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Geophysical Instruments in Australia’s

National Historical Collection

Denis Shephard

narioka@grapevine.com.au

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Abstract

Australia’s National Historical Collection includes a collection of about 750 geophysical instruments that has been described as ‘the most extensive assembly of historic geophysical apparatus in Australia’.  As a whole the instruments in the collection represent the full range of survey and laboratory work carried out by Australian national government geophysicists through the 20th-century.  Several of the instruments also relate directly to Australia’s relations with the international scientific community.  This article provides a general overview of the collection as well as a closer look at some selected instruments from the collection.

 

Introduction

Australia’s National Historical Collection (NHC), which is cared for by the National Museum of Australia (NMA), includes about 750 geophysical instruments.  The core of the collection comprises superceded and out-of-date equipment assembled by Bureau of Mineral Resources, Geology and Geophysics (BMR) staff from the 1950s.  These instruments, described in 1978 as ‘the most extensive assembly of historic geophysical apparatus in Australia’ (Ref. 1), were transferred to the newly established Museum of Australia (now NMA) for inclusion in the NHC in July 1986.  Since that time the collection has been significantly expanded through the addition of instruments from the Australian Geological Survey Organisation (AGSO) and Geoscience Australia (GA), successor organisations to the BMR.  The collection now comprises instruments representing the full range of survey and laboratory work carried out by Australian national government geophysicists through the 20th-century.

This article, a re-worked and updated version of previous articles and papers (Ref. 2), provides a general overview of the collection as a whole as well as a closer look at some selected instruments from the collection.  It begins with a brief review of the evolution of Australia’s national geological survey.

Australia’s National Geological Survey

General histories of Australia’s National Geological Survey are provided by Crespin (1971), Johns (1976) and Wilkinson (1996) (Ref. 3), whilst a number of articles in Preview and other journals – too numerous to list here – provide detailed stories of specific initiatives.

Geological Surveys were formed in the six Australian colonies (now states) in the second half of the nineteenth century whilst the first national geological staff appointment was that of Evan Richard Stanley as Government Geologist in Papua in 1911.  Early national activity included

  • establishment of a magnetic observatory at Watheroo, Western Australia, by the Carnegie Institution of Washington’s Department of Terrestrial Magnetism (DTM) in 1919;
  •  the Imperial Geophysical Experimental Survey (IGES) which tested the applicability of various geophysical survey methods under Australian conditions between 1928 and 1930;
  • the Aerial, Geophysical and Geological Survey of Northern Australia (AGGSNA) which investigated selected areas of promise for mineral discovery in northern Australia between 1934 and 1941;
  • the Minerals Production Directorate, established in 1941 to control and aid wartime mineral and oil production then, from 1944, the search for commercial uranium deposits; and,
  • the Mineral Resources Survey, established in 1942.

The Bureau of Mineral Resources, Geology and Geophysics – incorporating the former Mineral Resources Survey and the Mineral Production Directorate – was established in 1946 to systematically map the geology of mainland Australia.  In the late-1970s, the BMR’s primary role moved toward strategic research, with an emphasis on the search for offshore petroleum reserves.  The Bureau became the Australian Geological Survey Organisation in 1992 then, in 2001, Geoscience Australia.  GA combined the previously separate agencies of AGSO, the Australian Surveying and Land Information Group (formerly Australian Survey Office and National Mapping) and the Australian Centre for Remote Sensing.  There are instruments representing all these developments in the NHC.

 

Collection Overview

The collection includes instruments from the full scope of exploration geophysical methods as practised by the BMR, its predecessors and successors, through the 20th-century.  Several of the instruments also relate directly to Australia’s relations with the international scientific community through both the DTM and the sub-Antarctic and Antarctic geophysical observatories.  Exploration geophysics ‘is the art of applying the physical sciences to the study of the structure and composition of those layers of the earth which are sufficiently shallow to be exploited by man.’ (Ref. 4)   The relevant principles include gravitational and magnetic attraction; reflection and refraction theories (for seismic work); parts of electricity and electromagnetic theory; and, the physical properties of radioactive material.  These methods do not identify economic mineral deposits rather they indicate likely locations that then have to be tested using other techniques.

The article will review the collection based on the different geophysical prospecting methods.

 

Electrical Prospecting Equipment

Electrical and electromagnetic methods measure either natural or artificially created electrical and/or magnetic fields.  They are used to derive some characteristic of the sub-surface, generally the resistivity or the conductivity. The former is measured directly using electrodes set in the ground and a direct-current resistivity meter; the latter inductively using an electromagnetic instrument such as a hand-held metal detector.  These methods can also be used in the air or at sea. (Ref. 5)

Electrical and electromagnetic equipment in the collection includes (Ref. 6)

  • a set of Turam equipment used at Ravensthorpe, Western Australia, in 1965;
  • a set of Slingram equipment;
  • an electromagnetic compensator system built by the BMR to the basic design of instrumentation used by the AGGSNA;
  • McPhar high sensitivity and induced polarisation equipment;
  • Scintrex electromagnetic equipment (Fig. 1);
  • electromagnetic gun equipment;
  • earth megger testers;
  • several ratiometers; and,
  • a Hunting-Canso airborne electromagnetic system that was used by Adastra-Hunting under contract to Riotinto Exploration Company in Western Australia and Queensland in about 1956-57.
Scintrex electromagnetic drill-hole probe

Fig.1   Scintrex DHP-4 electromagnetic drill-hole probe.  Image by Denis Shephard, 2010

Gravity Equipment

Gravity methods involve measuring variations in Earth’s gravitational field.  They include the exact measurement of acceleration due to gravity at a network of surveyed points over an area and the measurement of the rate of change in the acceleration due to gravity along lines between points.  These methods are used primarily as a reconnaissance tool in the search for oil; to provide control in seismic prospecting; and, as a secondary method to other techniques in mineral exploration.  Absolute gravity measurements are generally carried out at fixed installations by accurately timing a swinging pendulum or a falling weight.  Torsion balances, pendulums and gravimeters (or gravity meters) have been used to measure relative gravity. (Ref. 7)  Dooley and Barlow trace the history of gravimetry in Australia up to the mid-1970s. (Ref. 8)

Gravity equipment in the collection includes (Ref. 9):

  • Thyssen gravity meter No 66 and Holweck-Lejay inverted pendulums that were used by Shell (Queensland) Development Pty Ltd in southwest Queensland in 1940-42;
  • several Askania torsion balances, including one which was presented to the BMR by the Vacuum Oil Company in the 1970s;
  • part of a North American marine gravity set that was used in offshore survey work along the north and east coast of Australia in the late-1950s;
  • Geophysical Institute of Japan pendulum equipment that was used to link Tokyo and Melbourne in 1962; and,
  • Oertling gradiometer No 21636 (Fig. 2).
It is possible to trace the working history of the Oertling gradiometer.

Oertling gradiometer No 21636

Oertling gradiometer

Fig. 2  Oertling gradiometer No 21636, 2001.
Image courtesy of National Museum of Australia

This is one of three built by Ludwig Oertling Ltd in 1928 (Ref. 10) and was used in gravity prospecting work by the IGES, the New South Wales Department of Mines and by the AGGSNA.  The Imperial Geophysical Experimental Survey was established as a joint effort of the British Empire Marketing Board and the Australian Government in 1927 to ‘test the applicability of various geophysical methods under field conditions in Australia.’ (Ref. 11)  It trialled electrical, gravimetric, magnetic and, to a limited extent, seismic prospecting methods in widely separated areas across Australia.  Gravity surveys were carried out on gold deep leads at Gulgong, New South Wales, brown coal deposits at Gelliondale, Victoria, and on oil structures at Lakes Entrance, Victoria.  For this work the IGES was equipped with an Eötvös torsion balance and two Oertling gradiometers.  The two gradiometers cost £375 each which, together with the spare wires, three huts and surveying instruments brought the initial expenditure on gravity equipment to £1240. (Ref. 12)  The suitability of the torsion balance and gradiometers to Australian conditions was assessed with the latter being found to be:
  1. more easily transported to the place of operation and between stations;
  2. provide a quicker measurement of gravity gradient;
  3. be less sensitive but not significantly so; and,
  4. give satisfactory readings in day time whereas the torsion balance could only be used at night.

Neil Lewis, in charge of the gravity work, concluded that the gradiometer, despite some problems with preliminary adjustments and calibration, was ‘quite satisfactory for use under Australian field conditions’. (Ref. 13)

It appears that gradiometer 21636 was later used by the AGGSNA to investigate the coalfield at Blair Athol, Queensland in 1939 and by the New South Wales Department of Mines to map the southern extension of the ore body at Broken Hill in 1939-40. (Ref. 14)

 

Magnetic Equipment

Magnetic methods measure variations in Earth’s magnetic field caused by changes in the sub-surface geological structure or by differences in the magnetic properties of near surface rocks.  They have much in common with gravity methods although they are generally more complex because of the more erratic and localised nature of the magnetic field.  Magnetic methods are the most versatile of all geophysical prospecting techniques and can be used on land, at sea and in the air.  The earliest devices used for magnetic exploration were variations of the mariner’s compass.  More modern instruments include the magnetic variometer, magnetic balance, fluxgate magnetometer, proton- precessor magnetometer and the optical-pump magnetometer. (Ref. 15)

Magnetic equipment in the collection includes (Ref. 16):

  • Askania and Schultz earth inductors;
  • Askania torsion magnetometer No 571909, declinometer No 580333 and mirror galvanometers nos 5111135 and 5111138;
  • an Elliott Brothers Kew pattern magnetometer;
  • aeromagnetic equipment including a fluxgate magnetometer of the type developed by Gulf Oil in 1951 and used by Hunting Adastra during aeromagnetic work for the BMR from about 1956 until the early 1960s:,
  • a Littlemore flux-gate magnetometer first used by the BMR in an aeromagnetic survey of the Gippsland Basin, Victoria, in 1951;
  • Sharpe personal torsion magnetometer No 142, dating from the 1960s;
  •  several quartz horizontal magnetometers used at Macquarie Island, Toolangi, Mawson and Watheroo geophysical observatories;
  • several BMZ magnetometers used at Mawson, Casey, Port Moresby and Casey geophysical observatories;
  • Askania horizontal force variometer No 520313 that was part of the equipment in the Mundaring Geophysical Observatory, Western Australia;
  • 15 Hilger and Watts variometers dating from the 1930s to the 1950s;
  • dip circles by Sharpe (No 258), Dover-Charlton (No 201) and Dover-Charlton-Kent (No 149);
  • three CIW theodolite-magnetometers; and
  • an EDA fluxgate magnetometer.

The three theodolite-magnetometers and EDA fluxgate magnetometer are particularly rich in detail about their construction and use.

Carnegie Institution of Washington theodolite-magnetometers nos 7, 16 & 18

Originally part of the DTM’s stock of magnetic survey equipment these three instruments were used in various places around the world before being transferred to the BMR.  Together they illustrate part of the story of the DTM’s four decade ‘magnetic crusade’.

The Carnegie Institution of Washington established the Department of Terrestrial Magnetism in April 1904, to investigate ‘the magnetic and electric condition of the Earth and its atmosphere’ on a world-wide scale.  Thus began DTM’s ‘crusade’ to extend the existing haphazard knowledge of Earth’s magnetic field.  From its headquarters in Washington the DTM sponsored hundreds of land expeditions in some of the world’s most remote places; sent two vessels – the Galilee and the Carnegie – around the world’s oceans; and, established and operated two geophysical observatories, at Watheroo (Western Australia) in 1919 and at Huancayo (Peru) in 1922. (Ref. 17)

The DTM developed a ‘light portable type’ of magnetometer (Figs. 3 & 5) for their land-based work.  Enclosed in a timber case in which each individual component had its specific place, the magnetometer could be easily assembled into an instrument that quickly and accurately measured the three magnetic elements as well as astronomical elements. (Ref. 18)

Fig. 3 Theodolite-magnetometer in DTM’s workshop, ca. 1908=1910

Fig. 3   A theodolite-magnetometer set up in the DTM’s workshop, 190?  Established in 1908 the workshop was under control of chief
instrument maker Adolf Widmer.  Image courtesy of Carnegie Institution of Washington, Department of Terrestrial Magnetism.

The stories of CIW-7, CIW-16 and CIW-18 illustrate the usefulness of the DTM’s instrument as well as the hardships and challenges faced by the magnetic observers who used them.

Theodolite-magnetometer CIW-7, one of nine DTM-designed instruments assembled in the workshop of Bausch, Lomb and Saegmuller in New York, was acquired by the department in 1908.  It was used briefly in Canada before being assigned to William Sligh who departed Washington in November 1908 on a three-year expedition that took him to Cuba, Central America, the Middle East, northwest Africa and Sierra Leone.  Six years after Sligh’s return to Washington, CIW-7 was sent to Watheroo Magnetic Observatory where it was installed as a standard instrument, in 1919.  In July 1947, the CIW gifted Watheroo Magnetic Observatory to the Australian Government and its operation was taken over by the BMR.  It was closed in March 1959 and replaced by a new establishment at Mundaring, also close to Perth. (Ref. 19)

Theodolite-magnetometer CIW-16 was assembled in the DTM workshop in May 1911 at a cost of USD650.  It was used in Central America (1912 & 1940), South America (1912), Canada (1913), West Africa (1914-15 & 1922-27), South America (1919 & 1931-33), on the Donald MacMillan Baffin Island Expedition (1921-22) (Fig. 4), East Africa (1934), on the Louise Boyd Arctic Expedition (1941), North America (1943) and at Huancayo Magnetic Observatory (1929-31 & 1946-48) before being written off the books in May 1949. (Ref. 20)  When, how and why it came to Australia and where it was used here is still being investigated.

Fig. 4 Aboriginal, Took-a-key, viewing with theodolite-magnetometer

Fig. 4   Took-a-key, a norther Canadian aboriginal, viewing the azimuth with
theodolite-magnetometer CIW-16 at Cape Dorset, Baffin Land, August 1922.
Image courtesy of Carnegie Institution of Washington, Department of Terrestrial Magnetism.

 

Theodolite-magnetometer CIW-18 (Fig. 5) was assembled in the DTM workshop in 1916 and used in China (1916-17), East Africa (1930-34) and, from 1936, in Australia mainly with the AGGSNA where it was issued to Lew Richardson, leader of the magnetic survey group within the AGGSNA. (Ref. 21)  He continued using CIW-18 after the end of AGGSNA, including investigations for the Royal Australian Air Force and Royal Australian Navy at Sydney (1943), Brisbane (1944), Fremantle (1944) and Darwin (1944). (Ref. 22)  CIW-18 was subsequently used by Noel Chamberlain on the Cocos-Keeling Islands in 1946; on Heard and Macquarie islands and on Iles de Kerguelen in 1948 and 1950; and, in Port Moresby Magnetic Observatory, Papua New Guinea, in 1960-61. (Ref. 23)

Fig. 5 Theodolite magnetometer

Fig. 5   Theodolite magnetometer CIW-18, 2012.
Image courtesy of National Museum of Australia

 

EDA FM-105B fluxgate magnetometer

This magnetometer (Fig. 6) was used in the search for the South Magnetic Pole in the Southern Ocean by geomagnetician Charles Barton and others, firstly on MV Icebird in 1985 and, secondly, on MV Hubert Wilkins in 2000.  Just before midnight on 23 December 2000 the South Magnetic Pole was observed to be only 1600 meters from the Hubert Wilkins at 16°40’S latitude and 138°00’E longitude.  This was the closest any geomagnetician had come to the pole.  Another major step forward had been made in understanding the movement of Earth’s magnetic poles. (Ref. 24)

Fig. 6 EDA fluxgate magnetometer exhibited in ‘Quest for the South Magnetic Pole’

Fig. 6  EDA fluxgate magnetometer displayed in ‘Quest for the South Magnetic Pole’ exhibition, at the South Australian Maritime Museum, July 2009.
 Image courtesy of South Australian Maritime Museum

 

Radiometric Instruments

Radiometric methods use instruments that count electrical impulses generated by the discrete nuclear process.  The time-rate of counts generated is a measure of radioactivity strength.  This method was first used in the late 1930s in oil well logging then, in the late-1940s, in the search for uranium deposits.  Survey is by hand-held ratemeter (using Geiger or scintillation counters), airborne detector (using scintillometers) or by well logging.  The BMR was heavily committed to the search for uranium in the 1950s and purchased a range of equipment in Australia and from the United Kingdom, Holland, Canada and the United States of America. (Ref 25)

Radiometric equipment in the collection includes (Ref. 26)

  • Chalk River and Canadian Aviation Electronics scintillometers (Fig. 7);
  • instruments made by the Atomic Energy Research Establishment at Harwell in the United Kingdom and used at Rum Jungle, Northern Territory, including a Type 1125A end window assay and a Type 144A ratemeter for surface exploration as well as an airborne scintillograph for aerial work; and,
  • portable Geiger counters and ratemeters, including several developed and marketed by Austronic Engineering Laboratories in Melbourne.
Fig. 7 Canadian Aviation Electronics scintillometer
Fig. 7  Canadian Aviation Electronics Model 965 scintillometer, 2001.
Image courtesy of National Museum of Australia

 

Seismic and Seismological Equipment

The seismic method utilises shock waves induced by explosive charges in shallow bore-holes.  These waves travel through the rocks and are reflected or refracted to the surface from different depths and collected by detectors at known points.  The depths of reflecting or refracting strata can be calculated from the arrival time and character of the recorded waves.  Seismic methods are widely used in oil and gas exploration work. (Ref. 27)  The seismic equipment in the collection includes: (Ref. 28)

  • a Cambridge Institute sound-ranging set that was used in Australia by the IGES, then altered and added to in 1941;
  • Midwestern 12-channel seismic equipment;
  • a Cambridge universal vibrograph recorder that was manufactured in 1944 to a design originating in 1925;
  • Wood Anderson seismic observatory equipment;
  • a Leet Blumberg seismograph;
  • a Jules and Richard mechanical seismograph;
  • a Sun 2 computer system; and,
  • a Benioff seismometer.

Of particular significance is the Sun 2 computer system and the Benioff seismometer.

Sun 2 computer system

Known as ‘Annie’, the Sun 2 computer system (Fig. 8) was installed in the BMR’s seismological centre in Canberra in 1984 where it played a key role in the Bureau’s nuclear weapons testing monitoring program by retrieving and analysing data from the Alice Springs, Northern Territory, seismic array which was jointly run with the United States of America Air Force.  By 2002, however, it was no longer able to meet the storage demands of the work and was replaced by a system of larger capacity. (Ref. 29)

Fig. 8 Sun 2 computer system

Fig. 8   Sun 2 computer system in storage. Image by Denis Shephard, 2001

 

Benioff Seismometer

Seismometers measure and record the seismic waves that pass through the earth to monitor ground movements.  The Benioff seismometer (Fig. 9) was imported from the United States of America in about 1956 and installed in the old Melbourne Observatory.  This proved to be an unsatisfactory site as there was too much electrical interference so the seismometer was shifted to a more remote site at Green Mount near Toolangi, Victoria, in 1962.  Before the station went automatic in the 1980s Ron Biggs, a local farmer, took daily readings for despatch to the seismic section of the BMR. (Ref. 30)

Fig. 9 Benioff seismometer

Fig. 9   Benioff seismometer (part).
Image by Denis Shephard, 2002

 

Miscellaneous Instruments

There is a wide range of miscellaneous instruments in the collection including theodolites, plane tables, alidades, sextants, two Topoplastic circular slide rules (V = Vo + at and V = Vo + Kz) and a Unicom electronic microscope. (Ref. 31)  A select few are examined below.

Chronometers

There are several chronometers – both marine and survey – in the collection.

Dent marine chronometer No 53862 (Fig. 10) was purchased by the DTM ‘complete with gimbals and case’ at a cost of US $170.80 and received into store on 20 May 1905.  It was issued to William John Peters on the Galilee in December 1905 where, apart from short periods ashore for overhauling and rating, it remained until the decommissioning of that vessel in 1908.  Subsequently it was issued to the Carnegie, under charge of Peters then, from May 1914, James Percy Ault. It stayed on the Carnegie until November 1921 when it was returned to store.  Dent 53862 was issued to Watheroo Magnetic Observatory in May 1925.  About this time it was removed from its timber case and is now contained in a round leather one. (Ref. 32)

Fig. 10. Dent Marine chronometer no 53862

Fig. 10   Dent Marine chronometer no 53862, 2001.
Image courtesy of National Museum of Australia

Survey chronometer No 18786 (Fig. 11), a standard two-day machine, was made by Thomas Mercer in about 1949/50, and used at Mawson Magnetic Observatory in Antarctica, in the 1970s. Like the other Mercers with Antarctic connections, this machine is housed in a locally made case and was used as a laboratory time-reference, after being set by radio time signals. On at least one occasion, in January 1976, its time was checked against a reference signal broadcast from Radio VNG in Australia. The receiving and broadcasting equipment of Radio VNG are now in the NHC. (Ref. 33)

Fig. 11 Mercer survey chronometer No 18786

Fig. 11   Mercer survey chronometer No 18786.
Image by Denis Shephard, 2006

Monroe Odograph

The Monroe odograph was developed by the United States of America’s Corps of Engineers during WWII as a vehicle navigation system.  It could plot to any scale between 1 to 20,000 and 1 to 500,000, making it possible to draw a route map showing all the roads in a specified area to the same scale as a topographic map and with an accuracy of one to three percent.  Its proposed use by the BMR is still being investigated – the various components are still in their original packing. (Ref. 34)

Waterworth plotting stereoscope

This plotting stereoscope was designed and built by Eric Waterworth, optical & scientific instrument maker of Hobart, in consultation with Professor Samuel Carey of the Geology Department at the University of Tasmania in the early 1950s.  It was used for geological photo-interpretation work but was also suitable for forestry work.  The stereoscope was purchased by CSIRO Forest Research at Yarralumla and transferred to the BMR in 1983. (Ref. 35)

LFE Corporation plasma asher

Plasma ashers remove organic material from other material through a process of micro incineration.  This one was used in the Organic Geochemistry Laboratory of Offshore Petroleum Exploration at GA.  The principal work of the laboratory is analysis of sediments to assist in the search for offshore petroleum deposits. (Ref. 36)

 

Conclusion

In May 1978, Dr Peter Sydenham argued that the collection (as it was then) was a ”

… significant part of Australia’s technological heritage…(that should) be made more available to the public, for it presents a significant amount of national activity in the more modern era of the earth sciences (Ref. 37).

It is only in recent times, however, that Sydenham’s plea has been acted upon. About 500 instruments from the collection are currently displayed on the NMA’s website (www.nma.gov.au/collections  and enter “geophysical” in the search field to access the collection currently accessible), but with only minimal information about each. Unfortunately there is no reference to the richness of stories behind either the collection as a whole or of individual instruments within the collection. Beyond the website, only about ten instruments from the collection have ever been placed on display. The ‘Rocks to Riches’ module of the Museum’s Nation Gallery (now closed) included about eight instruments whilst the ‘Quest for the South Magnetic Pole’ travelling exhibition, developed by the South Australian Maritime Museum in 2010, included the EDA fluxgate magnetometer (Fig. 6) and dip circle 149.

This, and preceeding, articles, are only an introduction to the collection of geophysical instruments in Australia’s National Historical Collection. Much more could (and in the author’s opinion should) be done to make this nationally significant collection of geophysical equipment ‘more available to the public’.

 

Acknowledgements

Thanks to Anne Kelly, Denis French and Jason McCarthy of the National Museum of Australia for providing access to and images of instruments. Special thanks to Shaun Hardy for providing access to and guidance in use of the archival and photographic collections of the Department of Terrestrial Magnetism in Washington D.C. and for providing reproduction quality copies of field-work images from the latter.

 

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References:

  1. P.H. Sydenham, ‘Early Geophysical Practice. The BMR instrument collection’, BMR Journal of Australian Geology & Geophysics, 1/3 (1978): 241-48.
  2. Denis Shephard, ‘Geophysical Instruments in the National Historical Collection’, Preview, 163 (April 2013): 21-27: and, Denis Shephard, ‘Places and Cases.  Some Geoscientific Surveying Instruments from the Collection of the National Museum of Australia’.  Presentation to XXVII Scientific Instrument Symposium, Lisbon, 16-21 September 2008.
  3. Irene Crespin, ‘Recollections on the Growth of Commonwealth Interest in the Geological Sciences’, Records of Australian Academy of Science , 2/2 (1971): 29-46; R. K. Johns (ed), History and Role of Government Geological Surveys in Australia, Government Printer, Adelaide, 1976); and, Rick Wilkinson, Rocks to Riches.  The story of Australia’s national geological survey (Allen & Unwin, Sydney, 1996).
  4. J.J. Jakorsky, Exploration Geophysics (Trija Publishing, Los Angeles, 1950/1940): 1.
  5. Milton B. Dobrin, Introduction to Geophysical Exploration, 2nd Ed. (McGraw-Hill Book Company, New York, 1960/1952): 339-73; and, Ibid: 437-638.
  6. National Museum of Australia Collection File (Bureau of Mineral Resources)
  7. Ibid. ref. 5, 169-183 & 200-17; and, ibid. ref. 5, 247-436.
  8. J.C. Dooley and B.C. Barlow (1976) ‘Gravimetry in Australia, 1819-1976’, BMR Journal of Australian Geology & Geophysics, 1 (1976): 261-71.
  9. National Museum of Australia Collection File (Bureau of Mineral Resources).
  10. Ibid.
  11. A.B. Broughton Edge and T.H. Laby (eds), The Principles & Practice of Geophysical Prospecting. Being the Report of the Imperial Geophysical Experimental Survey, (Cambridge University Press, Cambridge, 1931): 1-8.
  12. Ibid: 146 & 360)
  13. Ibid: 150-52 & 172-73.
  14. Aerial, Geological and Geophysical Survey of Northern Australia, Report for Period ending 31 December 1939: 46 & 50-1; and, John Rayner to Denis Shephard, personal email dated 8 November 2006.
  15. Op cit. ref. 5: pp. 263-91 & 304-38; and, op.cit. ref. 4: pp. 61-246.
  16. National Museum of Australia Collection File (Bureau of Mineral Resources and Geoscience Australia 2)
  17. Louis Brown, Centennial History of the Carnegie Institution of Washington. Volume II.  The Department of Terrestrial Magnetism (Cambridge, 2004): 1-54.
  18. J.A., Fleming, ‘Two New Types of Magnetometers Made by the Department of Terrestrial Magnetism of the Carnegie Institution of Washington’, Terrestrial Magnetism and Atmospheric Electricity, xvi/1 (March 1911): 1-2; and, J.A. Fleming and J.A. Widmer, ‘Description of the CIW Combined Magnetometer and Earth-Inductor’, Terrestrial Magnetism and Atmospheric Electricity, 18/3 (September 1913): 105-10.
  19. Inventory card for magnetometer CIW-7, in Instrument and Equipment Records Series Three, Sub-Series 1: General Technical Documentation and Correspondence, 1892-1970 (Carnegie Institution of Washington, Department of Terrestrial Magnetism Archives, Washington); and, P.M. McGregor, ‘Australian Magnetic Observatories’, BMR Journal of Australian Geology and Geophysics, 4 (1979): 361-71.
  20. Inventory card for magnetometer CIW-16, in Instrument and Equipment Records Series Three, SubSeries 1: General Technical Documentation and Correspondence, 1892-1970. (Carnegie Institution of Washington, Department of Terrestrial Magnetism Archives, Washington).
  21. Inventory Card for magnetometer CIW-18, in Instrument and Equipment Records Series Three, SubSeries 1: General Technical Documentation and Correspondence, 1892-1970. (Carnegie Institution of Washington, Department of Terrestrial Magnetism Archives, Washington).
  22. L.A. Richardson, ‘On Magnetic Work in Australia, April 1936 to December 1944’, in W.F. Wallis and J.W. Green, Land and Ocean Magnetic Observations, 1927-1944, (Washington, 1947): 61-66.
  23. F. Jacka, Magnetic Observations at Heard, Kerguelen and Macquarie Islands, 1947-51, Bureau of Mineral Resources, Geology and Geophysics Records (Canberra, August 1953): 5 & 8; N.G. Chamberlain, Cocos Island Magnetic Survey, 1946, Bureau of Mineral Resources, Geology and Geophysics Records Number 124 (Canberra, 1960): 1: and, Bureau of Mineral Resources, Geology and Geophysics Geophysical Observatory Reports, 1960 to 1961.
  24. Charles Barton, ‘The Search for the South Magnetic Pole’, Preview, 95 (October 2001): 26- 7; and, Granville Alan Mawr, South by Northwest. The magnetic crusade and the contest for Antarctica, (Wakefield Press, Adelaide, 2006): 260-5.
  25. Op cit. ref. 5: 374-97; op.cit. ref. 4: 987-1015; and, Rocks to Riches: 76-81.
  26. National Museum of Australia Collection File (‘Bureau of Mineral Resources’).
  27. Op cit. ref. 5: 16-30 & 40-147; and, J Exploration Geophysics: 639-937.
  28. National Museum of Australia Collection File (‘Bureau of Mineral Resources’, ‘Geoscience Australia’, No 1 and Geoscience Australia, No 2).
  29. National Museum of Australia Collection File (‘Geoscience Australia’ No. 1).
  30. National Museum of Australia Collection File (‘Geoscience Australia’ No. 2).
  31. National Museum of Australia Collection File (‘Bureau of Mineral Resources’ and ‘Geoscience Australia’, No 2).
  32. Inventory Card for Dent chronometer 53862, in Instrument and Equipment Records Series Three, SubSeries 1: General Technical Documentation and Correspondence, 1892-1970 (Carnegie Institution of Washington, Department of Terrestrial Magnetism Archives, Washington).
  33. National Museum of Australia Collection File (‘Geoscience Australia’, No. 2).
  34. National Museum of Australia Collection File (‘Bureau of Mineral Resources’).
  35. National Museum of Australia Collection File (‘Bureau of Mineral Resources’).
  36. National Museum of Australia Collection File (‘Geoscience Australia’, No. 2).
  37. Op. cit. ref. 1: 243.