bluuebunny/crossref_metadata_2025 huggingface dataset:
Marine Radar Automatic Plotter Display Philosophy
Authors: Wylie F. J.
Published: January 2010

The object of any kind of marine radar plot when ships are in fog is to synthetize as much data on the current traffic situation as affects or will affect the safety of own ship and so to produce a plan picture of the area around the ship and the vessels moving on it, more or less as it would appear to the eye in clear weather. The plot will be expected to show, not only the current position of each ‘target’ vessel, but also the expected forward movement of each and the risk of collision which this involves.

The word synthetize is used because it so completely implies the building up of separate elements of information into a whole; in this case, a continually changing whole. The word whole is also worth emphasizing, because only if the situation is so presented can the mariner appreciate the form which its development is taking both between own ship and those target ships which present a direct threat and between target vessels whose mutual evasive manœuvres may indirectly endanger own ship. The needed synthesis cannot be attained unless the predicted future positions of target ships are coordinated in time, so that the relative positions at the future time may be compared with the current relative positions.
II.—Modern Display Techniques
Authors: Humphries D. E.
Published: January 2010

Modern digital computers are well known to be extremely fast and accurate, but another attribute which is even more vital in the role of nerve centre to a modern nav./attack system is flexibility. The ground-based computer that carries out a different task every day of the week is now normal, but even in a military aircraft the computer is called upon to fulfil several roles: on the ground analysis and diagnosis, in the air navigation and weapons delivery, and often as flight director computer if the situation demands. Because of its characteristics of carrying out the computations serially in a central processor, a single decision point can alter the whole characteristics of the program; a single switch could make the computer carry out a fault diagnostic program or the navigation/attack program. By the action of one switch the meaning of every other switch and display can be altered. It is this characteristic above all that calls for special displays if full advantage is to be taken of the flexibility in the main computer interface.
Underwater Arctic Navigation
Authors: Cestone Joseph A. , St. George Emery
Published: January 2010

The objective of this paper is to show that an underwater navigation system can be developed that is technically and economically feasible and of high reliability for long distance under-ice operation. Recent advances in underwater navigation for cruise, exploration and search and rescue operations are considered and applied to the current interest in Arctic waters, where mineral prospecting and oil transportation are potentially important.

The paper was read at a meeting of the Institute held in London on 27 February 1974 with F. A. Haworth in the Chair. Mr. Cestone is from the Naval Ships Systems Command of the United States Department of the Navy; Mr. St. George from the Charles Stark Draper Laboratory of the Massachusetts Institute of Technology.
Through the Proper Channels
Authors: Best K. H.
Published: January 2010

This paper, based on a presidential address given to the British Section, Société des Ingénieurs Civils de France on 11 January 1974, examines the state of sea transport today and proposes a European Maritime Agreement along the lines of the Chicago convention for Civil Air Transport.

The following definitions may be agreed.

Channels all natural or artificial beds of rivers, estuaries or other bodies of water, or a body of water joining two seas, for example the Channel joining the North Sea with the Atlantic Ocean. The word also means ways of access or communications and methods of conveying nonmaterial things, such as in radio and radar systems.

Proper means fit, suitable, efficient and safe; a secondary meaning is correct according to rule and accepted custom.
The Requirements for Astronomical Navigation
Authors: Parker J. B.
Published: January 2010

In all sciences, the experimenter is constantly seeking to improve both the accuracy of his observations and the speed with which they can be obtained. He wishes, further, to use the minimum of basic equipment, and to obtain the maximum simplicity in collecting his results. Unfortunately, these factors frequently act in opposite senses: an expensive apparatus, for example, may be required to collect accurate data quickly. In certain fields, it is even worth while deliberately to sacrifice accuracy in order to gain advantage both in speed and simplicity. Thus, in astronomical navigation, it may be possible to simplify sight reduction, to cut down on the bulk of tables carried in the air, and to reduce the time taken for observation and reduction of a sight. The penalty will be a loss in accuracy, but, provided this is not reduced beyond a certain level, it may well be worth while. A review of the requirements for air navigation, and an examination of the problems of position finding by the stars against these requirements may lead to some conclusions as to whether an advantage is to be obtained by simplifying the methods.
A New Method of Observation and Reduction
Authors: Genty Robert
Published: January 2010

The method proposed consists in measuring by means of a specially designed sextant the altitude and azimuth of a star simultaneously and using these two quantities with the declination to solve the astronomical spherical triangle. In this way, both the latitude and, by means of certain simple additions and subtractions in terms of the local hour angle which is found directly, the longitude are determined.
The Instrumental Ideal
Authors: Bastien A. J.
Published: January 2010

If astronomical navigation can be made to give its results in as simple a manner and as quickly as do the modern electronic systems, then clearly it can provide an aid whose usefulness will remain undisputed. The aim, then, should be to develop a system of astro-navigation which will give an immediate and continuous reading of, for instance, latitude and longitude; and it seems quite possible at the moment to envisage the nature of such a system. Its realization is perhaps another matter; and this may take time that perhaps the development of other systems will render ill-spent.

The ideas put forward in this paper are only concerned with the fundamentals of what, in the writer's opinion, is a possible solution to the problem; they are also not all new.
The Use of Radar in the Ice-breaker Service
Authors: Larsson Hugo
Published: January 2010

For the purpose of comparing results with the two wavelengths, 3 cm. and 10 cm., generally used in navigational radar, the Defence Forces Research Institute, in collaboration with the Swedish Admiralty, the Royal Pilot Service and the Marine Cartographical Institute, carried out systematic researches and experiments under various conditions, in view of the special meteorological and navigational circumstances prevailing in Swedish waters. Two radar equipments covering these wave-bands were obtained from the Research Institute and installed on board the marine survey ship Gustav Av Klint during the summer of 1947. A separate report has been issued on the results obtained during the summer months.
Heeling and Pitching Error Correction without local Readjustment
Authors: O'Beirne T. H.
Published: January 2010

This paper first gives a brief account of the deviation theory applicable to magnetic compasses and a unified theoretical treatment of the principal heeling-error and pitching-error effects. Consequences of symmetry in soft-iron correctors are then considered, and a system of six equal soft-iron spheres at equal distances along three mutually perpendicular axes is shown to have no effect at the compass position, any diametral pair thus having a complete negative counterpart in the remaining four.

This leads to the deduction of the possibility of a simple form of corrector system in which soft-iron correctors remove those parts of the principal inclination errors which are due to induced magnetism. If the remaining part due to permanent magnetism is assumed to be removed by vertical magnets in the usual manner, the correctors when once adjusted would then require no readjustment on change of locality, in distinction from all known correctors at present in use or in course of manufacture, which require continual readjustment in these conditions.
A New Shore-based Radar Equipment
Authors: Fennessy E.
Published: January 2010

Presented at a meeting of the Institute held at the Royal Geographical Society on 15 June 1951.

Shore-based radar stations to supervise or assist the navigation of ships have now been employed for at least a decade. Such stations were more extensively used during the war than they have been since, principally because there had to be large convoy movements along heavily mined coastlines under conditions when, because of wartime limitations, many of the more conventional navigational aids were not available. The most important wartime development in the use of radar in this direction was undoubtedly the introduction of high power centimetric equipment and the plan position indicator. Since the war the use of shore-based radar to assist navigation of merchant shipping has been extremely limited and the only outstanding installation of this type is the Liverpool Harbour Supervision System, which was brought into service in 1948. This system has now been in operation for three years and has provided a great deal of information and has created a world-wide interest.
A New Wrinkle in Astro-navigation
Authors: de Aquino F. Radler
Published: January 2010

Over thirty-seven years have passed since the writer published his ‘Wrinkles in Plane Chart Methods’, explaining the value and use of his then new ‘Protractor Diagram’ and ‘Graduated Triangle’ for plotting lines of position on squared paper. A figure showed the simplicity of the solution, overcoming the difficulty of the use of different units for the differences of latitude and longitude.

It is now proposed to present a further ‘wrinkle’ to facilitate the use in navigation of six prominent equatorial stars, particularlyMintaka(δ Orionis) which is only 2o′ south of the equator, and practically a fixed star since its annual (precessional) variation in declination is only 2″·67. It is one of the three stars of Orion's belt and its magnitude is 2·5, slightly fainter thanPolaris.
Unification of the Air Almanac and the American Air Almanac
Authors: Clemence G. M. , Sadler D. H.
Published: January 2010

As from 1953 theAir Almanacand theAmerican Air Almanacwill become a single publication, under the title of theAir Almanac. It will be produced jointly by H.M. Nautical Almanac Office of the Royal Greenwich Observatory, Herstmonceux, and the Nautical Almanac Office of the U.S. Naval Observatory in Washington, to meet the general requirements for air navigation in the United Kingdom, the United States and Canada. TheAir Almanacwill be printed and published separately in the United Kingdom and the United States but the two publications will otherwise be identical.
Radar as an Aid to Air Navigation in the Arctic
Authors: Greenaway K. R.
Published: January 2010

Summary of a paper presented to the Canadian Institute of Navigation at a meeting held in Montreal on 22 September 1950.

In 1946 and 1947 a great deal was learned about scope interpretation and the use of search radar as an aid to air navigation in the Canadian Arctic. New techniques, differing from those used during the war, when search radar was considered primarily as an aid to bombing and for pin-pointing, were developed and a great deal of information on interpreting the radar presentation of topography at different seasons was obtained. The use of search radar for navigation in the Arctic is described in this paper, which also gives information on the probable appearance of topographical detail on the display at different times of the year.
Observations of the Green Flash
Authors: Simmons R. E. G.
Published: January 2010

A Letter published in theJournal(Vol. IV, No. 2, p. 211) from Captain Brett Hilder refers to the use of the phenomenon known as the green flash for obtaining longitude at sea, and an editorial comment on the letter suggests that accurate descriptions of what has actually been observed at different times at sea might be of value to meteorologists. The following notes, though they contain no reference to using the observations for navigational purposes, may be of some interest as they are the result of a great many observations of the phenomenon.

Numerous reports on observations of the green flash have been published in meteorological publications where, as a general rule, it is accepted that it is only seen under conditions of extreme visibility and clearness of the atmosphere. From numerous personal observations it has been ascertained that this is in fact not so, and that the green flash can be observed under conditions of extreme cloudiness, haze and humidity so long as the horizon is visible at the time of rising or setting of the heavenly body. Another factor affecting the actual sighting of the green flash is the intensity of light emanated by the body, for the flash is of very weak intensity when compared to the normal brilliance of the body observed.
Air Navigation and the New Institute
Authors: Slessor John
Published: January 2010

The foundation of the Institute of Navigation has given satisfaction to many, but perhaps to none more than the shade of the great man who in 1673 inaugurated on the basis of the old charitable institution of Christ's Hospital ‘a nursery of children to be educated in Mathematics for the particular use and service of navigation’. That science has made some strides since Samuel Pepys's day. But no one who has read Arthur Bryant's fascinating study of the Great Secretary of the Admiralty under the Restoration can doubt that old Samuel would have been well abreast, if not ahead, of all developments, especially as they affected the King's Fighting Services. His comments on the subject after his experience of the Great Storm of 1684 have a very realistic and modern ring about them: ‘We are very solicitous in our disputes and opinions touching our draughts and log lines and things’ he wrote ‘when we are at a loss for our ways … but as soon as ever we see land all difference is forgot, or any desire of recording the truth, but on the contrary, everybody endeavours to make himself be thought to have been in the right, and not thinking also that they should ever come to the same loss in the same place again. Hence it comes that the science of navigation lies so long without more improvement’. How true, and how curious that it should have been more than 260 years before the foundation of this Institute, under a president one of whose predecessors was called in by Pepys in 1686 to defend against unjust criticism a treatise on the science of navigation.
Altitude Corrections for Coriolis and Other Accelerations
Authors: Sadler D. H.
Published: January 2010

Some apology, or at least an adequate excuse, is needed for resurrecting a theoretical treatment of the effect of coriolis acceleration on observations of altitude made with a bubble sextant. Such an excuse is provided by the recent publication by Dr. J. J. Green of an article suggesting that the correction table (Z-correction) given in both the British and AmericanAir Almanacs(and in many other Air Almanacs) is incomplete. In a reasoned letter to the Editor ofNavigation, Dr. G. M. Clemence, Director of the American Nautical Almanac Office, has given a simple and straightforward explanation of the two separate and distinct causes for the deviation of the zenith as indicated by the bubble of a bubble sextant; and he has further justified the present practice adopted in the almanacs. Considerable interest has, however, been aroused and it seems opportune to give a previously unpublished general derivation of the theoretical correction, together with a brief discussion of the difficulties of practical application.
Consol
Authors: Jessell A. H.
Published: January 2010

Consol is the name now given to a navigational aid developed by the Germans during the war. A Consol beacon broadcasts on a medium frequency a pattern of dots and dashes, and by listening to this pattern on an ordinary ship or aircraft wireless receiver a navigator can determine his bearing from the beacon with a much greater accuracy than is possible with a D/F loop. The accuracy of the bearings obtained depends on the bearing of the observer from the beacon; it is greatest along a line called the normal of the beacon and decreases until it is zero along a line at right angles to the normal. The useful coverage with the existing type of beacon is about 280° out of 360°. With such a beacon the range over the North Atlantic is about 1200 n.m. by day and 1700 n.m. by night; the probable error on the normal is by day about° and by night (at ranges greater than 500 n.m.) about ½°.
IV—The Application of Pressure Pattern Flying to Civil Transoceanic Routes
Authors: Pike E. W.
Published: January 2010

Since the inauguration of the B.O.A.C. Return Ferry Service, the principles of pressure pattern flying have been followed on the North Atlantic as regards flight planning. In co-operation with the forecaster the practice developed of working out a number of flight plans to achieve the shortest possible flight time, and eventually it became possible to select the most favourable route with a reasonable degree of precision.

The advent of the radar altimeter furthered development of the pressure position line theory which I believe was first propounded by R.A.E., Farnborough, and has since been elaborately garnished and enthusiastically tested by our American friends during recent years. The words ‘altimetry’ and ‘aerologation’ have been added to our generally common language to cover flight techniques that might perhaps be more simply described as ‘pressure comparison navigation.’
What is the Ideal Air Map?
Authors: Chichester Francis
Published: January 2010

Why the perfect air map does not exist. Air maps have been struggling for years to reach perfection; most of them fall far short of it for three main reasons:

(1) Maps are designed by highly skilled specialists who, however, do not generally know from first hand experience what the practical requirements are. They rely on hearing of these from practical airmen.

(2) The better the practical men are at map reading the less able they are to put into words how they set about it and what is required for the ideal air map.

(3) Map production is extremely expensive in time, work and materials with the result that map makers are loath to scrap a map once made, if it will ‘do,’ even though they realise it might be improved.
II—Report of the Cot Division
Authors: Macintosh G. M.
Published: January 2010

Following extensive demonstrations of radio-aids to navigation, telecommunication equipments and associated electronic developments, in U.K. from 9 to 26 September, in U.S.A. from 7 to 26 October and in Canada from 28 to 29 October 1946, the first session of a Special Radio Technical Division of PIGAO was held in Montreal from 30 October to 23 November 1946. The final report of this first session has been published as an ICAO Document, No. 2553/COT/26, and the portions dealing with radio-aids to navigation will be of interest to members of the Institute. The report cannot be regarded as ‘a formal ICAO action’ since it has not been adopted by the Interim Council, and from the U.K. point of view there have been a number of reservations in matters of detail.
The Requirement for Precise Navigation
Authors: Bell G. E.
Published: January 2010

Before considering in any detail the importance of precise navigation to air traffic control, or attempting to define the word ‘precise’ in this context, it seems desirable to go back to fundamentals and consider certain essential characteristics of a volume of traffic flowing between individual pairs of airports in a system comprising a large number of such airports, randomly distributed and heavily loaded.
Preventive Navigation
Authors: Barnett D.
Published: January 2010

The high concentration of aircraft near aerodromes, with consequent collision risk is well known. It is at present necessary, in poor visibility, to guarantee the indispensable commodity of safety by the sacrifice of schedule regularity and fuel economy. So long as this is the case, the problem of terminal navigation and control must be regarded as one still demanding a satisfactory solution.
What the Pilot Wants
Authors: Bennett D. C. T.
Published: January 2010

In daylight and in good visibility no mandatory flying control is either necessary or desirable. The basic task of air traffic control is therefore (a) to give information so as to expedite landings and take-offs in good flying conditions and (b) to give information and instructions in blind flying conditions or at night.
Marine Position Fixing Systems in Use Today
Authors: Hogben H. E.
Published: January 2010

Before the war the only radio navigational aids in current use by shipping were direction finding systems, operating in the medium frequency band of the radio spectrum.

During the war, not only were many new types of position fixing systems evolved, but radar techniques were also developed, thus making available a wide range of new facilities of potential use both to ships of many different categories and to port and harbour authorities for the supervision of marine traffic.
Use of Direction Finding at Sea
Authors: Best F. P.
Published: January 2010

Direction finding is the oldest, simplest, and probably most reliable radio aid yet offered to the mariner. In some ways it may be likened to a magnetic compass and, if its range is very much smaller, it has the inestimable advantage over a compass of giving bearings on a very large number of stations instead of one only. It is the only navigational aid, other than radar, in which the performance is controlled by the shipborne installation and is not subject to technical failures which may occur on land-based transmitters.
The Adoption of Decca as an Aid to Navigation at Sea
Authors: Fennessy E.
Published: January 2010

The determination of a ship's position by means of radio observations from fixed shore transmitters has now been practised for a considerable period of time, but up to the outbreak of the last war the accuracy obtained from the conventional direction finding systems then in use was only sufficient to provide a general estimate of position suitable for off-shore navigation in waters where the ship's position need be known only to within a mile or two. It was not until, under the pressure of wartime requirements, the modern range of radio aids to marine navigation were produced that means were provided by which the mariner was enabled to determine his position with an accuracy comparable with that of the best visual fixing but with the great advantage that these observations could be made in all conditions of visibility and weather. At the end of the last war there were three systems of outstanding merit available: Gee, Loran and Decca. All three systems, as is well known, employ a combination of master and slave stations, the transmissions of which provide radio position lines capable of accurate calculation and plotting on navigational charts.
An Instantaneous Fix on Two Bodies
Authors: Nightingale P. L.
Published: January 2010

The need for the rapid reduction of astro-sights has been constantly stressed for use in high speed aircraft outside radio coverage. The method described here is a combination of precomputation of altitudes and graphical representation of intercept from a given position. By this method a fix can be plotted at the instant of time for which it has been precomputed.
The Reduction of Consol Bearings for Plotting
Authors: Simmons R. E. G.
Published: January 2010

The use of Consol at long ranges in ships is hampered by the lack of facilities for accurate plotting. Of necessity ocean charts (scale 1:1,000,000 to 1:12,000,000) are used; and on these it is not practicable to plot running fixes, lay off position lines from celestial observations or to compare a succession of cross bearings with any degree of accuracy.

When Consol bearings can be plotted on a large scale chart and used in conjunction with other position lines, such as Marcq. St. Hilaire, lines of soundings, m.f./d.f., &c, they are of assistance in defining an observed position; this is especially so in conditions of poor visibility, such as prevail in the approaches to the British Isles and in the North Atlantic.
The Double Altitude Problem: A Historical Note
Authors: May W. E.
Published: January 2010

The publication of the paper Astro-fix by Computation by Oliver C. Collins in the April number of the Journal serves as a reminder that the observation for the determination of the latitude from two altitudes, usually known as the double altitude problem, is one of some celebrity in the history of navigation.

The following notes on the subject may be of some interest although they are far from complete, having been compiled from such books as happened to be readily available, and can only be considered as an introduction to the subject.
Radar and Ice
Authors: Le Page L. S. , Milwright A. L. P.
Published: January 2010

The need for investigations into the detection of ice by radar became apparent when merchant ships started reporting that ice formations were inconsistent radar targets, and that ships relying upon radar to navigate through ice areas could, in some circumstances, have their safety endangered.

Certain investigations, notably those carried out by the U.S. Coast-guard Service and by the Swedish Defence Research Institute, resulted in the publication of a great deal of useful descriptive information but it was not accompanied by measurements of the actual echoing power of ice targets. With the object of carrying the matter further, a special enquiry was made during the 1950 and 1951 North Atlantic ice seasons, when a number of British ships plying North Atlantic routes completed questionnaires in which the sizes and shapes of ice formations were noted together with their radar detection ranges. This enquiry was instituted by the Operational Research Group in the Marine (Navigational Aids) Division of the British Ministry of Transport, which later analysed the data collected and issued a report. There were, however, certain limitations in this investigation. For example, the performance of the radars was not known, because of their inherent differences and the fact that none of the ships carried instruments, such as echo-boxes, for checking performance; further, propagation conditions at the time of making the observations were not established.
The Development of Tidal Theory
Authors: Doodson A. T.
Published: January 2010

The influence of the tides on navigation requires no emphasis to those who have had the responsibility of navigating ships in tidal waters, but there will be few who will have entirely escaped some of the difficulties which tidal problems may bring, especially in unfamiliar waters. Most navigators will therefore have some sympathy for the experience of Alexander and his armies on the way to the mouth of the Indus. Their experience in the Mediterranean had not prepared them for what they had to suffer when they passed into tidal waters.
Navigating Ashore
Authors: Bagnold R. A.
Published: January 2010

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.
Navigation and Hydrography
Authors: Day A.
Published: January 2010

Ever since you did me the honour of making me your President it has been fairly inevitable that the subject of today's Address should connect the work of hydrographers with that of navigators. It has also been clear to me that I should not try to emulate too closely the two distinguished men of science who have been my predecessors in office. Their Addresses have contemplated, and given us useful thoughts for, the future; mine will be more easily developed from the standpoint of the user, and will attempt to see how accepted principles and methods are in fact being applied for the navigator's purposes.
The Use of Pressure Pattern Flying by Trans-Canada Airline
Authors: Peel R.
Published: January 2010

Upper winds over the North Atlantic are strong and their circulation is complex; until aircraft speeds are considerably increased, therefore, the choice of a route which will take the maximum advantage of the wind distribution consistent with safety can make a worthwhile contribution to operating economy. This paper describes some of the methods adopted by Trans-Canada Airline on its North Atlantic route to achieve this end.
A Dead Reckoning Computer
Authors: Blom-Bakke A.
Published: January 2010

The procedures of dead reckoning require a number of different steps, amongst which are distance measurement, angle measurement, construction of straight-line tracks, the solution of the vector triangle and the process of multiplication and division. The navigator's plotting and dead reckoning instruments are designed to meet these needs. The ruler serves both as a distance-measuring scale and as a means of drawing a straight line track; the protractor measures angles; the dividers measure distances and the Dalton computer serves both as a method of solving the vector triangle and as a circular slide rule for multiplication and division.
A Record of Radar Performance in Ice Conditions
Authors: Perry R. E.
Published: January 2010

In order to gain first-hand experience of the conditions encountered by the growing number of vessels plying the Hudson Bay route, Mr. R. E. Perry, an engineer of the Decca Radar Company recently made a passage to Port Churchill in the S.S. North Anglia.

During the course of this passage a complete radar log was kept by Mr. Perry. This log is noteworthy not only for the many reports of the radar detection of various types of ice but also for the detail and completeness of the information recorded.
Vancouver Shore Radar Station
Authors: Lancaster G.
Published: January 2010

A list of existing and projected shore radar installations to aid merchant shipping was given as an Appendix to Mr. Le Page's paper on the requirements for port radar (Vol. V, p. 295), where unfortunately First Narrows Bridge was described as spanning the Fraser River. In making this correction, Commander Lancaster, the Harbour Master at Vancouver, has sent the following description of the installation, which provides a useful supplement to Mr. Le Page's paper.
A First Attempt to Obtain a Fix from Transit
Authors: Nicholson W.
Published: January 2010

The Transit system of navigation is based upon the observation, by radio, of artificial satellites. The basis of the method is to determine the line-of-sight velocity of the satellite towards, or away from, the observer at various times as the satellite moves across the sky. With a knowledge of the corresponding orbital positions and velocities of the satellite, the observations can be used to determine, without ambiguity, the position of the observer.
Ionospheric Research through Transit
Authors: Golton E.
Published: January 2010

It has already been explained that one has to correct for the effect of the ionosphere upon the doppler shift in order to track the Transit satellites with sufficient accuracy. At the Radio Research Station, Slough, the converse problem is being investigated; we are looking at the effect of the ionosphere upon the Transit satellite signals in order to find out about the ionosphere itself. In fact the doppler correction term is directly related to one of the quantities of major interest, the electron content of the ionosphere. This is the number of electrons in a unit column up to the satellite height. We are interested in the daily, seasonal and solar variation of this quantity.
Siting a Harbour Radar Equipment
Authors: Lumsden G. J. A.
Published: January 2010

Captain Lumsden's paper was written for the convention held in Düsseldorf on 16, 17 and 18 May 1961 (Journal, 14, 480). It describes the siting of harbour radar equipment from the point of view of giving warning of approaching ships to the shore authorities, giving navigational assistance to shipping, and port surveillance. In most cases the choice of site for the aerials and displays will have to be a compromise with these three uses of shore radar in mind.

The three main elements of a harbour radar are the scanner, which must be sited to survey the area of interest, with the transceiver close by to avoid waveguide losses, and the displays which may be required in a room close to the scanner or in a room distant from it.
A Proposed System to Produce True Motion in Relative Displays
Authors: Manley B. W.
Published: January 2010

A system is proposed which would be capable of adding information concerning the true motion of objects, to the normal relative display. The method requires the use of two Tenicon storage tubes (ME 1260).

The use of marine radar has not eliminated collisions at sea. The reasons for this failure are generally associated with limitations in interpreting the available information, rather than in the equipment itself. One particular problem is the assessment of the time, course and speed of a ship from the information presented on a radar display, which is relative to the observer. It is possible to calculate this information, but the direct presentation of a true course on the display would be advantageous. A solution is to modify the final PPI display so that the centre of the scan, normally fixed at the centre of the cathoderay tube, is displaced continuously at a velocity corresponding to the observer. The true speed and course of a ship can therefore be assessed from the track built up from echoes received during successive scans.
The Navigation and Control of Supersonic Aircraft
Authors: Polhemus William L.
Published: January 2010

This paper, which was presented at an Ordinary Meeting of the Institute held in London on 17 November 1961, discusses aspects of high-speed, high-altitude navigation which will have a bearing on the selection of a navigation system and control philosophy for supersonic transports. The effects of certain separation criteria on systems accuracy are described, as are meteorological factors bearing on operation of the aircraft. Estimated performance capabilities which relate to traffic control and navigation are described. An analysis is offered of the effects of particular system accuracies on the selection of components of a navigation system and, finally, an integrated system is described, with arguments presented for certain levels of redundancy, reliability and automation.
Notes on Heavy Weather in the Atlantic 1960 and North Sea 1961
Authors: Lewis David H.
Published: January 2010

The following notes, from one of the contestants in the single-handed transatlantic race 1960, will be of great interest to a number of people concerned with wind and weather observations and the performance of small boats in heavy weather. Dr. Lewis's track in 1960 was by the great circle from Plymouth to New York, from New York up to St. John's, Newfoundland, and then back across the Atlantic to Lerwick in the Shetlands.
A Survey of Five Years' Progress in Marine Radar
Authors: Wylie F. J.
Published: January 2010

In describing progress in the development of a functional equipment, it would be quite normal to begin by defining the technical targets at which the engineers are aiming and the operational uses to which it will be put. In the case of marine radar, however, it is not possible to be precise in either of these matters. It might be said that the ultimate target is to make port, coastal and open sea work as safe and straightforward in poor visibility as in good; or, put in another way, to replace direct human vision in poor visibility and to improve upon it at any time when the distance of targets is to be measured with accuracy.
A Norse Bearing-Dial?
Authors: Taylor E. G. , May W. E. , Motzo R. B. , Lethbridge T. C.
Published: January 2010

In the July number of the Journal Captain C. V. Sølver described the discovery, by the Danish archaeologist Dr. C. L. Vebæk, in Greenland in the summer of 1951, of what was believed to have been part of an early bearing-dial. The object, which was dated by the archaeologists at about the year 1200, was one-half of an oak disk the outer rim of which was carved in such a way as to lead Captain Sølver to the conclusion that the complete disk was divided into thirty-two points or directions. Captain Sølver's paper was illustrated by a photograph of the fragment discovered and of his reconstruction of a similar bearing-dial.

Professor Taylor comments below on Captain Sølver's paper, and on the more general question of a Norse bearing-dial which it raised. Comment on the problem invited from a number of members and others is also given.
Low-Altitude Astro Sights
Authors: Nightingale P. L.
Published: January 2010

On 13 flights at different heights and outside air temperatures a total of 127 low-altitude sights were taken of the Sun, Moon and planets. The sights were taken with a Kollsman periscopic sextant which uses an illuminated graticule as a datum. Hughes' Tables were used for the calculations and the corrections for refraction taken from the table published in Navigation.
III—The Problems of Forecasting
Authors: Kirk T. H.
Published: January 2010

The pilot or navigator expects the forecaster to supply him with: (a) forecasts of wind and temperature; and (b) forecasts of meteorological hazards, e.g. turbulence, icing. The increase of operating height and range of modern aircraft make it increasingly difficult to maintain a high standard of accuracy of forecasts.
Practical Navigation over the North Atlantic
Authors: Willis D. C.
Published: January 2010

This paper, which gives a useful description of the procedures used by one transatlantic operator, was presented in Montreal at a meeting of the Canadian Institute of Navigation held on 7 December 1955. Many of the methods discussed are referred to in the preceding three papers.

1. Any discussion of today's long-range navigational practices and problems seems to lead inevitably to pressure-pattern and jet-stream flying. The reason might well be that during recent years the more important practical developments appear to have concerned techniques rather than aids or instruments.
M.O.U.S.E.
Authors: Porter J. G.
Published: January 2010

Although no details of the proposed artificial satellites are yet available, the idea is by no means new, and it seems likely that any successful experiment of this kind must follow the plans already outlined by Professor S. F. Singer of Maryland University. At the Astronautical Conference at Zürich in 1953 he gave details of a small spherical satellite, weighing only 100 lb., which would revolve about the Earth in a period of 90 minutes at a height of 190 miles above the surface. In collaboration with Arthur C. Clarke and A. V. Cleaver of the British Interplanetary Society, Singer called this instrument MOUSE (Minimum Orbital Unmanned Satellite Earth) and proposed that it should be launched as a three-stage rocket with an initial all-up weight of about 35,000 lb., and a thrust of 65,000 lb., which is very little different from the performance of the V2 rocket. The first step would take the rocket vertically through the lower atmosphere and then turn over to begin the inclined part of its flight; the second stage would come into action when the first had burned out, and complete the climb to give the correct altitude and direction of motion. The third stage would merely give sufficient boost to attain the required speed, which is about 17,400 m.p.h. At the moment of cut-out (controlled from the ground) the nose tip would open and release the satellite. This would take the form of a sphere, about three feet in diameter, spinning so as to maintain a constant orientation, and packed with instruments. The spin axis, parallel to the Earth's surface and perpendicular to the direction of motion, would point to the Sun, so that one half of the sphere would be strongly heated by the Sun's rays, and the other hemisphere would be extremely cold. Power would be obtained from a new type of solar battery, and the readings of the instruments would be radioed continuously to Earth.
Two Mariner's Astrolabes
Authors: Price Derek J.
Published: January 2010

The first scientific instrument to be designed specifically for use at sea was the mariner's astrolabe. The cross-staff or Jacob's staff had been used by astronomers since the Middle Ages, and the magnetic compass used by navigators had long been familiar as an aid to land travel, a means of setting portable sundials, and in the east, a device for divination.
The Use of Bisectors
Authors: Davies Alan
Published: January 2010

Lieutenant-Commander Bini's interesting paper on the use of bisectors shows the trap open to the believer in the 3-line fix and goes on to show the M.P.P. when four lines are used. However, as the ideal for the four lines is to have each at 90° apart, an error in either one or two lines provides the observer with an ellipse for the M.P.P. and is for practical purposes but a variation of the 3-line cocked hat circle of M.P.P. and little appears to have been gained by the working of the fourth line.
S-Diagrams for Solving Problems in Astronomical Navigation
Authors: Smart W. M.
Published: January 2010

The method described in Schütte's paper is very ingenious and evidently simple in its application; it depends on solving two pairs of equations of identical forms (in terms of different variables) by simple inspection of diagrams constructed in accordance with the first pair of equations. In his paper the author states, with reference to a figure and without proof, the two pairs of equations referred to. It is obvious that the fourth of Schiitte's equations (p. 310) is inconsistent with the figure and with the example he gives on the determination of altitude and ‘azimuth’ (pp. 312, 313). The trouble arises partly from misconception as to the use of the term azimuth. The method deserves a more detailed explanation of the derivation of the formulae and their application.
Comparison between two Decca Chains
Authors: Freiesleben H. C.
Published: January 2010

Summary of a paper presented at a meeting of the Auschuss für Funkortung at Essen on 28 February 1956.

In any investigation of the accuracy of Decca fixes it is necessary to distinguish between systematic and random errors. Investigations are generally based on a comparison between a Decca fix and a fix obtained by some other method; because of the high accuracy of Decca the other method must in practice be a terrestrial fix. The investigation can be made by comparing the decometer readings with values calculated for the true position; or the Decca position may be compared directly with the true position. The first way gives the differences of the Decca observations in terms of percentages of a lane, and the second shows immediately the errors of the Decca fix. The second method includes the uncertainty caused by the siting of the Decca stations, that is by the angle of intersection of the Decca hyperbolae. The second method will be of more direct use to practical navigators while on the first will be based considerations of a theoretical and strictly technical nature.
Gyro/Grid Navigation
Authors: Kendall E. C.
Published: January 2010

In June 1955, Canadian Pacific Airlines inaugurated a regular scheduled service between Vancouver and Amsterdam via the polar route. The Company had a wealth of northern experience which was of immense operational value on the polar route. In addition to its overseas services, C.P.A. has operated regular flights for many years to far northern parts of Canada and some of the group of companies which amalgamated to form C.P.A. in 1942 had arctic experience dating from the days when commercial aviation was in its infancy. One aspect of navigational experience which has helped its navigators on many occasions has been the map reading talents of the former bush pilots who show an astonishing ability to locate themselves visually over country which is mostly water, and where one lake looks much like every other lake.
Some Navigational Techniques for Use with Marine Radar
Authors: Mackay I. S. S.
Published: January 2010

The parallel cursor and disc. In the Royal Navy manœuvring problems are normally worked out on the Battenburg Course Indicator which gives a mechanical solution of the speed/distance triangle (Fig. 1). A similar device for direct use on the PPI face can be made by engraving parallel lines on the rotatable PPI mask and attaching two perspex vector arms to the centre. Although developed primarily for manœuvring purposes this idea can be put to several purely navigational uses and from it have sprung two valuable adjuncts to the PPI: the parallel cursor and the fixed plotting surface (or disc).
The Plane Sailings
Authors: Cotter C. H.
Published: January 2010

If a ‘sailing’ is defined as a means of finding by calculation, tables or construction, either: (a) the course and distance from one place to another, or (b) the position of arrival after making a given course and distance from a given position, then what is commonly known as ‘plane sailing’ is not in this sense, a sailing at all. ‘Plane’ or ‘Plain’ sailing according to modern as well as early usage involves the arguments, distance, d. lat., departuie and course angle, and in order to solve the problems (a) or (b), d. long., and either meridional d. lat. or ‘middle’ (not ‘mean’) latitude must enter the solution.
Visual Navigation in Enclosed Waters
Authors: Mitchell J. B.
Published: January 2010

Most shipmasters making a tortuous passage through a strait or among reefs and islands, after a long passage on one course in a vessel equipped only with magnetic compasses, are worried out of all proportion to the hazards of the manœuvre by reason of not knowing in all certainty what compass errors will pertain on widely different courses. Of course there is the Azimuth Record Book, but the last time similar courses were used could have been in the other hemisphere or under different conditions of trim, &c.

Given time, weather conditions and other suitable opportunity a prudent master will have conducted a swing to ascertain the errors before approaching the stretch of dangerous water. This may not be possible and, again, he knows in his mind that azimuths taken under these circumstances, with little time to waste, do not always conform to the later findings.
Marine Casualties in the Pacific Islands and their Economic Consequences
Authors: Couper A. D.
Published: January 2010

The economic development of archipelagic territories is intimately linked with shipping. In the archipelagoes of the Pacific small vessels connect many islands with one or two port towns. These towns are entrepôts for cargoes of consumer goods, petroleum and timber, and they are transhipment points for copra and fresh produce coming in from the island hinterlands. Towns, such as Suva, Lautoka, Apia, Nuku'alofa, also serve as local markets and educational, social and medical centres for the people of the outer islands.

In Fiji there are about 90 inhabited islands outside Viti Levu. The villages and estates in the outer islands all focus in some way on the port of Suva. There are many economic and social problems in the islands and these are made more acute by high freight rates and the unreliability of some services. But most of the shipping operators would be hard put to reduce freight rates or to improve the quality of their ships and services. One reason for this is the burden of marine accidents.