In his paper ‘Two Mariner's Astrolabes’ (Journal, 9, 338) Dr. D. J. Price stated that hitherto only seven mariner's astrolabes had been found and the details published. He then described two more mariner's astrolabes, the Dundee astrolabe of 1555, discovered some months previously, and the Kronborg astrolabe of 1600, discovered in 1928.

Over 20 years ago, collision with high ground was identified as being the single most significant cause of fatalities among air travellers worldwide (Smith, 1968), and some human factors responsible were highlighted. The three factors most commonly found to be present during major civil aviation accidents were: (i) pilot's visual flight in instrument meterological conditions (IMC); (ii) navigational error by the crew and'; (iii) pilot's failure to react correctly to new circumstances resulting from air traffic control (ATC) instructions or advice – sometimes made in a language foreign to that of the aircrew. The latter factor will be tested here to see if it still applies to recent cases in the UK.

Migratory directions of birds have long been assumed to be at least partly ‘innate’ that is, genetically determined. In recent years much progress has been made toward understanding the genetic basis of several components of the orientation system. An important distinction has to be made between a bird's ‘knowledge’ of which direction to migrate, and its ability to use certain compass systems to find this intended direction. Both processes, establishing an intended direction and the subsequent compass orientation, have a partly genetic basis. The present review will be concerned only with the first of these processes, and the way it allows evolutionary changes of migratory routes to occur.

Lucretius, in the century before Christ, was by no means the first wise man to ponder and seek to explain the apparent mystery in this biblical citation, and he is but one of a great company of ancients whose recorded sayings are a delight to all who love the sea. We shall come back to Lucretius.

The purpose of this paper, which was presented at a joint meeting held in London with the Nautical Institute on 1 December 1983, is to give an account of the development of Dynamic Positioning from its inception to the present day, a simple description of the principles on which it works, and makes some predictions about its future.

Dynamic Positioning (DP) has been defined in various ways. For the purpose of this paper it will be denned as ‘The ability to hold a vessel in its desired position automatically without the use of physical restraints.’ Physical restraints are ropes, cables, anchors or any other items which connect the vessel to the bottom or to a fixed structure, be it an offshore installation or quay. The word ‘automatically’ means that manoeuvring control must be achieved without manual input.

Thomas Hariot's recently discovered manuscript ‘The Doctrine of Nauticall Triangles Compendious’ was the subject of a paper in this Journal by Professor Taylor and D. H. Sadler which poses but leaves unanswered the intriguing question of the method he employed in his computation. Sadler shows that the method depends on the fact that if sequences of meridional parts are in arithmetic progression the corresponding values of tan (45° − ½φ) will be in geometric progression. This is at once obvious from the modern formula for meridional parts:

But how did Hariot, writing before 1596, discover the relationship when neither logarithms nor the integral calculus had yet been invented; and was he able to prove it? It is the purpose of the present paper to supply a proof which requires neither logarithms nor the calculus. It is not claimed that this was necessarily the method that Hariot employed, although the manuscript reveals several points of similarity.

Orienteering is a navigational sport using large–scale maps (1: 15000) and a compass to locate, as quickly as possible, a series of control points in a pre–defined order. Orientation of self and map are fundamental skills in the sport of orienteering. The traditional teaching or coaching of this skill is based on a hierarchical model. This model introduces the concept of location of self by initial reference to landmarks, then routes linking individual landmarks followed by configurations of these landmarks and routes. This model quite clearly aligns with the hierarchical model of spatial reference systems suggested by Seigal & White (1975). However, it is proposed that the process-oriented model offered by Downs & Stea (1977) may be more appropriate to orienteering. The model is based on orientation and then develops through route choice, route monitoring and route recognition. Orienteering behaviour, which is based on using map and compass information to select and follow a novel route in a multi-choice route following task, appears to follow this model.

A better understanding of passenger movement in multi-modal transit situations is the major aim of this study. By using a novel Cooperative Positioning (CP) approach, algorithms can be generated which considerably increase the accuracy of person tracking. Smooth transit at stations is enabled, thus the total waiting time for routing at the traffic interchange is reduced. A Location-Based Services (LBS) user is guided by the service and located with the assistance of the whole user group. In addition to the technological developments, the acceptance and end-user needs are considered. End-users of such a service have the right to withdraw their consent for transferring location-based and other personal data at any time. They also receive clear and comprehensive information about when and why they reveal their personal data and location and its further use. In this paper, the concept is introduced followed by a comprehensive discussion of the suitable CP localisation techniques as well as an implementation strategy. Furthermore, ethical and usability aspects are discussed to ensure user-friendly results.

Scouring and sedimentation effects on the seabed induced by ship propellers during ship manoeuvring near harbour structures affect both structure stability and ship manoeuvring capabilities. This contribution proposes solutions at an operational level using the automatic identification system (AIS) and a bridge simulator. Two new alternative manoeuvres were designed and tested on a bridge simulator to obtain expected maximum scour depth and the results were compared with that of real manoeuvres (i) using mooring lines, and (ii) with tug assistance. A total of 42 test scenarios combining several manoeuvres and meteorological conditions were reproduced. Results confirmed a clear reduction in erosion depth with the alternative manoeuvres, with total reduction when using the tugboat. The presented methodology can be very useful to port authorities to prevent the effects of ship erosion on harbour infrastructures.

This paper reports on a new navigation algorithm for fixed-wing Unmanned Aerial Vehicles (UAVs) to bridge Global Position System (GPS) outages, based on a common navigation system configuration. The ground velocity is obtained from wind-compensated airspeed, and a centripetal force model is introduced to estimate the motion acceleration. Compensated by this acceleration, the gravity vector can be extracted from the accelerometer measurement. Finally, fusing the information of the ground velocity, magnetic heading, barometric height, and gravity vector, the Integrated Navigation System (INS) is reconstructed, and an Extended Kalman Filter (EKF) is used to estimate INS errors. Hardware-in-loop simulation results show that compared with INS-only solutions, the proposed method effectively resists long-term drift of INS errors and significantly improves the accuracy for dynamic navigation during GPS outages.

The objective of this study was to design and evaluate new means of complying to time constraints by presenting aircraft target taxi speeds on a head-up display (HUD). Four different HUD presentations were iteratively developed from paper sketches into digital prototypes. Each HUD presentation reflected different levels of information presentation. A subsequent evaluation included 32 pilots, with varying flight experience, in usability tests. The participants subjectively assessed which information was most useful to comply with time constraints. The assessment was based on six themes including information, workload, situational awareness, stress, support and usability. The evaluation consisted of computer-simulated taxi-runs, self-assessments and statistical analysis. Information provided by a graphical vertical tape descriptive/predictive HUD presentation, including alpha-numerical information redundancy, was rated most useful. Differences between novice and expert pilots can be resolved by incorporating combinations of graphics and alpha-numeric presentations. The findings can be applied for further studies of combining navigational and time-keeping HUD support during taxi.

The number of ships involved in collisions in Japanese waters, excluding collisions with fixed or floating objects, increased rapidly in the 1960s, as can be seen in the statistics of the Marine Accidents Inquiry Commission: 1578 in 1955, 3604 in 1960, 6043 in 1965 and 7642 in 1970, while the increase in average tonnage resulted in numerous serious accidents. To cope with this situation, the Maritime Traffic Safety Law (MTSL) was enacted in 1973, defining eleven traffic routes in congested waters. The Tokyo Bay Traffic Advisory Centre was established in 1975 and started operation in 1977. The trend in the number of traffic accidents requiring assistance shows the effect of traffic management in reducing the number of accidents.

This paper, which was presented at an Ordinary Meeting of the Institute held in London on 19 November 1980 with the President in the Chair, first outlines the arguments for simulators for use in training and research. The technical problems encountered in simulating ship behaviour are discussed, and the various engineering approaches which have been used for actual simulator construction are described. An account is given of experience to date with ship simulators in the UK, and the future prospects for marine application of simulator methods are discussed.

In 1966, in a note in the Forum entitled ‘Longitude without Time’, Francis Chichester described a method of determining longitude, or time (G.M.T.), from observations of the altitude of the Moon; and this gave rise to considerable interest. Recently a number of papers, of varying standards, have been published on the same subject; some, ignoring fundamental principles, have described techniques that are erroneous or misleading. Those principles, which have been well known for centuries, are here restated. In general, techniques of observation, calculation and plotting are not given; they are matters for the choice of the individual.

A symposium was held in London on 6 December 1982 under aegis of the Institute with the traffic management fuel conservation working group to discuss meteorological forecasting and its application in terms of fuel saving. The chairman was J. C. Morrall, Chief Scientist of the Civil Aviation working group. In the United States, the work of Dr R. Steinberg of NASA on the penalties of imperfect forecasts and possible benefits from an improvement was of considerable interest. V. W. Attwooll and L. Bennett of the CAA had also studied penalties from North Atlantic forecasts. Part of the UK civil avionics programme was concerned with the forecast of winds applied in particular to 4-D time-slot following; this was. described by R. C. Rawlings of RAE Bedford. Mr C. Flood, of the Meteorological Office, finally presented prospects for improved forecasts.

In a recent issue of Nature Sir Charles Goodeve gave an illuminating account of the value of operational research in war and described how, in peacetime, similar methods were being applied to problems of rail and road traffic. It is significant that he was unable to give examples of similar investigations into the flow of air traffic.

In all forms of navigation a distinction can be made between the two processes of finding out what the present position is and finding out what direction to go in to reach a given destination. On land the former process becomes the more important of the two because the constraints of natural ground features or of artificial obstacles often make a preset course impossible, as a motor drive along English country lanes shows so well. The destination will often be reached from an entirely unforeseen direction.

This paper was presented at a meeting of the Bristol Channel Branch of the Institute i n Cardiff on 28 April 1976.

The work and life of John Thomas Towson falls neatly within the professional group so aptly styled by the late Professor E. G. R. Taylor as the Mathematical Practitioners. Born in Devonport in 1804, Towson was educated at Stoke Classical School in that town and on leaving school followed his father's trade as a chronometer maker. When only 22 years of age Towson invented a device for banking the balance of a chronometer and his invention was communicated to the Society of Arts in 1826.

The voyage of Luis Baez de Torres in 1606 resulted in the discovery of the whole southern coast of New Guinea, and of the existence of a strait between Australia and New Guinea. These great geographical results were hidden from the world, and even from the Spanish realms, so completely that sufficient data on the voyage for general study has not been available until recently. The very brief report by Torres to the King was not found, copied, translated and published until 1806, exactly 200 years after the voyage; the four charts made during the voyage were published in 1878, and the long narrative by Prado was found by chance in London, translated, and published in 1929. Hundreds of documents of secondary importance were collated and published in 1965, but owing to the habit of historical writers of using older ‘authorities’ instead of original sources, many fallacies regarding the voyage have been perpetuated to the present day, and no doubt will be in the future. The present writer, working from photostat copies of the original reports and charts, has plotted the track of Torres' two vessels from island to island and point to point by interpreting the records, by navigational deduction and from a long experience of navigating ships through the very waters traversed by Torres. He has also made sketch surveys of uncharted areas and has studied the various rare charts, maps and globes compiled by different cartographers between 161 3 and 1700 from the three or four coastal charts drawn by Prado but missing from the archives since soon after the voyage.

The principal conclusion of this study is that Torres used Endeavour Strait to get clear of the innumerable islands and reefs which blocked his course to the west and was therefore in sight of the Australian coast for many days, a finding contested by several previous writers.

This paper formed the 1990 Anderson Memorial Lecture and was presented to the Bristol Channel Branch on 22 February. In developing his theme, George King concentrated very much on the characters of the navigators concerned with six extraordinary exploits, but without losing sight of the navigation itself. The following version is necessarily much abridged and the editor has reluctantly omitted the detail of fascinating accounts of the expedition commissioned by Thomas Jefferson to explore the American West, the epic open boat voyage by Ernest Shackleton in the Antarctic in 1916, the first solo air crossing of the Atlantic by Charles Lindbergh in 1927, and the spectacularly successful Apollo 11 mission in 1969. The full text of George King's meticulously researched and brilliantly written paper is available to members from the Institute, price £3.