The whole question of Polynesian navigation is highly controversial. Dr. David Lewis's paper ‘Ara Moana: Stars of the Sea Road’, in the July issue of this journal, prompts me relate the story of Kau Moala in somewhat greater detail and to assess his achievements and motives, largely from his own account of his voyages.

Kau Moala was a Tongan Chief renowned for his epic feat of navigation which probably took place in the years just before 1800. The details come to us from a young English castaway named William Mariner, who spent several years in Tonga and knew Kau Moala personally. When Mariner got back to England his experiences were compiled by J. Martin and published by John Murray, London, in 1817. The work is generally known as ‘Mariner's Tonga’, the full title being An Account of the Natives of the Tonga Islands. The story of Kau Moala's famous Odyssey is given on pages 307–322 of volume I of the second edition, published in 1818. Mariner gives the Chief's name as Cow Mooaly.

The story starts with Kau Moala going from Tonga to Fiji to engage in some warlike adventures to enhance his prestige, as many another Tongan Chief had done before, and as several did later. After two years of fun and mischief he decided to return home, and set out in his large double canoe.

In Captain Wylie's note on ‘Radar as an anti-collision aid: the ultimate essentials in presentation’, masterly definition by an acknowledged expert aptly crowns the discussion which follows Commandant Oudet's paper on ‘Collisions and the Courts’ in the same issue of the Journal. It is interesting and gratifying to find in that discussion a suggestion by E. S. Calvert on manœuvres in close-quarter situations which recalls a similar proposal made by the French Institute at our first joint meeting held in London in 1957. It is that the manœuvre should be a turn of 2x° to starboard if a threat, an echo for example, is perceived x° forward of the port beam. This suggestion passed almost unnoticed at the time although it is mathematically sound if one assumes that the speed of the two vessels is the same.

The release of GNSS raw data on Android smartphones provides the potential for high-precision smartphone positioning using multi-constellation and multi-frequency signals. However, severe multipath and low observation quality in kinematic environments make double-differenced uncombined ambiguities difficult to resolve reliably. To address this, the paper proposes an improved wide-lane (WL) integer ambiguity resolution (IAR) method that combines integer rounding and the Least-Square AMBiguity Decorrelation Adjustment (LAMBDA) methods. The proposed method achieved fix rates of 57% to 70% in challenging environments, with an average improvement of 7 · 7% in horizontal positioning accuracy compared to the float solution. The traditional partial integer rounding method only improved accuracy by 1 · 1%.

Readers of Captain Cotter's paper under this title in the April 1976 issue of the Journal may be interested in some evidence that Dutch seamen in the seventeenth century were aware of this phenomenon of ship magnetism.

Abraham de Graaf in De seven Boecken van de Groote Zeevaert, published at Amsterdam in 1658, warns ships' officers taking bearings with the compass-that metal objects in their clothing can seriously deflect the compass, and mentions iron buttons and buckles. This was an important contemporary work on navigation and de Graaf was an examiner of officers of the Dutch East Indies Company from 1679 to 1714.

In this age of explosive expansion in nearly every aspect of human endeavour our ability to make accurate forecasts is becoming increasingly important. We cannot wait until we run out of oil to find a new source of energy. We cannot wait until we can't stand living on the earth to slow down the rate of pollution. We cannot wait until there is no room left to stand on dry land before we do something about birth rate. We must predict what is likely to happen as a result of trends and then find ways either to change the trends or protect ourselves from the consequences.

The regulations governing visual avoidance of collision in the air and the carriage of aircraft lights were originally based on marine practice and extended to include the third dimension in aviation. These regulations were established first by the International Convention for Air Navigation and finally by the International Civil Aviation Organization.

In planning a flight over polar regions, celestial navigation is of paramount importance: Loran and Consol coverage is doubtful and Gee chains non-existent; interpretation of the P.P.I. screen is hampered by lack of accurate survey and the camouflaging of coastlines by ice packs. Thus navigational accuracy and the amount of activity needed to maintain it depend largely on the foresight with which the flight is planned to render celestial information available.

Before considering in detail the instrumentation involved, it is necessary to establish first of all what is meant by microwave radiometry and mention briefly its possible applications. A radiometer is a device for measuring heat radiation and the title ‘Microwave Radiometry’ is a little surprising in that it implies heat radiation at microwave frequencies. In fact a consideration of the underlying physics shows that heat radiation and electrical thermal noise are indeed the same phenomenon, although their properties were investigated independently by physicists and electrical engineers. This concept is particularly valuable in microwave radiometry, where the electronic techniques are appropriate to ultrasensitive noise measurements, but the system applications are most easily visualized in terms of heat, or, more particularly, temperature.

The helicopter traffic over the North Sea is performed in uncontrolled airspace over international waters. The lack of radar coverage makes the establishment of controlled airspace difficult. The development of Automatic Dependent Surveillance (ADS) and use of satellite technology for Navigation, Communication and Surveillance (NCS) have made it possible to evaluate Modified Automatic Dependent Surveillance (M-ADS) as a basis for establishing controlled airspace over remote areas without radar coverage.

This paper describes how it was found possible to estimate the accuracy, under operational conditions, of navigators' wind-determinations by the 3-course drift method. This was done by studying the self-consistency of the set of three drifts logged by the navigator; the technique which was developed, using the size of the circle inscribed in the ‘triangle of error,’ can be used expeditiously by persons with no special training. This technique is applicable to other position line problems. Of the total inaccuracy of the winds found by the navigators, three quarters was contributed by the errors of observation of the drifts, and one quarter by the process of deriving the wind from the set of drifts, using the Dalton Computor.

The validity of the method was checked by comparing wind measurements by the 3-course drift method with the value obtained from Air Position Indicator readings taken in the course of practice bombing exercises; the accuracy of the latter value was also estimated from internal consistency. The check was satisfactory; and in particular, contrary to widely held belief, showed that the navigators did not systematically underestimate drift angles.

A general programme of work with the overall aim of reducing the incidence of collisions in the Dover Strait has been commissioned by the Marine Division, Department of Trade and Industry. As part of the programme the Operational Research Unit in DTI is developing mathematical models of traffic flow, using inputs of data provided from the surveys mounted by NPL and described in the paper by Johnson and Wheatley.

In view of the appeal for observations that has been issued by the Institute to assist in the determination of the accuracy of astronomical observations at sea, it may be of interest to navigators to recount some of the experiences of a hydrographic surveyor. Large regular surveys usually depend on geographical positions which are obtained on shore with accurate instruments. In cases where surveyors fix these positions with astrolabes, or occasionally theodolites, three observers will probably have taken observations of some thirty-two stars each. In the analysis, intercepts of the order of 4–6” are obtained, and the final position is probably accurate to about 1”. Some hydrographic surveying, such as a one-day search for a reported shoal out of sight of land, various minelaying and minesweeping operations out at sea, and the determination of oceanographical stations on long passages, however, demand ordinary sights taken in the normal way at sea. The value of the hydrographic operation may depend on the accuracy of these sights, and therefore the report on the operation generally attempts some assessment of their accuracy. Considerable care is taken to achieve accuracy and often the ship is stopped and the sights referred by range and bearing to a moored beacon, even in depths of 500 fathoms. Methods of determining the accuracy obtained may be by taut-wire runs from known points of land or taut-wire distances interconnecting several beacons. Failing, or in addition to, these methods, two to four observers' results may be compared, or Sun and star sights can be referred to the same beacon; even short tautwire or patent-log runs to well-defined and previously well-fixed fathom lines have been used.

In October this year an international conference on the revision of the International Regulations for Preventing Collisions at Sea will be held in London. A working party appointed by the Maritime Safety Committee of Imco, under the chairmanship of Captain A. C. Manson of the Department of Trade and Industry, has drawn up proposals for the revision of the present regulations. Captain Manson described these proposals to an open session of the Technical Committee held in London on 17 May 1972 with Captain D. A. G. Dickens, an Elder Brother of Trinity House, in the Chair. Introducing the subject the Chairman said that the Institute, through its Journal, the discussions it had promoted on previous occasions, and through the working party set up in 1970, had taken a significant part in forming opinion on the issues involved. In particular perhaps it had ventilated the suggestions that collision avoidance might better be based on positive manœuvring instructions rather than by simply apportioning responsibility. The long-term influence of these suggestions may well be considerable even though they might not in the event be reflected in the Rules now being proposed.

Few aspects of geography are more satisfying than to follow the progress of geographical discovery across the oceans from the documents that remain to us, and the careful work of many scholars allows us to find some of the excitement of the early voyages without much effort to ourselves. But geographical exploration was only the first phase, and during the past 300 years much effort has been spent in finding out something about the oceans themselves: as early as 1698 Halley sailed as far as S. 52° on a purely scientific voyage, returning with useful information about magnetic variation and the trade winds. The promoters of the scientific voyage of H.M.S. Challenger argued that the vast oceans lie scientifically unexplored, and we say much the same today; but much has been done and in its way it provides a story as interesting as that of geographical discovery.

It may be interesting to report some measurements of refraction which Professor A. N. Black and I made this winter. These were made on the setting Sun, and as the altitude of the observing station was 480.0 ft. it was possible to carry the observations down to the horizontal and, in fact, under clear conditions, to −20′.