bluuebunny/crossref_metadata_2025 huggingface dataset:
Astrofix and Rectofix Tables
Authors: Sadler D. H.
Published: January 2010

Through the interest of Mr. S. M. Burton, I have recently seen for the first time the comprehensive proposals for ‘astrofix tables’, compiled by Gilbert F. Cunningham, B.A., Ph.D. (then Staff Navigator, R.A.F.V.R.) and submitted to the Empire Air Navigation School at Shawbury in May 1945. Dr. Cunningham, a member of the Institute since 1948, is no longer actively engaged in the field of navigation, and he has therefore agreed to allow me to describe in the Journal those features of these proposals that are both new and interesting
Direct Communication with Radar Identified Shipping
Authors: Arkieson I.
Published: January 2010

When radar is used at sea as an aid to collision avoidance, the necessary information has to be obtained by maintaining a plot, which, however, can only offer the average course and speed over a passed time. It is not a reliable prediction of future actions, so that to make too long an extrapolation from a plot is hazardous. It might in some circumstances be better if a ship could be called up by radio and asked her intentions, though this requires first a knowledge of her identity and call sign.

This paper outlines a system of communication that would make it possible to call a ship (fitted with the necessary receiving equipment) initially located only by range and bearing, to obtain the identity of the ship and establish courses, speed and intended actions, and if necessary, radio call signs and calling frequencies. The messages passed by a ship would be recorded automatically. It is proposed that the system should have an operating range of 15 miles, though this does not represent a limit to the range possible. There are objections perhaps to trying to get out of a mutilateral situation of danger by bilateral agreements, and at least one school of thought would hold that the danger is likely to be increased by relying on communication. Nevertheless the system described here holds considerable interest and might, as the author suggests, serve other purposes at sea.
Brain Function in High-speed Navigation
Authors: Gooddy William
Published: January 2010

Disasters result from the breakdown of navigational faculties. Those concerned with the ‘practical’ aspects of navigation naturally assume a standard and infinitely flexible nervous system by which the individual can adjust to the stresses created by great speeds in the absence of habitual sense information. This paper outlines the nervous basis of adjustment to environment (personal navigation), the forms of breakdown in disease, and the nature of hallucinations. Some forms of disturbing experiences likely to be felt in modern navigation are predicted and explained. Such problems are seen as integral matters of aviation planning, design and practice.

‘The main aim … is to enable interested persons with quite different backgrounds of knowledge and experience, to come together and consider collectively a subject of common interest from their various standpoints.’

(A. M. A. Majendie, ‘The Significance of Blunders’, this Journal, 12, 28.)
The Grand Topography of the Universe
Authors: Taylor E. G. R.
Published: January 2010

The two books considered here, despite the romantic title of the larger and more ambitious one, are complementary both in subject matter and in interest. In The Sleepwalkers, Arthur Koestler offers us a highly un-conventional, and in detail controversial, history of man's picture of the Cosmos. But he brings it to a close with the Newtonian synthesis since this afforded a simple scheme satisfying to mathematician and layman alike. This, he claims, is the picture still accepted by the majority today, and as regards the ‘man in the street’ and the school textbook he may be correct. But during the present century there has been an accelerating series of amazing astronomical discoveries which in their earlier stages were excitingly presented to the reading public by Eddington and Jeans. Last year Professor Lovell, in the Reith Lectures, brought listeners up to date, and dealt briefly with the individual man's place within the vast dimensions now revealed.
Air and Sea Tests of the Dectra Radio-navigation System
Authors: Powell Claud
Published: January 2010

The object of this paper is to summarize the results of air and sea trials that have been obtained in the first two years' operation of the experimental Dectra chain in the North Atlantic area. Reference is also made to observations at fixed monitor stations, and briefly to the Dectra data link for air-to-ground transmission of the Dectra fix.

Dectra, which stands for ‘Decca Track and Range’, is a long-range position-fixing system derived from the Decca Navigator. Early in 1957 two of the three transmitting stations forming a Dectra chain designed to cover the North Atlantic air routes were put into operation and flight tests began in March of that year; in the following October, air trials started using all three transmissions. Various tests at sea have also been carried out, although on a much less extensive scale than those in the air.
Clarifying the Rules of the Road
Authors: Hilder Brett
Published: January 2010

The primary Rule of the Road at Sea is to keep to the right in practically all cases. The single exception which comes to mind in regard to fully manœuvrable vessels under power is overtaking in a narrow channel, when the overtaking vessel should keep to port and take the risk of meeting any on-coming traffic, like the working rule on the roads ashore. The alternate use of true direction as a frame of reference at sea, suggested by Lieutenant-Commander N. L. Fendig, U.S.C.G. in this Journal (October 1958) would lead us from simplicity into confusion. The same confusion would apply ashore if the roads were marked with compass courses, and vehicles were to give way to eastern traffic, which would sometimes be on the right, and sometimes on the left hand.

The notes by Commander Clissold, R.N.R., under the above heading in the same Journal, are both sensible and workable, but hardly stimulating in nature, as they deal with tedious detail like the rules themselves, without calling for a new outlook. I find the basic Rule of the Road beautifully clear compared with the pages of exceptions and details, most of which show no correlation with each other, or to the basic rules. While I believe that the present rules are the best possible for fully manœuvrable powered vessels, those concerning vessels of limited movement are complicated with confused detail lacking a clear cut system based on relative manœuvrability.
The Pelorus
Authors: May W. E.
Published: January 2010

In 1854 a bearing plate was invented by Matthew Curling Friend and William Browning to facilitate the taking of bearings where the compass was inconveniently situated for observation.

Friend was born at Ramsgate on 21 January 1792 and entered the Royal Navy as a First Class Volunteer at the age of 14½. Though continuously employed in ships, which carried him to Africa, the West and East Indies and to China, he does not seem to have caught the eye of his superiors for he did not obtain his lieutenant's commission until February 1815. He subsequently served in the Bucephalus, 32, one of the ships which escorted Napoleon Bonaparte to his exile at St. Helena. While on board the Bellerophon in Plymouth Sound, waiting for the great powers to decide his fate, the fallen emperor used to exhibit himself daily at the gangway and the populace came out in boats and thronged round to see him. On the day that he was transferred to the Northumberland for his yoyage there was an even greater press of boats than usual and one was capsized, throwing its occupants into the water.
Transverse Navigation: An Alternative to the Grid System
Authors: Fox W. A. W.
Published: January 2010

In the second issue of the Journal a system of grid navigation was described. This system warrants serious consideration because of its application to polar navigation and because it offers a means of simplifying navigation in high-performance single-seater aircraft of long range. These aircraft are going to present extreme difficulties, particularly in naval aviation, where fixing facilities and pilotage are limited.
Some Aspects of Flight Planning in Civil Aviation
Authors: Williams E. Brook
Published: January 2010

Prior to the outbreak of war in 1939, flight planning procedure was not generally practised in civil aviation operations except in a few outstanding cases. Such operations as the Imperial Airways transatlantic flying boat flights called for the careful compilation of a flight plan in order that an indication of the flight time could be obtained. Since the range of these boats did not provide for any very great reserve, the flight plan was obviously an essential part of the preparation for the flight. In the case of a few shorter range operations, flight planning was also carried out to a certain extent: one operator, for instance, adopted a procedure whereby departures and arrivals were made to a schedule, and the aircraft operated so as to comply with this schedule. The increase in the length of route stages and the need for more technical operation of aircraft from the economic point of view indicated the need for more general use of serious flight planning, and it is now well established that flight planning is essential to the safe and efficient operation of flights of all kinds.
Errors in Observed Altitudes
Authors: Worlledge J. P. G.
Published: January 2010

The calculation and publication of the errors in measured altitudes due to tilt of the sextant serve a useful purpose in impressing users more strongly with the need for care than does the unbacked advice to rock the sextant always given in the text-books, and also in indicating that carelessness carries greater penalties the greater the altitude. The work once done is done for ever, so we may as well get the sum right.
Operational Factors and Operational Yields
Authors: Parker E. , Le Page L. S.
Published: January 2010

It is helpful at an exhibition to have a catalogue of the items on view. As this symposium is in effect a display of the operational aspects of marine radar, it may be of value in this paper to attempt to catalogue these aspects. They can be divided into two groups as follows:

A. The aspects that determine the effectiveness of marine radar (the siting of the scanner and the operating policy followed, for example). These we propose to call the OPERATIONAL FACTORS.

B. The benefits obtainable from marine radar (i.e. those aspects that may be said to measure its effectiveness—the time and worry saved, for example). For these we suggest the term OPERATIONAL YIELDS.
The Fitting and Use of Navigational Radar: An Analysis of Some Experience Gained
Authors: Whitfield H. R. , Harrison A. , Pope T. J.
Published: January 2010

The basic principles of the detection and location of objects by radar are now widely known, and the performance requirements of a marine radar equipment have already been covered by the British Ministry of Transport specification. This paper describes and analyses operational experience gained in fitting and in operating a number of equipments manufactured to this specification.
Some Navigational Experience with Marine Radar
Authors: Puckle O. S.
Published: January 2010

The flagship of the General Steam Navigation Company, s.s. Seamew (Captain T. C. Stone), 1209 tons, has recently completed various trips on which data relating to the use of her navigational radar have been noted. The data collected bear on many problems of presentation and practice and are described in this paper.
On Increasing the Radar Echoing Characteristics of Buoys and Small Boats
Authors: Milwright A. L. P.
Published: January 2010

During a cruise by H.M.S. Fleetwood in Scandinavian waters last autumn the opportunity was taken of measuring the intensity of echoes received from the sea, for various wave heights. These echoes are commonly known as sea clutter and the object of the measurements was primarily to provide data on which to design suitable anti-clutter circuits for use in civil marine radars. The results obtained, however, show the need for increasing the radar echoing characteristics of small navigational marks and small boats.
Charts and Chart Matching Devices
Authors: Satow P. G.
Published: January 2010

No satisfactory means of securing positive identification of individual radar echoes in congested waters has yet been devised, although many ingenious suggestions have at different times been put forward. These ideas include systems for providing a special identification signal from selected buoys, or alternatively for a considerable increase in the number of buoys and their arrangement in groups in definite patterns at strategic points so that they may be easily picked out on the ship's P.P.I.
The Accuracy of Wind Finding by the 3-Course Drift Method: A Statistical Analysis
Authors: Stansfield R. G.
Published: January 2010

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.
Notes on Astro-Navigation in Polar Regions
Authors: Zaccheo F. E.
Published: January 2010

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.
The Navigator's Problem in Aerial Survey
Authors: Saffery John
Published: January 2010

The three principal tasks of the navigator on an aerial survey expedition are to get to the survey base, to recognize and define the area to be surveyed, and to fly across this area in parallel flight lines so as to photograph it adequately and economically. During the survey, the courses flown, height, speed and the time of day chosen are all influenced by the demands of the camera and of the photogrammetric machines which will produce the map from the air photographs. For this reason it is essential that the navigator, on whose competence during the survey the results will largely depend, should have a proper understanding of photogrammetry, photography and of the basic principles of ground survey. It is true that the crew will include a photographer and that the photogrammetric aspects of the operation will have been considered beforehand by those responsible for briefing the crew; nevertheless there are always unexpected problems which arise in the field and every aspect of the undertaking must be at the fingertips of the navigator who, in the final count, is responsible for the photographic coverage of the area.
Radar Leading Patterns
Authors: Parker E.
Published: January 2010

In the discussion on Blind Estuary Pilotage held by the Institute on 18 June 1948, the writer (see Journal, Vol. 2, No. 1, p. 60) put forward the suggestion that the well-known principle of radar shadowing could be used to provide accurate leading patterns for ships navigating straight channels or harbour entrances. Two possible patterns of this sort are illustrated in Figs. 1 and 2.

The pattern shown in Fig. 1 uses six ‘targets’ and two ‘screens’ and would be suitable for any channel wider than about 200 yards. The channel illustrated is meant to be about 200 yards wide, and the configuration of the pattern—though not the dimensions of the targets and screens—is drawn to the same scale.
The Earth's Magnetic Field
Authors: Jones Harold Spencer
Published: January 2010

The Institute has now completed two years of its existence. The papers which have been read before it during these two years have covered a wide range of subjects and have served to emphasize the many ramifications of the science of navigation. Because of the high speed of modern aircraft, air navigation presents more problems and of greater variety than surface navigation, but even on the problems of surface navigation there has been ample scope for a wide range of discussion. The Institute has taken a prominent part in the discussion of the proposals for the revision of the Abridged Nautical Almanac. It might with some reason have been supposed that there was nothing more to be said on the methods of reducing astro-sights and determining position at sea. The problem is perfectly straightforward and there is a limit to the number of different ways in which the spherical triangle can be solved. But the essential basic data can be presented in a variety of ways, while there are many possible methods of presenting tables for the solution of the spherical triangle. The decision to use Greenwich hour angle instead of right ascension in the Abridged Nautical Almanac has followed its adoption in the Air Almanac; the revised Almanac will have an entirely different format from the present, while the methods of reducing sights must be correspondingly modified.
Admiralty Chart 2649: A Chart Adapted for use with Radar
Authors: Satow P. G.
Published: January 2010

Practical experience in radar-assisted marine navigation has shown that the closer one is to the general land areas, navigational seamarks, &c, the easier position fixing from radar information becomes, although some particularly congested and confined waters provide exceptions to this rule. There are usually large numbers of more suitable targets available at the closer ranges, and increased ease of identification results from objects being closer to the observer. The latter effect, of course, arises from initially knowing one's position more accurately, and this in turn is based on the shorter ranges at which bearings and/or ranges are being taken.
The use of two Decca chains to obtain accurate fixes at long ranges
Authors: Cottle A. R.
Published: January 2010

This paper deals with the improvement to be gained by using position lines from two Decca chains to obtain a fix in areas where a single chain fix is liable to extensive errors.

Recently The Decca Navigator Company, with the cooperation of the Admiralty, undertook a series of trials between Scotland and southern Norway, using the English and Danish chains of stations outside the normally used coverage of either chain. The results obtained were highly satisfactory and an account of them is given in this paper.
Vertical Navigation Requirements for S.S.T.
Authors: Davies W. P. , Jeffery C. B. , Polhemus W. L. , Ursel L. V.
Published: January 2010

This paper presents some preliminary conclusions about navigation requirements for supersonic aircraft, in particular those which relate to management of the aircraft along its vertical flight path.

The conclusions are based on an evaluation of some 200 computer-simulated flights of the mach 2 Concorde. The simulation contained models of real-world atmospheres for polar, temperate and tropical latitudes taken from actual upper-air observations and integrated over selected great circle routes used in the study.

The computer programme was designed to permit three kinds of flight schedule: operation according to the manufacturer's recommended mach-altitude profile, operation with respect to a set of arbitrary A.T.C. profiles, and operation along an optimum-energy profile. The results permit us to suggest objectively, performance capabilities, airspace requirements, and limiting conditions which are essential factors in specifying the vertical requirements.
Air Traffic Control Procedures in a Parallel Track System
Authors: Villiers J. , de Barbeyrac J.
Published: January 2010

In this paper M. Villiers, Ingénieur en Chef de la navigation aerienne, and M. de Barbeyrac, of the Société d'Etudes des Systèmes d'Automation, discuss the application of a satellite monitoring system to A.T.C. procedures.

The paper first discusses control of lateral separation under the headings of present navigation accuracy over the North Atlantic and by a satellite monitoring system. It goes on to discuss control of longitudinal separation with and without monitoring, and finally discusses intervention procedures and aids.

The writers conclude that it is possible with a mathematical model to establish a general relationship between the performance of aircraft navigation systems and a monitoring system on the one hand, and the lateral and longitudinal separation of aircraft and the mode of A.T.C. action on the other. From this relationship the number of A.T.C. interventions can be computed and it appears that the reduction of separations resulting from a satellite monitoring system will fit such a system to the forecast air traffic beyond 1975. In addition, the requirement for voice communication, specific to A.T.C., would be extremely limited. The paper was presented to the S.S.T. Working Group, sponsored jointly by the French, German and British Institutes of Navigation.
The Operation of Hovercraft
Authors: Colquhoun L. R.
Published: January 2010

In this paper, which was presented to the Institute at an Ordinary Meeting in London on Wednesday, 14 February, the Managing Director and Chief Operator of Hoverlloyd describes his company's experiences in operating hovercraft across the Channel and its hopes with regard to the 250-passenger SR.N4. The characteristics of hovercraft and their implications for navigation are described.

Cross-Channel operations in SR.N6 hovercraft. In 1965 the Swedish Lloyd and Swedish American shipping groups placed an order for two SR.N4 hovercraft for introduction to the cross-channel route in 1968 and 1969. As a prelude to this service, an order was placed for two SR.N6 machines with which the parent companies intended to operate a pilot service between Ramsgate and Calais during the summer months of 1966 and 1967. These craft were delivered in the spring of 1966 and have now completed two years' activity, not only in the cross-channel field but in all spheres of commercial hovercraft activity.
Synoptic Ice Maps of the Meteorological Office
Authors: Tunnell G. A.
Published: January 2010

For a considerable time fishing vessels, merchant ships, long-range forecasters and oceanographers have needed up-to-date sea ice information. This paper describes how the heterogeneous mass of ice information combined with the very thorough climatic analysis now available has been used to produce for the first time an up-to-date picture of the entire distribution of ice in the Polar Basin and areas adjacent to the Atlantic Ocean.

For over a century a function of the Marine Division of the Meteorological Office has been the recording of Arctic and Antarctic sea ice, particularly since the Titanic disaster. However, the comprehensive hemispherical ice maps produced internationally have been several years in arrears. Ice information supplied to ships was therefore usually based on average conditions which suffice for planning well ahead or on long-range weather forecasts where it is necessary to follow ice development closely. It was decided in 1959 to organize a synoptic ice map with up-to-date ice and sea temperature information. Ice being more conservative than the weather, a map produced every ten days has proved to be sufficient.
Collisions in the River Scheldt
Authors: Netherlands Pilots' Association
Published: January 2010

On 30 March 1966, Captain A. Wepster, of the Holland-America Line, presented a paper to the Institution on collisions in Western European rivers. Through its publication in the Journal it had considerable impact on opinion abroad and in particular in the Netherlands where it became popularly known in nautical circles as the Wepster Report.

The Netherlands Pilots’ Association invited its nautical committee for the areas most concerned to investigate the findings of Wepster's paper and it is their report which is presented here.

The Wepster Report is a general discussion of the dangers and problems of navigation on the five main navigable rivers of Western Europe. It attempts a critical investigation into the causes of the decline of safety on these rivers and a good deal of attention is paid to the working methods of pilots and of the various institutions charged with organizing river traffic. Captain Wepster concludes his lecture with the remark: ‘… it is now to be hoped that others will throw some light upon it from another angle.’
Operational Research into Marine Traffic and Collisions
Authors: Beattie J. H.
Published: January 2010

There is an urgent need, both at international and national level, for more operational research into marine traffic and the associated collision casualties. At the present time marine traffic research is in its infancy and official analysis of collision is on a national basis with few attempts to correlate the two together and on an international basis. Without this basic information and research on the traffic and accident pattern, it will not be possible to plan effectively to reduce the high cost of collision casualties to ships' operators and to make the necessary improvements in safety over the next decade. This decade will see increasing carriage of dangerous cargoes in bulk, a continual large increase in the number of pleasure boats and the current trend of increasing numbers of merchant ships, fishing and other work-boats will probably continue. Due to this large increase and the trend to mammoth ships, the effective amount of sea space is being rapidly reduced and traffic control is inevitable in some areas.
What an Inertial Navigator Consists of
Authors: Bell Frank Coffman
Published: January 2010

Mr. J.G. Carr and Sq.-Leader D. Scott, R.A.F., have devoted sections two, three and four of a total of 21, and a few other remarks here and there in their excellent paper, ‘The testing of airborne inertial navigation systems’ (Journal, 20, 405), to the above title as an exposition ‘first necessary’ to their main purpose, limiting themselves to ‘the types of system of which we have practical experience’. They do not otherwise identify these types explicitly, but do include them among the ‘many ways of mechanizing this concept', viz., ‘The feature which is common to all inertial navigators is the measurement of acceleration of the vehicle by measuring [and in effect they add also “or metering”] the force required to constrain a proof-mass carried in the vehicle to move with it,’ and from this deducing velocity and position of the vehicle. This statement seems well put to me and quite sound, but in the fourth paragraph of Section 4, which includes ‘Fig. 1. A Schuler tuned inertial navigator’, they imply that at least their types, if not all inertial navigators, are based also on ‘Schuler tuning [so named] after the discoverer of the principle', and here I do not follow them. (I note in passing that the by-line of Schuler's 1923 paper, Physik. Zeitschr. XXIV, 344–50, spells his name without the umlaut used consistently by them.)
The Schuler Pendulum and Inertial Navigation
Authors: Stratton A.
Published: January 2010

F. C. Bell in his contribution raises most interesting philosophical questions. In commenting on them, I will refer to a recent translation (Navigation U.S.A., 14, 26) of Schuler's paper and use the same notation.

The impossibility of distinguishing by any physical measurement between a gravitational force and the inertial reaction force of an accelerating frame of reference is fundamental. In Fig. 1 our observer in an enclosed laboratory is observing the compression of a linear spring supporting a ‘proof mass’ m (he knows the natural uncompressed length of the spring).
The Search for Minerve
Authors: Pasquay J.
Published: January 2010

During the morning of 27 January 1968 the submarineMinervewas on exercise south of Cape Sicie. She was due to return to her base, Toulon, in the evening. Her last-known position was that fixed by a Breguet Atlantic aircraft on the same day at 0735. The last communication between this aircraft (then returning to base) and the submarine was at 0755.
Reversal of the Traffic Flow in the Dover Strait
Authors: Oudet L.
Published: January 2010

Some publicity has recently been given to a new plan proposed by Trinity House and the Honourable Company of Master Mariners for the separation of traffic in the Dover Strait. This would reverse the direction of flow established by Imco in 1967 according to which the main streams of traffic between the Channel and the North Sea keep to the right.

The authors of the scheme suggest that the number of collisions in the Sandettié-West Hinder area has increased dangerously since 1967 because of an unforeseen increase in the size, draught and speed of ships. Their aim is to prevent, in this area, crossings between traffic coming out of the Scheldt and traffic bound for Rotterdam, Germany, Scandinavia and the Baltic.
Spherical Triangles with Integral-degree Parts
Authors: Sadler D. H.
Published: January 2010

In certain esoteric mathematical and computing circles there is, or used to be before the advent of the electronic computer, an interest in near-integral solutions of incommensurable problems. Apart from aesthetic considerations such solutions can have valuable applications in the checking of methods of computation; this is the excuse for the following note.

The investigation from which it arises was itself a by-product. As part of the British contribution to the newSight Reduction Tables for Marine Navigation(H.O. 229 in U.S.A.; H.D. 605, in the United Kingdom) it was necessary to examine carefully each of the approximately 20 million figures in the six volumes; although the setting was computer-controlled and numerically checked, only visual examination could detect indistinct or broken figures. Such examination is extremely arduous and calls for great powers of concentration if its purpose is not to be wasted.
The Collision Problem and Manœuvring by Stages
Authors: García-Frías J.
Published: January 2010

When the danger of collision between vessels occurs, the proper interpretation of radar information will indicate that, with respect to the manœuvring rules, any avoiding action should always be positive. However, it is well known that radar information is not always properly interpreted. Misinterpretation may cause a situation to be assessed as ambiguous. This, in turn, may produce disagreement, on both vessels, about how the rules should be correctly applied. To solve this difficulty, some authors propose communication between the vessels. Others think the avoiding action of any vessel should automatically be such that the sight line rotates in the anti-clockwise direction. (The latter suggestion results in a port-to-port passing whilst the vessels cross with a port bearing from the aspect of the overtaking ship.) Complications may arise from either proposal.
The ‘Universal’ Sea and Air Navigation Tables and the a and b Almanac
Authors: de Aquino F. Radler
Published: January 2010

The position of a point on the surface will then be expressed by two spherical coordinates: namely, ist, the distance of the point from the primitive circle measured on a secondary; 2nd, the distance intercepted on the primitive circle between this secondary and some given point of the primitive circle assumed as the origin of coordinates.—William Chauvenet,Manual of Spherical and Practical Astronomy(1896).

On 16 May 1870, exactly eighty years before this paper was written, Lord Kelvin, then Sir William Thomson, worked out an epoch-making example of how to find the hour angle and azimuth of a heavenly body by inspection, in order to facilitate the use of Captain Thomas Sumner's method at sea. His work was published one year later in theProceedings of the Royal Society, and in it he describes a page of his new Tables for Facilitating Sumner's Method at Sea. These tables, comprising nine pages, were made public on 11 November 1875 and were published in London in May of the following year; from them have been derived all modern navigation tables based on right-angled spherical triangles. Kelvin then used, for the first time, Greenwich hour angle in arc and assumed latitudes and longitudes. (The writer has himself used G.H.A. in arc since 1902 and assumed positions since 1908.)
Dead Reckoning by Surface Current Observation
Authors: von Arx William S.
Published: January 2010

Recently an electromagnetic method for measuring the velocities of ocean currents for oceanographic purposes has been shown to be reliable enough for the observed velocity of the surface current to be taken into account in dead reckoning navigation in the open ocean. A preliminary test of the electromagnetic method as a navigational aid was made in 1949 on one cruise covering a distance of 1000 miles across the Gulf Stream and back. A total of 52 miles of lateral drift was corrected to produce a straight line of travel through the observed currents, and this correction enabled the ship to return to within 2 miles of the starting point. Seven less formal experiments performed in 1950 indicate that ordinarily, on straight-away courses, the lateral drift component caused by currents can be measured and corrected with the expectation that the undetected drift will be less than 1 percent of the distance travelled.
I—Special Problems in Polar Regions
Authors: Moore J. D. D.
Published: January 2010

The three basic problems of navigation are determination of position, definition of direction, and steering the direction required. In polar regions, all these problems are affected either by the high latitude, or by the polar climate, or by both. In this paper the various problems which arise are reviewed, possible solutions are discussed, and it is indicated where further research and experiment might be desirable.
Port Approach and Berthing in Fog
Authors: Wylie F. J.
Published: January 2010

In a recent paper on shipborne radar the authors tried to analyze the mental approach of a master or pilot to the problem of handling his ship in a confined space when berthing in fog. The sense of loss that is caused by the absence of direct vision was referred to and various means by which confidence and control might be restored in these circumstances were considered. In that paper only the inadequacies of present-day shipborne radar in meeting these requirements were discussed. The approach to the problem can, however, be broadened to include the whole question of port operation in fog, and the present paper attempts to describe the general requirements and to consider in particular the role of shore-based radar and the manner in which the information obtained from radar or other aids should be presented to the master.
High Altitude Observations at Sea
Authors: Black A. N.
Published: January 2010

It is difficult to get satisfactory noon observations when the zenith distance is very small, because the Sun is rapidly changing in azimuth, the sextant must be swung through a wide arc of the horizon, and the Sun only dwells at the highest altitude for a very short period. To avoid these difficulties it is suggested that, instead of trying to measure the altitude of the Sun, one should measure its distance from a point on the horizon in a known azimuth. To make this measurement the Sun is brought down to the required point on the horizon, tilting the sextant as necessary; we shall distinguish this type of observation from the normal one, made with the sextant vertical, by calling the angle so obtained thehorizon distance. At normal altitudes this method, however sound in theory, breaks down because one cannot measure the azimuth with sufficient accuracy. However, at very high altitudes the rate of change of horizon distance with change of azimuth of the point from which the distance is measured becomes so small that it is not necessary to know the azimuth with such precision. In fact, at a zenith distance of 1°, the largest we shall consider here, the greatest error caused by an error of 1° in the azimuth is l″, and for smaller zenith distances the maximum error is proportionately less.
The Effect of Observational Errors on the Avoidance of Collision at Sea
Authors: Hollingdale S. H.
Published: January 2010

At a meeting of the Technical Committee of the Institute held on 9 January 1963 it was suggested that recent theoretical treatments of the collision problem could usefully be extended to include a discussion of the near-miss situation and the effect of observational errors. The basic mathematical relations for near-miss encounters have been set out in this Journal on several occasions, notably by Sadler and Morrell, and in graphical form by Wylie. The recent paper by Parker deals with the effects of both systematic and random errors of radar observations of relative range and bearing.

My previous discussion of the collision problem was presented in terms of the idealized situation where two ships are on an actual collision course, in which case the sight line is in the same direction as the relative velocity vector (the relative track). To extend the results to a near-miss situation, one has only to redefine the angle α (see p. 24s of ref. 3) as the angle through which the relative velocity vector rotates when one or both ships manœuvre. I have pointed this out on a previous occasion: ‘The two craft need not be on a collision course; this definition of α applies equally well to a “miss” situation provided that no reference is made to the sight line.
A Manœuvre Criterion
Authors: Parker J. B.
Published: January 2010

The consideration of the effect of observational errors on the problem of manoeuvring ships at sea has, surprisingly enough, only recently become the object of attention by contributors to this Journal, though the basic background was provided many years ago by Sadler. The discussion at the Technical Committee of the Institute emphasized the importance of a statistical treatment of the problem and this led first to a brief note by myself in which systematic and random errors in range and bearing were discussed, and later to a full survey by Hollingdale in which it was shown that the total time to the instant of closest approach should be divided between observing time and manoeuvring time. An article by Proctor, though rather out of the main stream of the ideas pursued by the above mentioned contributors, breaks new ground in the sense that comparisons are made between different types of manœuvre on a probabilistic basis.
Prescribed Courses for the Navigation of the Great Lakes of North America
Authors: Burnham O. T. , Jansky C. M.
Published: January 2010

The Great Lakes of North America, four of which form the border-line between the United States and the Dominion of Canada, increase in size from east to west, Lake Ontario being the smallest but still 180 statute miles in length. Lake Erie is the shallowest, with an east to west extent of 236 statute miles. Lake Huron has a maximum length of 247 statute miles from south to north. Lake Michigan is the only one of the lakes entirely within the confines of the United States, extending 321 statute miles from north to south. The largest and deepest of the group is Lake Superior, where the principal sailing course from Sault Ste. Marie to Duluth is 383 statute miles.
An All-weather Navigational Aid for for the Dover Strait
Authors: Milwright A. L. P.
Published: January 2010

Whereas almost everyone seems to be agreed that a system of routing ships in the Strait of Dover offers the best solution to reducing the tragic wastage of life and ships that occurs each year in these congested waters, opinions differ on the system of routing that should be adopted.

A Working Group sponsored by the British, French and German Institutes of Navigation has considered the problem and their report has been published in the Journal. They recommended that the navigational aids in the area should be revised and that ships should be advised, by means of Sailing Directions and Notices to Mariners &c., to follow the tracks shown in Fig. 1.
The Automation of Merchant Ships
Authors: Wepster A.
Published: January 2010

The Dutch professor Polak has suggested that an increasing number of higher order specific human thinking functions such as memory, supervision, guidance, schooling, &c. will soon be eliminated and replaced by machines. This sounds alarming, but it should be viewed against the general background of the relationship between man and electronics. The entire structure of the working community in general, and on board ship in particular, is already and will be further influenced and changed by the ever increasing introduction of electronics in general and remote control and automation in whatever form in particular.
Target Tracking by PPI Display or by Automatic Computer
Authors: Gérardin L.
Published: January 2010

The observation of a radar display by a human operator leads to the establishment of aircraft tracks. These tracks are subsequently used by the controller. More and more often, it is proposed to replace both PPI display and human observer by an automatic computer, either special or general purpose, to perform tracking.

In the present paper the basic performances of these two modes of operation are examined, taking into account the psychological and physiological features of human vision and hence the mental association of the viewer. The computer is more precise, but more costly and, when saturated, the drop in performance is abrupt. The number of tracks handled by a human operator is small, but the brain is very versatile and works very well in confused situations, with a slower drop in efficiency than the computer.
Conflict Detection and Resolution in Air Traffic Control
Authors: Oakley B. W.
Published: January 2010

One of the principal functions of air traffic control is to ensure that aircraft do not conflict, that is, do not approach each other sufficiently close to give rise to the possibility of collision. (Another function of air traffic control is to ensure that aircraft do not conflict with terrestrial objects, but this is outside the scope of this paper except in so far as such objects can be treated as aircraft with zero velocity.) The ‘possibility of collision’ is, of course, a matter for definition. It is often treated as an approach within 5 miles in plan and 500 or 1000 ft. in height (Fig. 1). The definition must depend upon the form of the aircraft track information available to the air traffic service—essentially flight plans updated by pilot reports—or the radar observations with which this paper is primarily concerned.
The Accuracy of Upper-wind Forecasts
Authors: Durst C. S.
Published: January 2010

In a previous paper (Journal, 11, 180), the author gave assessments of the forecast wind errors likely to be met with at any point on the globe by an aircraft flying for one hour. The present paper follows this up by giving the probable errors of 24-hour wind forecasts over routes of any length, and thereby assesses the probable unpunctuality of aircraft owing to wind forecast errors.
Drift Determination in Jet Aircraft
Authors: de Jong H. M.
Published: January 2010

After the radar altimeter came into use at the end of the second world war, the combination with a pressure altimeter made it possible to measure horizontal pressure gradients, which enabled the navigator to estimate the geostrophic wind. The pressure gradient is directly related to the component of the wind at right angles to the track by means of the geostrophic relation and the navigator is thus provided with a method of evaluating one component of the drift. A position line of pressure combined with another position line (Loran, astro, &c.) enables the position of the aircraft to be determined.
The Last Voyage of Sir Clowdisley Shovel
Authors: May W. E.
Published: January 2010

Much has been written from time to time about the disaster which befell the fleet under Sir Clowdisley Shovel (or Shovell) among the rocks of the Scilly Islands on 22/23 October 1707. Although many writers have discussed the cause of the catastrophe I have come across no one who has examined the D.R. positions of the various vessels involved, and it is these which I propose to consider here.

It may be as well to recapitulate the story of the disaster. (At this time, it should be noted, the day at sea was measured from noon to noon and began twelve hours earlier than the civil day. Consequently, the afternoon at sea had a later date to that ashore. Noon positions logged were those at the end of the sea date.)
Space Navigation
Authors: Porter J. G.
Published: January 2010

The following discussion took place at an Ordinary Meeting of the Institute held at the Royal Geographical Society in London on 19 February 1960, with the President, Wing Commander E. W. Anderson, O.B.E., D.F.C, A.F.C, in the Chair. Dr. J. G. Porter is at the Royal Greenwich Observatory, Herstmonceux, Mr. D. J. Cashmore and Mr. T. McClymont are both with English Electric Aviation Limited.
Calculation of Charts on an Oblique Gnomonic Projection by Electronic Computer
Authors: Sarson P. B.
Published: January 2010

IN the Meteorological Office, great accuracy is not usually attainable in determining or forecasting the position of significant weather features. Special projections of charts are therefore not often required; the normal conic projection with two standard parallels or (near the equator) the mercator projection is quite adequate. However, in the radiolocation of thunderstorms a chart drawn on a gnomonic projection is required. The bearings of each lightning flash within one or two thousand miles are recorded from a small number of special stations (SFERICS stations). When these bearings are plotted on a gnomonic chart by straight lines drawn from the appropriate observing station the coordinates of the source of the lightning can be quickly determined and reported through normal meteorological channels. Speed is essential and therefore the charts on which the bearings are drawn are specially designed with the SFERICS stations grouped more or less evenly about the tangential point of the projection plane of the gnomonic chart.
Detection of Gross Instrumentation Errors
Authors: Parker J.B.
Published: January 2010

Mr. J. F. Green, in an article on gyro failure (this Journal, 13, 78). draws. attention to a principle that is of direct importance whenever navigators are dependent, for their information, on an equipment which, though normally serviceable, can develop a gross error. His principle is the triplication of instrumentation: the agreement between the two supposed serviceable equipments is a control on the possible malfunctioning of the third.