the Radio Section of the I.E.E. in London (28) on 7 December 1949 (exactly 11 years after he had read before the same body his paper on the Alexandra Palace television aerial), was on ‘Solar radio frequency radiation’. It is typical of the extraordinary clarity and orderliness which Pawsey exhibited in his writings. In it he described the existing state of knowledge of the solar emissions and gives what is probably the first published indication that the time of the onset of bursts of radio emission depended on the radio frequency. In this paper Pawsey included 66 references, a striking index of the growth of the subject when compared with the four references of his first communication three years previously.

The second (29) on the use of radio waves in astronomical observations is devoted largely to the work at C.S.I.R.O. and shows that already after only four years Pawsey’s team had carried out important research in a wide field of radio astronomy. Particularly significant were the observations of J . G. Bolton and G. J . Stanley on the galactic radio emissions and their identification of the Crab nebula as a radio source, the observations b y j. H. Piddington and H. G. Minnett of the 1cm thermal radiation from the moon and the



success in observing radar echoes from the moon by F. J . Kerr, C. A. Shain and C. S. Higgins.

By 1950 Pawsey had formed around him a young and brilliant group of physicists and engineers, and the story of the remaining 12 years of his life is revealed in the great output of important researches by his team. Although only a small proportion carry his name as author, it was he who guided the young men towards the key problems and helped and encouraged them in the development of new instruments. This group contained B. Y. Mills—who developed the famous cross aerial that has had such a fundamental impact on the study of the remote radio sources—and W. N. Christiansen who designed the multi-element radio heliograph which by the time of the I.G.Y. in 1957 was producing radio pictures of the solar disk (30). The timeliness of his outlook was exemplified in 1951 by his cable to Nature (31) announcing that W. N. Christiansen and J . V. Hindman had succeeded in observing the 21cm neutral hydrogen line emissions only a few weeks after the initial success at Harvard and Leiden.

Although by this time Pawsey was devoting most of his energy to the encouragement and stimulation of this group a number of original contributions continued to carry his name as author. One of the most remarkable was the paper (32) describing the combined radio and optical studies made in four countries of an active solar region which led to the derivation of electron densities in the corona between 10000 and 300000 km above the photosphere.

Other items in which he joined members of his team actively in publication were the investigation of the streaming of interstellar hydrogen in the vicinity of the sun (33) and in the attempt to detect linear polarization in the galactic background (34). The former communication describes the investigation by Pawsey and his colleagues which succeeded in establishing that hydrogen gas is moving in towards the plane of the galaxy in the solar neighbourhood with speeds of 6 km/s. The second communication describes the attempt to detect the polarization in the galactic radiation which was predicted on the synchrotron theory. The observations succeeded only in setting an upper limit of 1 per cent on the frequency of 215 Mc/s used in the investigation. Indeed, although polarization in the background radiation was subsequently found by the teams in Leiden and Cambridge at a frequency of over 400 Mc/s no one has yet succeeded in measuring the polarization effect at lower frequencies.

Pawsey developed wide international research contacts and the period when he was President of Commission 40 (Radio Astronomy) of I.A.U. was a dynamic period in the growth of the new science. As a member of the I.A.U. Pawsey played a key role in the definition of the I.A.U. system of galactic co-ordinates. At the Dublin General Assembly of the I.A.U. in 1955 a Sub- Commission 33b was appointed ‘to investigate the desirability of a revision of the galactic pole and of the zero of galactic longitude’. The three other members of the commission were A. Blaauw, C. S. Gum and G. Westerhout. Their recommendations were discussed and accepted at the 1958 General

Joseph Lade 237



238 Biographical MemoirsAssembly in Moscow (35). The final report contained five papers, in two of which Pawsey was concerned as an author (36) (37). Indeed the radio data on which the new system was based originated either from Leiden or from Pawsey’s group.

The reports on the progress of radio astronomy which Pawsey wrote for the IXth (Dublin 1955) and Xth (Moscow 1958) General Assemblies (38) (39) are fine examples of their kind. Moreover, the list of reliably known discrete radio sources included as an appendix to the 1955 report was compiled at his instigation, and was subsequently published separately with a description ol the catalogue by Pawsey (40). Although long since superseded this was a most useful document at a confusing period of the subject. Pawsey also compiled the World list of radio observatories ( 1957-1958) as the result ol a request made during the Dublin assembly (41).

It is remarkable that during this period of exceedingly rapid development of his own group Pawsey found the energy and inclination to initiate research outside the main stream of the radio astronomical developments. In 1950 he initiated, with L. L. McCready and F. F. Gardner, measurements at Rankins Springs—a site free from man-made interference—on a frequency of 2 Mc/s, from which he identified and measured the thermal radiation from the ionosphere (42). It was very weak, corresponding to an effective temperature of 300 °K. This prompted a further investigation in order to find out to what height this measurement referred. This required a knowledge of the electron distribution with height which Pawsey investigated with a pulsed transmitter on a frequency of 2 #3 Mc/s (43). He found that at the site near Sydney he could regularly obtain echoes from heights of 60 to 80 km from which he derived electron densities and collision frequencies.

Pawsey travelled widely and was an invaluable member of any international gathering involving radio astronomy or related subjects. In his contacts and lectures on these occasions Pawsey was scrupulously fair in presenting the results and opinions of his own team. Nowhere was this more in evidence than in the vigorous dispute which arose between the Sydney and Cambridge teams on the cosmological interpretation of the counts of the radio sources. The paper which he gave at the Urbana (Illinois) meeting of the American Astronomical Society in August 1957 is a clear expression of the dispute as it then existed (44). Indeed the literature of radio astronomy has been enriched and enlightened by the papers which Pawsey contributed on such occasions. In 1954 he was contributing to the Cambridge Conference on the Physics of the Ionosphere (45), in 1955 to the I.A.U. Symposium at Jodrell Bank (46), in 1957 to the 5th meeting of the mixed commission on the ionosphere in New York (47), and in 1958 to the joint I.A.U./U.R.S.I. symposium on radio astronomy in Paris (48).

Within Australia Pawsey made many similar contributions to the literature. In 1955 he gave the Presidential address to Section A of the Australian and New Zealand Association for the Advancement of Science in Melbourne (49). The first Matthew Flinders lecture which he gave in May 1957 was on ‘Vistas



in radio astronomy’ (50). At the 1959 convention of the Australian Institution of Radio Engineers in Melbourne Pawsey lectured on ‘New facets in the exploration of space’ (51), and contributed a technical paper on new receivers of the maser and parametric amplifier type used in radio astronomy (52).

With S. F. Smerd, Pawsey contributed the chapter on solar radio emission in Vol. I of The Solar System published under the editorship of G. P. Kuiper in 1953 (53) and with E. R. Hill the article on ‘Cosmic radio waves and their interpretation’ in the Reports on Progress in Physics in 1961 (54). Both of these were quite outstanding contributions to the literature, and although much progress has been made in solar radio astronomy since 1953, both articles are essential reading for any student of the subject. However, Pawsey’s major contribution to the general literature was the book Radio astronomy which he published with R. N. Bracewell in 1955 (55). The clarity of the text and the fundamental approach on which it is based will ensure that it remains for a long time a standard text on the subject.

In the spring of 1961 Pawsey contributed an article to the Australian Scientist on ‘Australian radio astronomy’ (56). It was a description of the development of the subject in Australia and it now has unexpected historical value because Pawsey selected five items which had developed under his direction and which he considered to be the most noteworthy. They were(i) the work on the structure of the solar atmosphere by W. N. Christiansen,(ii) J . P. Wild’s investigation of solar activity and his delineation of the characteristics of the various types of bursts of radio emission, (iii) the work of J . G. Bolton, followed by that of B. Y. Mills on the discrete radio sources, (iv) the hydrogen line investigations of F. J . Kerr on the distribution of neutral hydrogen in the Milky Way and in the Magellanic Clouds, (v) the low frequency (10 to 20 Mc/s) measurements of the galactic radio emission by C. A. Shain. This work was associated with the development of at least four unique instruments—the Mills cross, which gave high definition for the study of the discrete cosmic radio sources, the radio heliograph or Christiansen cross which produced radio pictures of the solar disk with a resolution of 3 minutes of arc, the swept frequency receiver and interferometer which led to the study of the spectra and location of the solar radio bursts, and the multichannel receivers developed for the hydrogen line investigations.

Few would disagree with Pawsey’s assessment of these developments from which emerged results of such brilliance that the standing of Australian science in the world scene was so greatly enhanced.

Joseph Lade 239

Pawsey as an individualWhen dealing with Pawsey one felt that one was concerned with a straight

forward man of absolute honesty and integrity. His singleness of purpose was evident and against a background of happy and contented family life, his major interest was in radio astronomy. Indeed, although he was interested in sailing, he appears to have had almost no other extensive interest or hobby.



240 Biographical MemoirsAs an undergraduate he engaged in rifle shooting, and at Melbourne he gained a half Blue in 1927-1928 and a full Blue in 1929. He was awarded a Victoria Rifle Association medal in 1930, was Vice-Captain of the Melbourne team which visited Adelaide in 1930 and was subsequently Captain. In England he enjoyed cycling and made many trips around the country and, after his marriage, to the continent.

Apart from extensive publications concerning his immediate research problems Pawsey wrote little. Indeed, the only significant unrelated publication appears to be an article on the atomic bomb which he published a few months after the first explosions in 1945 (57). This restriction of interest led to an enormous concentration on his main occupation and enabled him to produce major results although so greatly involved in international travel and commitments. Professor Bart J . Bok said of him that there were ‘very few scientists in the world who will be able to look back on a life in which they have helped to produce so many distinguished scientists. The young men of Australia who are now the great names in radio astronomy, and who have helped place Australia at the top of the list in the field on a world-wide basis, all express great personal debts for the way in which Joe helped to get them started, and how he saw to it that their work came to fruition.’ Bok went on to remark on a feature that was known to all who met Pawsey, namely that he was a profound critic among radio astronomers, and that ‘he possessed great scientific vision and perseverance in seeing to it that his ideas could be put to the test, and he had more than anyone else a remarkable power to simplify complex problems and present them in a new light’.

Pawsey worked to the very end, and within weeks of his death completed the editing of the special radio astronomy issue of the I.R.E. (Australia) (58) which, with contributions from all over the world, is a fitting tribute to the great advances which he did so much to initiate and stimulate.

As an epilogue nothing could be more appropriate than the letter sent to Pawsey on 25 October 1962 signed by the 31 members of his group then in Sydney. It reveals the essence of the individual at work from those who were in a good position to judge.‘Dear Dr Pawsey,

‘Most of us in your radio astronomy group have not seen as much of you in recent months as we would have liked. When we do meet there is usually so much work to discuss that other things that ought to be said get left unsaid. We know no words to express our sorrow that you should have been stricken so suddenly in the prime of your creative life, and this letter is to let you know the extent to which we appreciate the privilege of working in your team.

‘We appreciate not only your own contributions in radio astronomy, but your rare ability to dovetail the work of many individuals into a coherent and well-directed effort. We realize that by keeping your door open to us at all times, by listening patiently to new ideas in even their earliest and vaguest forms, by discussing the most minute details of papers, and by giving so freely of your physical knowledge, experience and intuition, you have been



sacrificing most of your own research time to the success of the group as a whole. We would like to thank you for this.

‘We believe that although you can no longer play the same active role in leading the group, the Sydney radio astronomy effort (whether in R.P. or elsewhere) will continue to blossom, not merely because of the momentum you have given it over the last fifteen years, but because you have been responsible for giving a set of ordinary individuals the interest and drive to continue your work and the confidence to do well in the open field of international competition. Australian radio astronomy, like most unusual phenomena, can be traced in the main to a single cause, and we are well aware what that single cause is.

‘With the deepest respect and affection of your colleagues, Paul Wild, Kevin Sheridan, Max Komesaroff, Steve Smerd, Chris Christiansen, John Bolton, Bruce Slee, S. Suzuki, Norman Labrum, Eric Hill, Jim Hindman, Alan Carter, Keith McAlister, Frank Gardner, Lindsay McCready, Brian Cooper, Alan Weiss, Brian Robinson, Peter Scheuer, Bernard Mills, Alec Little, Jim Roberts, Frank Kerr, Dick McGee, Dick Mullaly, Don Mathewson, Joe Warburton, Jack Piddington, Charles S. Higgins, Harry Minnett, Fred Lehany.’

I am particularly indebted to Mr H. C. Minnett of the Radiophysics Division of the C.S.I.R.O. for writing the section on Pawsey’s wartime work, and to Dr E. G. Bowen, chief of the division, for the supply of copies of Pawsey’s publications while at C.S.I.R.O. Mr E. C. Cork and Dr E. L. C. White supplied me with the information about Pawsey’s work at E.M.I., and finally my sole source of information about Pawsey’s early life has been the information which Mrs Pawsey so generously sent to me.

A. C. B. Lovell

Joseph Lade 241

BIBLIOGRAPHY(1) 1930. (With W. J. W ark & R. F a l l o n .) Accurate measurement o f the frequency o f the

Carrier waves of Victoria broadcasting stations. Australian Electrical 9,163.

(2) 1933. (With J. A. R atcliffe .) A Study of the intensity variations of downcomingwaves. Proc. Camb. Phil. Soc. 29, 301.

(3) 1935. Further investigations of amplitude variations of downcoming radio waves.Proc. Camb. Phil. Soc. 31, 125.

(4) 1939. (With E. C. Cork.) Long feeders for transmitting wide side-bands, with referenceto the Alexandra Palace aerial-feeder system. J . Instn Elect. Engrs, 84, 448.

Note References (5) to (22) inclusive refer to the section on Pawsey’s wartime work in C.S.I.R.O. The abbreviation RP is to the internal Radiophysics Division report. The titles are given for those cases which Pawsey considered to be his most important work.



24.2 Biographical Memoirs(5) Australia in the War of 1939-45, Series 4 (Civil), The role of science and industry, D. P.

Mellor, Chapter 19, p. 428, Australian War Memorial, Canberra, 1958.(6) 1\ metre split-beam aerial arrays with rotating capacity switch. RP 6/1, RP 8/2, RP 13/1,

RP 17/1, RP 25/1, RP 158; RP 89/4, ‘Principle of operation of the Sh.D. rotary condenser beam swinging array’, June 1941.

(7) Common aerial operation at 1\ metres. RP 19/3, RP 19/5, RP 19/7; RP /19/1, ‘A method forusing the same aerial for both transmitter and receiver in pulse transmissions’, August 1940. RPR 51, ‘Early Australian developments in the use of a single aerial for radar transmission and reception.’ (With H. C. M in n ett , September 1946.)

(8) Coaxial impedance gear for 1\ metres. RP 96/1 ‘Concentric feeder impedance measuringequipment’, June 1941. RP 163, ‘Connecting networks between impedance measuring gear and unknown impedance.’ (With F. J. K e r r , January 1943.)

(9) Receiver and circuit development. RP 11/1, RP 11/5, RP 26/1, RP 59/2, RP 95/2.(10) Metre-wavelength radars (other than Sh.D.) RP 46/1 to 46/3, RP 58/1, RP 81/3, RP 81/6,

RP81/8, RP 116/1.(11) 1\ metre Sh.D. radar. RP 3/1, RP 5/1, RP 7/1, RP 9/1, RP 11 /5, RP 32/1, RP 34/1, RP 34/2,

RP35/1, RP67/1.(12) RP 34/4, ‘An attempt to calculate the echo field strength from the dimensions of an

object.’ (With M. I. I liffe , October 1941.)(13) RP 148, ‘Note on the possibility of the use of medium wavelength vertically polarised

waves for long range detection of ships over sea’, September 1942.Microwave development.(14) 10 cm.TI 17/5, TI 17/7, 77 35/1, 77 35/7, 7 /67 /1 , 7 /7 5 , 77 87, 7 / 82/2, 77 98.(15) 25 cm. T I 130/1.(16) Radar coverage. RP 217 ‘Considerations concerning radar coverage diagrams’, August

1944.(17) Diffuse radar echoes. RP 246/1 ‘An observation of diffuse cloud-like echoes.’ (With

F. J. K e r r , March 1945.)Lightning-flash phenomena(18) RP 49/1, ‘Observations on atmospherics from local lightning flashes on 200 Mc/s.’

(With H. C. W ebster , November 1940.)(19) 727*49/2, ‘Notes on echoes and atmospherics from lightning flashes on P band’, July 1944.(20) News item in Nature, Lond. 169, 650 (19.4.52) and ‘Radar observations of lightning on

1 -5 metres’. J. Atmos. Terr. Phys. 11, 289, 1957.Microwave noise levels(21) Discussion on ‘Noise factor of radio receivers’, H. T. Friis, Proc. I.R.E. 33, Footnote on

p. 126, 1945.(22) RP 209, ‘Measurements of the noise level picked up by an S-band aerial.’ (With

R. Pa y n e -S cott, 11 A pril 1944.)(23) 1953. Radio astronomy in Australia. J.R.A.S. Canada, 47, 137.(24) 1946. (With R. Pa y n e -S cott & L. L. M cC r e a d y .) Radio frequency energy from the

sun. Nature, Lond. 157, 158.(25) 1947. (With L. L. M cC r ead y & R. Pa y n e -S cott .) Solar radiation at radio frequencies

and its relation to sunspots. Proc. Roy. Soc. A, 190, 357.(26) 1946. Observations of million degree thermal radiation from the sun at a wavelength

of 1 • 5 metres. Nature, Lond. 158, 633.(27) 1949. (With D. E. Yabsley.) Solar radio-frequency radiation of thermal origin.

Aust. J . Sci. Res. A, 2, 198.(28) 1950. Solar radio frequency radiation. Proc. I.E.E. Part III, 97, 290.(29) 1949. The use of radio waves for astronomical observations. Aust. J . Sci. 12, 5.(30) 1957. (With W. N. C hristiansen & D. S. M ath ew so n .) Radio pictures of the sun.

Nature, Lond. 180, 944.(31) 1951. Observation of a line in the galactic radio spectrum. Nature, Lond. 168, 358.



Joseph Lade Pawsey 243(32) 1960. (With W. N. Christiansen, D. S. Mathewson, S. F. Smerd (Australia),

A. Boischot, F. J. Dennisse, P. Simon (France), T. Kakinuma (Japan), H. Dobson-Prince & J. Firor (U.S.A.). A study of a solar active region using combined optical and radio techniques. Ann. d'Astrophys. 23, 75.

(33) 1961. (With R. X. McGee & J. D. Murray.) Streaming of interstellar hydrogenin the vicinity of the sun. Nature, Lond. 189, 957.

(34) 1960. An attempt to detect linear polarization in the galactic background at 215 Mc/s.Aust. J . Phys. 13, 740.

(35) 1959. (With A. Blaauw, C. S. Gum & G. Westerhout.) Definition of the new I.A.U.system of galactic co-ordinates. Astrophys. J. 130, 702.

(36) 1960. (With A. Blaauw, C. S. Gum & G. Westerhout.) The new I.A.U. system ofgalactic co-ordinates (1958 revision). Mon. Not. R. Astr. Soc. 121, 123.

(37) 1960. (With C. S. Gum.) Radio data relevant to the choice of a galactic co-ordinatesystem. Mon. Not. R. Astr. Soc. 121, 150.

(38) 1957. Report of the commission 40 for radio astronomy. Trans. Int. Astr. Un. 9, 563.(39) 1960. Report of the commission 40 for radio astronomy. Trans. Int. Astr. Un. 10, 594.(40) 1955. A catalogue of reliably known discrete sources of cosmic radio waves. Astrophys. J .

121, 1.(41) 1958. A world list of radio observatories. Int. Astr. Un. Circular, No. 4.(42) 1951. (With L. L. McCready & F. F. Gardner.) Ionospheric thermal radiation at

radio frequencies. J. Atmos. & Terr. Phys. 1, 261.(43) 1953. (WithF. F. Gardner.) Study of the ionospheric D-region using partial reflections.

J. Atmos. & Terr. Phys. 3, 321.(44) 1958. Sydney investigations of very distant radio sources. Pub. Astr. Soc. Pac. 70, 133.(45) 1954. Radio star scintillations due to ionospheric focussing. Phys. Soc. Rep. of 1954

Cambridge Conference on The Physics of the Ionosphere, p. 172.(46) 1957. Current progress in development and results obtained with the ‘Mills Cross’ at

the radiophysics laboratory. Int. Astr. Un. Symposium No. 4, p. 123 (Cambridge 1957).

(47) 1959. The question of radio emission by the ionosphere. J. Atmos. & Terr. Phys. 15, 51.(48) 1959. Radio evidence on the large scale structure of our own and external galaxies.

IAU/URSI Paris Symposium on Radio Astronomy, p. 405 (Stanford 1959).(49) 1956. Radio astronomy. Aust. J . Sci. 18, 27.(50) 1957. Vistas in radio astronomy. Aust. Acad. Sci. Tear Book, p. 65.(51) 1959. New facets in the exploration of space. Proc. Inst. Radio Engrs Aust. 20, 381.(52) 1959. (With F. F. Gardner.) Radio astronomy and the development of receivers with

greatly increased sensitivity. Proc. Inst. Radio Engrs Aust. 20, 528.(53) 1953. (With S. F. Smerd.) Solar radio emission. The solar system, Vol. 1, p. 466.

Univ. of Chicago.(54) 1961. (With E. R. H ill.) Cosmic radio waves and their interpretation. Phys. Soc. Rep.

Prog. Phys. 24, 69.(55) 1955. (With R. N. Bracewell.) Radio astronomy. International Monographs on Radio.

Oxford.(56) 1961. Australian radio astronomy. The Australian Scientist, 1, 181.(57) 1945. Atomic power and American work on the development of the atomic bomb.

Aust. J . Sci. 8, 41.(58) 1963. Radio astronomy. Proc. Inst. Radio Engrs Aust. 24, 93.



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