bluuebunny/crossref_metadata_2025 huggingface dataset:
Air Navigation by Zenith-Photography
Authors: d'E. Atkinson R. , Hilder E. Brett
Published: January 2010

In this note, we propose to enquire into how far it may in principle be possible to employ zenith-photography for astro-navigation in the air, also to touch on the question of whether the mechanical difficulties can be adequately overcome. The question of principle seems in fact quite clear, but the practical side will undoubtedly demand much care and study by engineers and by practical navigators if the method is ever in fact to be adopted; we hope to show that the method has advantages sufficient to make the problem worthy of attention.
Errors in Observed Altitudes
Authors: Middendorp J.
Published: January 2010

I wish to thank Dr. Clemence for pointing out1 the flaw in the interpretation drawn in my paper that the error in observed altitude due to tilt of the sextant is a maximum when the altitudes are in the neighbourhood of 45°. The purpose of a correction table is either to supply the correction or to indicate the most favourable or unfavourable circumstances. I agree that my table does not fulfil this purpose; the argument β is unknown. Moreover the table gives corrections for all combinations of altitude and β this is incorrect, as some values of β are impossible for some altitudes, and a square form of table is therefore not permissible.
The Changing Navigation Routes of the Thames Estuary
Authors: Robinson A. H. W.
Published: January 2010

Reference to a chart of the Thames Estuary will show that the dominant feature of the submarine morphology is the series of elongated banks, of which the Barrow, Sunk and Long Sand are the most important. Between these banks, and with the same north-east to south-west trend, are the navigable channels of the Swin, Barrow and Black Deep (Fig. 1).

The alignment of the channels suggests that they originated as a result of tidal-stream scour of a fairly uniform sheet of fine silt and sand. In each tidal period, streams enter the estuary from the north and flow on the flood in a south-westerly direction parallel to the Essex coast. After about six hours they slacken, turn and flow out of the estuary in the reverse direction. This continuous flood and ebb stream action, with a maximum velocity varying from 2·3 to 2·9 knots depending on whether the tide is neap or spring, has apparently scoured out channels to depths which exceed 10 fathoms in places. If the channels largely arose in this way, the banks represent the modified remnants of the initial surface. These banks are constantly being extended seaward as more riverine silt is emptied into the estuary by the Thames, Medway and the rivers of Essex. The distal end of Long Sand alone has grown almost ½ mile in the past 100 years (see Figs. 1 and 4).
High Altitude Observations at Sea
Authors: Verstelle J. Th.
Published: January 2010

The method of taking high-altitude observations at sea described by A. N. Black in the April number of theJournalis not widely known and is undoubtedly of practical value, though it is not new. In his article Mr. Black regretted that he had had no opportunity of testing the method under practical conditions as his cruising range did not extend into the tropics. For this reason the results of some actual observations taken by the present writer some twenty-five years ago using this method may be of interest to Mr. Black and to readers of theJournal.

The author is in entire agreement with the first ten lines of Mr. Black's paper, though the termslant altitudeorinclined altitudemight express better what is being measured thanhorizon distance, which may be misleading. He does not however agree that the method is sound in theory for ‘normal’ altitudes, as will be explained. The method is in fact both practically and theoretically restricted to use with zenith distances of about i°, which is the limit actually considered in Mr. Black's paper.
Radio Aids to Navigation
Authors: Watson-Watt Robert
Published: January 2010

The objectives of navigation have, in the special case of air services, been summed up, in an ‘R.S.V.P.’ formula, as Regularity, Safety, Versatility and Punctuality. The formula holds for all navigation, since the object of every operator and every master is to carry his passenger or freight in safety on a preconceived time schedule, with virtually complete freedom of choice, by owner or master, of type of craft, of time of departure and of route. The enemies of this freedom of choice and of the preconceived schedule are almost wholly meteorological or astronomical; the only serious enemies are meteorological. The continuing concern of the ‘navigator’ proper is to avoid, detect and rectify departures from the preselected route and schedule. The whole task of ‘navigation’ is unfulfilled without an infallible look-out for dangerous obstacles, which may be at fixed and known absolute positions, or at random, variable and unknown positions relative to the craft. Good ‘eyes’ naturally or artificially aided and a good clock would be the only indispensable tools of whole navigation, were it not for those imperfections of the science and art of weather forecasting which leave the drift term in dead reckoning such a deplorably variable and unmanageable element in the dual problem of the navigator. That dual problem is ‘Where am I now?’ and ‘Where shall I be inxminutes from now?’ The unpredictability of the drift term and the imperfections of the navigator and his instruments prevent the answer to the second question emerging mechanically from the answers to the two much simpler and essentially similar questions: ‘Where am I now?’ and ‘Where was Iyminutes ago?’
III—The Meteorological Limitations on Pressure Pattern Flying
Authors: Sawyer J. S.
Published: January 2010

The preceding papers indicate that the theory of pressure pattern flying assumes that the wind satisfies the conditions imposed by the geostrophic wind equation and that the atmospheric pressure distribution is not changing. These conditions are not satisfied in the atmosphere, and the errors caused by their non-fulfilment are discussed in the following paragraphs.

Effect of departures of wind from geostrophic. The geostrophic wind equation is derived on the assumption that the wind blows uniformly without acceleration and without friction. These conditions are never satisfied in the atmosphere, nevertheless the practising meteorologist has found that the geostrophic wind represents a useful approximation to the true wind. There are certain exceptions of which the most important are in low latitudes and at levels below 2000 feet.
The Second International Meeting on Radio Aids to Marine Navigation New York and New London
Authors: Michell R. B.
Published: January 2010

At the first International Meeting on Radio-Aids to Marine Navigation held in London in May 1946 some 105 delegates of twenty-three maritime nations met to discuss and witness demonstrations of some of the remarkable advances made in radio-navigation during the war and to consider the progress made in relation to their peacetime uses for marine transport.

At the invitation of the U.S. government a second meeting was held a year later, in New York and New London, to show the progress made in America, to illustrate, with demonstrations, the U.S. policy and to pave the way to international standardisation. The U.K. delegation was led by Sir Robert Watson-Watt.
Navigation and Strategy in Ocean Racing
Authors: Illingworth J. H.
Published: January 2010

The technical processes of navigation are much the same in all craft, but there are certain requirements and problems which are peculiar to ocean racing. Compared with big ship navigation, the principal differences are:

(1) The ship's speed is irregular and is not always exactly known; it is also much lower so that the tidal streams and other sets play a much more important role.

(2) The course steered is often a constantly varying one, particularly when the vessel is on the wind, or before the wind.

(3) Leeway is a far larger factor.

(4) The violence of the motion and the lack of space greatly increase the difficulty of plotting and calculating.

(5) The methods of fixing the ship are generally less exact and less readily available.
The 3-Position Line Problem at Sea
Authors: Tyrrell A. J. R.
Published: January 2010

When simultaneous position lines are unobtainable a running fix or transferred position line is generally used. This method depends for its accuracy on the true assessing of course and speed. If, instead of transferring one of two position lines, three are obtainable, only the course need be assessed and used to obtain a position. It is assumed that the speed is constant, or nearly so—a reasonable assumption.
The Use of Consol in the Fishing Fleet
Authors: Harper D. H.
Published: January 2010

The present-day trawler carries more aids than any other vessel of comparable length and tonnage and, more often than not, more than the majority of big liners and cargo ships. She carries a powerful wireless transmitter giving an output in the neighbourhood of 100 watts in the modern sets; a main receiver with a standby, or emergency one, for listening in to ships of the same Company for information regarding the state of fishing in their areas; and one or two direction finders, one of which (known as a ‘fish snatcher’) is tuned to the trawler wave band to take snap bearings of rival ships who may be on a better living and foolish enough to say so. So far as Consol is concerned the direction finder is used to ascertain the sector in which the vessel is, should the accuracy of the dead reckoning position be in doubt.
Equivalent Tail-winds on the Shannon to Gander Route
Authors: Harley D. G.
Published: January 2010

An investigation has been made into the frequency distribution of errors in equivalent tail-winds on the great-circle air-route Shannon to Gander, as forecast at London Airport. In the course of the analysis the frequency-distribution of ‘actual’ equivalent head-winds as measured from the synoptic upper-air charts was also examined, and compared with seasonal means already published. The monthly extremes are tabulated and quarterly mean and standard errors are given, with frequency curves for the summer and winter half-years.
The Accuracy of Route Wind Forecasts for Aviation
Authors: Durst C. S.
Published: January 2010

In this paper values for the accuracy with which the meteorological forecaster can assess a route wind at 40,000 feet between London and Rome from his chart are suggested, and the accuracy with which he can forecast what the route wind will be is then calculated. These figures are then compared with an estimate of the accuracy of route winds derived from the navigation of aircraft over the route. Estimates of the errors that are likely to occur in wind forecasts for various air routes in operation or in contemplation are then made and a method of using wind forecasts is suggested.
II—Jet Streams and the Pilot
Authors: Frost Bernard C.
Published: January 2010

In the early days of civil aviation, aircraft flew too low to encounter jetstreams. Later they were no doubt encountered, when aircraft were flying at medium heights of from 10,000–20,000 ft.; however, the infrequency of astro fixing in those days would generally disguise a high-velocity wind by meaning it with low-velocity winds, producing resultant winds of medium velocity. Occasionally, however, very high winds would be experienced and the unexplained displacement of position would be attributed to a navigational error or some other cause of that nature.
The Hydrographic Collections of the British Museum
Authors: Skelton R. A.
Published: January 2010

The history of navigation and hydrography, as of other crafts or ‘mechanick arts’, has to be constructed from very imperfect materials. Instruments and charts, as the tools of practical men, were commonly discarded when they were worn out or superseded. The high mortality among original charts makes generalization in the comparative history of cartography hazardous. That no Portuguese charts before 1500 are now known does not allow us to conclude that none was made but only that none has survived. Many of the early charts that have been preserved are decorative examples drawn for royal or other patrons; those by which pilots conned their ships had a smaller expectation of life and are correspondingly rare.
The English and the Dutchman's Log
Authors: Taylor E. G. R. , Robinson A.H.W.
Published: January 2010

In his detailed and valuable account of the history of the Log (this Journal, 9, 70) Commander Waters is surely at fault as regards the part he ascribes to the Gresham Professor, Gunter. This eminent mathematician delighted in designing instruments with engraved scales, and at first issued the customary Description and Use in Latin, a sufficient indication that he wrote only for fellow scholars. Importuned probably by the instrument-makers, he later published English versions of the tracts (in 1623), and among the numerous ‘uses’ included a couple of chapters on those for navigational purposes.
I—Decca for Helicopter Operations
Authors: Adam J. G.
Published: January 2010

For a number of years helicopter operations will mainly take place at operating altitudes between 500 and 2000 ft. Due to the inaccuracies of existing pressure altimeters vertical separation less than 1000 ft. cannot be applied and therefore maximum use will have to be made of lateral and longitudinal separation possibilities if the development of helicopter operations in high density areas is not to be impeded. As far as possible helicopter operations will be kept apart from fixed-wing traffic but this may be difficult to achieve in terminal areas where departing and arriving fixed-wing aircraft are at low altitude and the available airspace is restricted.

It is, therefore, essential that the navigational aid on which air traffic control base safe separation should be one which enables the helicopter pilot to adhere strictly to his pre-determined track and also provides him with an accurate measurement of progress along track. Quite apart from the air traffic control aspect, since the helicopter flies low, frequently in poor horizontal visibility and low cloud-base conditions, accurate track keeping is essential from the standpoint of avoiding obstructions or high ground in the vicinity of the route. Accurate and solid coverage over a wide area at low altitude is therefore an important requirement of any helicopter aid system, particularly in a high traffic density area such as western Europe.
A Criminal Trial at Sea in 1582
Authors: Taylor E. G. R.
Published: January 2010

That a ship's captain may exercise supreme powers when at sea has been recognized since maritime laws were first formulated. But when Francis Drake summarily executed Thomas Doughty in Patagonia in 1578 there were serious misgivings at home, and the commanding officer of the next long distance expedition was hedged about with carefully thought out restrictions, and ordered, save ia the last resort, to bring any serious offender home as a prisoner. This voyage was organized and financed by the Earl of Leicester, Drake and a number of City merchants, its objective being to open up trade with the Far East by a voyage round the Cape. It had originally been intended to put Martin Frobisher in command, but for reasons unknown a gentleman and soldier of fortune, who had been with him on the second and third voyages to the Northwest Passage, Captain Edward Fenton, was substituted for Frobisher. This caused murmuring among the sailors who evidently thought poorly of him. And he did indeed turn out a weak, vacillating leader, though full of his own importance, so that the voyage was a failure, and two of his ships actually left him.
Operational Performance Standards for Civil Aircraft
Authors: Gillman R. E.
Published: January 2010

Throughout the history of aircraft design, a trend that has remained quite constant up to the present time is the steady increase of wing loading with successive types. This feature with its consequent raising of stalling speed, and therefore landing and take-off distances, has resulted in techniques rather more scientific than those used in the early days of civil flying. With take-off distances of anything up to 6000 feet, the pilot in deciding whether a particular airfield is adequate for a given aircraft is no longer the sole arbiter; the rule of thumb must give way to the slide rule.

The pilot is, of course, still responsible for the safety of a particular operation, and to help him in this respect, performance information for his particular type of aircraft is supplied in graphic form with the safety factor already built in. It is the purpose of this paper to explain why and how this is done.
Navigation in the Days of Sail
Authors: Shaw A. R. Perry
Published: January 2010

At the turn of the century I served in two four-masted barques under three captains hailing respectively from Nova Scotia, Liverpool and Glasgow. All three were rather elderly and their practice of navigation did not exhaust the theory even then included in the syllabus for second mate. However, it may be interesting to recall their methods.

The captains personally had to supply, in addition to sextants and nautical tables, chronometers, charts, ‘Pilots’, patent logs and nautical almanacs. I doubt if they bothered about tide tables. These were all kept in the captains' bedrooms. Each of these captains rented and insured two chronometers. In port, if convenient, these went ashore to a chronometer dealer and just before sailing were brought on board, each with a card showing its maker's name and number with error of instrument and its daily rate. If at sea it was possible to get a longitude by bearings of the land and also longitude by sights, they would be checked and error and rate corrected. Of course in sail it was impossible to maintain an even temperature in the chronometer compartment. It was generally assumed that, owing to effect of change of temperature on the lubricating oil, a chronometer ran slower in cold weather and faster in hot. I don't know when they were cleaned. Perhaps if a ship did return to where the chronometers' owner had his place of business they might be cleaned before being issued to some other ship.
The Work of the Institute
Authors: Irving Edmund
Published: January 2010

Presidential Addresses over the years have covered a variety of subjects, mainly scientific and generally devoted to navigation. Being neither a scientist nor, strictly speaking, a navigator, I have chosen the work of the Institute as the subject of my Address. Today, the Institute celebrates its twenty-first anniversary and we can suitably reflect on its growth and achievements. We are immensely proud of the fact that Your Royal Highness consented, as long ago as 1952, to become our Patron. We are always honoured and delighted that you have been able to attend so many of our Annual General Meetings and to take the Chair. You inspire us, Sir, to keep in full view the objects of the Institute, which were laid down in 1947 and which are:

‘To unite in one scientific society those interested in navigation’ and ‘To advance the science and practice of navigation and its associated sciences’.
Future Requirements for Autopilots at Sea
Authors: Wepster A.
Published: January 2010

Some forty years ago, in the early days of automatic steering, autopilots were looked upon as a mere addition to the gyro-compass equipment. It was a black box, which was said to be able to reduce fuel consumption. It was also a gadget that amused passengers. The original introduction of the autopilot was based on these two aspects and its application was consequently confined to a small number of large passenger vessels.

Yet the name autopilot clearly indicates the possibility of automating an important element of the ship's routine, the steering. However, at this stage shipping in general was not ready for this aspect. The cost of labour on board played a less important part then than it does today. It took another twenty years before it became clear that it was precisely the labour-saving capacity of the auto- or gyro-pilot which would play such an important role in the rationalization of the ship's manpower requirements.
Ground Movement Guidance and Control at Major Airports in Low Visibility
Authors: Harrison G.
Published: January 2010

The practical feasibility of blind take-off, landing and rolling to a stop has been adequately demonstrated, and both ground and airborne facilities are now being provided which will permit its progressive implementation operationally. Thus, one of the major questions remaining to be answered is the extent to which supporting airfield facilities are required to be improved in order to match the landing capability.

The present paper represents a contribution to discussion of the problems involved in ensuring that airport ground movements of both aircraft and vehicles can continue efficiently, and of the various measures which can be taken to minimize these problems. The conclusions drawn represent the opinions of the Blind Landing Experimental Unit, based upon the limited information which so far is available on this topic, and thus do not necessarily reflect firm U.K. policy since this must involve further study and investigation.
Hariot's Meridional Parts
Authors: George Frank
Published: January 2010

I Was interested to see Mr. Pepper's note in the July issue of the Journal. The intriguing question of Hariot's unexplained approach to a problem that appears to require a knowledge of the integral calculus and exponential functions had attracted my attention when Taylor and Sadler published their paper in 1953. In 1956 a note by me on this subject was published, with a comment by Mr. Sadler, which offers much the same explanation. I, too, was unaware that there was any evidence of Hariot's familiarity with the conformal property of the stereographic projection.
Distance by Vertical Angle—Height Unknown
Authors: Sayers P. H.
Published: January 2010

An interesting, easy and useful method of finding the observer's distance from a ship, buoy or isolated lighthouse, the height of which is unknown, is by measuring the angle between its waterline and the horizon. To this is added the angle of dip for the height of eye.

From the figure it can be seen that the angle so obtained is equal to the angle at the object between the observer's height of eye and his own waterline.
Radio Techniques for Automatic Systems in the Air
Authors: Mills J. R.
Published: January 2010

It is pointed out that the demand by navigators for more information in a given time or for the same information in a shorter time can only be met at the price of increased complexity (and, therefore, cost) and unreliability. To provide examples supporting this statement, a number of well-known systems are described briefly; for example, in the family of hyperbolic systems there is a clear indication that those providing immediate access to an unambiguous fix are more complex, in the wide sense, than those achieving similar accuracy but at the expense of ambiguities. This is even more true when various degrees of automatic operation and display are considered, and the paper includes a description of some of the techniques involved in the provision of these facilities. Finally, brief reference is made to the suitability for automatic computing of the geometry of the various systems and it is pointed out that those working in polar coordinates or Earth axes (such as VOR/DME and doppler/compass respectively) have advantages over the hyperbolic systems.
The Use of Radio Sextants in Automatic Navigation Systems
Authors: Cade C. M.
Published: January 2010

The basic principles of radio sextants are reviewed and their application is compared and contrasted with that of infra-red and visual wavelength sextants. For maximum versatility an automatic sextant should be able to operate both on radio wavelength and at one of the others. A complete automatic system requires not only a means of making automatic celestial observations but also a means of carrying the data forward—that is to say, as inertial reference. In the paper presented in Paris the development of inertial systems was briefly reviewed with particular reference to linear vibration gyrostats which lend themselves readily to light and compact systems where the highest accuracy is not required.

It is suggested that future developments in automatic navigation may well see novel forms of inertial reference coupled to radio sextants of millimetre wavelengths.
Height Information from Doppler Navigators
Authors: Beck G. E.
Published: January 2010

The possibility of obtaining altitude as additional information from an airborne doppler navigation equipment is reviewed, and some of the design problems involved are discussed briefly. These relate to the form of modulation used for transmission, the aerial beam shape and the direction of the aerial beams.

It is concluded that an accuracy of ±5 per cent. ±2 ft. over the range of 10–100 ft. might be possible. The work is in an investigational stage, and no specific design is described.
The Reduction of Weather Minima and the Improvement of Scheduled Regularity
Authors: Majendie A. M. A. , Gorham J. A.
Published: January 2010

The inter-relationships between the application of such airborne devices as automatic landing, head-up instrument displays, flare-out computers, and the like, their effect on operating weather minima, and the consequential benefits that may be derived in scheduled regularity, are very involved. The purpose of this note is to set out in simple terms the more important factors so as to provide a framework for further discussion. A cardinal theme of this discussion is the close association between the techniques needed to improve regularity, and those needed to improve safety.

The landing of a transport type aircraft is a task of a routine and repetitive type. It takes place within a fixed envelope of conditions that can be fairly strictly defined, and a high order of precision is needed compared with other phases of normal flight. The repetitive consistency that can be achieved by automatic means makes it natural to consider such a solution. Once such a system has been developed to a satisfactory level, the accuracy and consistency of the landing manœuvre will undoubtedly be much better than can be achieved by a human pilot.
On the Stopping Distances of Giant Vessels
Authors: Tani H.
Published: January 2010

This paper considers a practical solution to the stopping distance of ships, with particular reference to modern giant tankers. One solution to the problem has already been evolved by Captain H. Topley of the Honourable Company of Master Mariners. The present paper tackles the same subject from quite a different viewpoint.

The basic assumptions on which the mathematical treatment has been based is presented in Section 1, which also includes the calculation formulae of the speed and distance run at any time in a manœuvre, without proofs. Section 2 deals with clarifying the essential differences between Captain Topley's theory and the author's. The validity of the theories is examined in Section 3 by comparison with the results of actual ship tests. Section 4 presents calculation diagrams prepared by the author.

The only reliable data available by means of which captains can predict the stopping behaviour of their ships after ordering STOP ENGINES are the results of inertia tests conducted at the sea trials when the ships were built.

The inertia tests, however, are usually performed for only one case in which the approach speed is assigned to HALF AHEAD or the so-called manœuvring full ahead speed. Therefore most masters are glad of any knowledge of how to predict the movements of ships from any reduced speed.
IV—Doppler and Civil Aviation
Authors: Fraser D. O
Published: January 2010

Those familiar with the history of navigation aids may, with good reason, be reluctant to look upon any new aid as a panacea, but there appears to be no doubt that doppler will effect a revolutionary improvement in air navigation as we know it today. We have, for the first time, an aid self-contained in the aeroplane, independent of propagation conditions or weather, capable of giving position information anywhere over the globe with an accuracy certainly adequate to join the approach facilities at the destination aerodrome. Some of us not actively engaged in flying the world's routes tend to be influenced in our outlook by the navigation problems and facilities in high-density areas like western Europe, the United States or even the North Atlantic, and we are inclined to forget that this is only a very small part of the world route structure. The intensity of aviation activity in these high-density areas warrants the establishment of a network of radio beacons, ranges, VOR's and space pattern systems like Loran and Decca to bring order into the traffic flow, besides assisting the navigation of individual aeroplanes. When, however, we consider the immense distances flown by aircraft through Africa and India to the Far East and Australia, to South America and across the Pacific, to say nothing of Communist Asia, we begin to realize what a real dearth of navigation facilities there is over the globe.
The Earth but a Satellite of the Sun
Authors: Taylor E. G. R.
Published: January 2010

New ideas of a really fundamental character are always received with horror and alarm by the general public, and are vigorously repudiated. When Fred Hoyle, in a brilliant series of broadcasts, remarked that his physico-mathematical calculations indicated that newly created hydrogen was being continuously injected into the Universe, the B.B.C. had to take hasty countermeasures. A well-known authoress of detective stories and religious pl ys, followed by a respected professor of science, declared on the air that the earlier t lks had been merely speculative. A similar role was filled in 1543 by the theologian Andreas Osiander, who added a Preface to Copernicus's startling book De Revolutionibus Orbium Coelestium (the author having just died), to the effect that he had only intended as a mathematical hypothesis, not as a matter of fact, to picture a rotating globe revolving round the Sun. From the point of view of pure geometry it was, it is true, merely a matter of a change of coordinates. People settled back comfortably for another sixty or seventy years, until Galileo made certain awkward observations with his new telescope.
I — Sailing the New Mayflower
Authors: Villiers Alan
Published: January 2010

When I heard about the idea to sail a replica of the Pilgrim Fathers' Mayflower from England to America, I liked the notion. It was not my idea and I had nothing to do with the promotion. What I did was to volunteer to find a British crew and sail the ship, when she was ready—to get her across the Western Ocean, the way the original ship had gone over three and a half centuries ago. I have listened to a good many pessimists who have alleged that sailormen were dead and gone in Britain today, who declared mournfully that nobody could be found to sail ocean-going square-rigged ships in this country, and averred that, in any event, no one could possibly have the least idea how to handle a museum-piece come to life, and so on and so forth, ad nauseam.
III—The Voyage of Sputnik
Authors: Porter J. G.
Published: January 2010

The Russian Sputnik travels rather faster than the Mayflower or even a transatlantic racing yacht, and the launching of this artificial satellite is truly a wonderful achievement. I want to tell you why I think so, and what it means for the future.

The satellite, which was launched on 3 October, has already made 300 revolutions about the Earth. Its speed is about 17,000 miles/hour, which is about 280 miles a minute, and it makes one revolution about the Earth in 96 minutes—that is, 15 revolutions a day. Its track is inclined to the equator at an angle of about 65 degrees, so that at one time it goes up to the Arctic Circle, and at the other end of its path down to the Antarctic.
Controlled (h/d) Flight Path System for use during Climb and Descent
Authors: Ryan R. D.
Published: January 2010

An attachment giving a number of accurate straight or curved climb or descent flight paths has been developed for use with the Australian-designed airborne distance measuring equipment (DME). The electrical output from a special altimeter is converted into a time delay which increases with altitude. In the DME distance is measured, fundamentally, in terms of a similar time delay. The h/d flight path is defined by keeping these two delays equal as the aircraft climbs or descends. The ILS glide slope meter is used as the pilot's path indicator. Nominal slopes from 1° to 6° may be selected. In terms of height, deviations from the path of ± 250 ft. produce full-scale deflections on the meter, while the maximum error is ± 1000 ft.
Precise Radar Conning
Authors: Robb E. M.
Published: January 2010

The use of leading marks in pilotage is a procedure familiar to all seamen, and wherever leads are sufficiently easy to recognize on the screen the technique can be extended to use with radar, due note of the lowered degree of precision being taken. In this account of a passage through the exit to Singapore Strait, Captain Robb, a shipmaster of the Blue Funnel Line, and author of several works on radar use at sea, describes a less well known method in which off-set marks are used for conning the ship by radar. A similar technique was suggested in the Journal (9, 445) by Mackay.
International Cooperation in Hydrography
Authors: Ritchie G. S.
Published: January 2010

In the eighteenth century nautical charting was a wholly national activity carried out to facilitate the navigation of the nation's own men-of-war and merchantmen. Regarded as what we would today term classified material, the charts were not freely exchanged with other nations for they could aid potential enemies, either in the competitive field of overseas trade or in the strategy of fleet operations. Indeed in the Napoleonic wars marine disasters caused by natural, and often uncharted, hazards were the major cause of casualties on both sides.
Time Data and Navigation
Authors: Smith Humphry M.
Published: January 2010

In 1972 an atomic time standard based on the fundamental properties of the caesium atom is being substituted for Greenwich Universal Time, based on the rotation of the Earth on its axis, as the ultimate control for international time signals. Greenwich Time and longitude are inseparable, so that any necessary correction to the time signals he receives will be of vital importance to the navigator.

This paper was presented at a meeting of the Institute in London on 27 January 1970 with the Hydrographer of the Navy, Rear-Admiral G. S. Ritchie, C.B., D.S.C., in the Chair. Mr. Humphry Smith, head of the Time Department at the Royal Greenwich Observatory and Chairman of the Directing Board of the Bureau International de l'Heure, reviews the relationship of uniform time systems to the precise astronomical observations that determine the irregularities of the Earth's rotation. He outlines the current proposals for time signals, their correction to Universal Time and the implications for the navigator.
Low Light Television and its Application to Navigation
Authors: Corps R. J. , Hicks A. G.
Published: January 2010

This paper was presented at a joint meeting of the Institute and the R.A.F. Specialist Navigation & G.D. Aero-Systems Course Association in London on 21 April 1971, with Group Captain D. F. H. Grocott, C.B.E., A.F.C., in the Chair. At the meeting the paper was illustrated with many slides which greatly facilitated understanding of some passages. Only a proportion can be reproduced here.

Obviously there are many occasions when the navigator would like to retain a full visual capability at night; this is certainly so in the military context where it may be essential that aircraft operations shall be fully effective under night conditions. It is similarly a truism that the acuity of the human eye, that is the ability to resolve fine detail in the image, decreases as night falls and the illumination level is reduced. Because of this there have been many research programmes over the years to develop sensors to extend the capability of the human eye, and one of the most important developments has been the use of low light television (LLTV) systems as an aid to night vision.
A Manœuvring Diagram for Avoiding Collisions at Sea
Authors: Cockcroft A. N.
Published: January 2010

In 1970 the Institute formed a Working Party to formulate views on the revision of the collision regulations. Its Interim Report is published in the Journal for October 1970 and two further contributions, by Calvert and García-Frías, were published in a subsequent number (24, 413–20). The Interim Report referred to the value that a manœuvring diagram along the lines originally proposed by Calvert and Hollingdale would have in helping the mariner to assess the effects of collision situations on alterations of course and speed. It has not been possible to secure unanimity about the form of this diagram, but the one illustrated below is based on the contributions of several members and has met with the approval of the majority of the Working Party.
Historical Hyperbolae
Authors: Powell Claud
Published: January 2010

At a first glance, one of the two accompanying diagrams might be taken to represent a three-station Decca or Loran chain, while the other offers familiar instruction on how to interpolate between the lattice lines and plot the fix. In fact, these are illustrations in a German Army handbook entitled An Introduction to Sound Ranging and the Work of the Sound Ranging Section, published in July 1918.
Distance by Vertical Angle
Authors: Cotter Charles H.
Published: January 2010

The note by V. L. Bosazza (on page 112) raises a number of interesting points. First it must be noted that there is no indication in Ryder's book that the horizon method, viz. ‘To observe from the cross-trees or other convenient place the angle subtended between the horizon and the enemy's waterline’, was used before it was introduced by Ryder in 1845. Ryder remarked that in not a single man-of-war which he visited before the time of the publication of his book did he find any method in use that would denote satisfactorily the range of a ship at sea; and it was to meet this deficiency that he suggested his horizon method.
The Knife as a Compass
Authors: Heinesen Fischer
Published: January 2010

When our Norwegian ancestors wished to navigate in the open sea they could find their bearings by the Sun or stars if the sky was not overcast. In foggy weather they used the sólaisteinn or sunstone, ‘a stone with which one could see where the sun was in the heavens’. A knife blade will do equally well as may be seen from Fig. 1. If you place the point of the knife on your thumb nail, as shown in the figure, on a sunny day you can easily see the shadow it casts; turning the blade a little one way or the other the shadow widens, but when the knife edge points towards the sun the shadow is reduced to a narrow line.
On the Frequency Distribution of Large Errors
Authors: Crossley A. F.
Published: January 2010

In various papers published recently in the Journal and elsewhere, examples have been given in which the theoretical normal or gaussian distribution of errors does not correspond closely with the distributions found in practice; in particular the frequency of large errors is commonly underestimated by the normal law of errors. This discrepancy is discussed by Anderson who suggests that an exponential distribution may give a more realistic estimate of the frequency of large errors. A closely associated problem is that of determining the frequency distribution of the largest values occurring in a number of samples taken from some parent population. This problem has been solved theoretically for an important class of distributions and it is the object of this article to draw attention to this work and to show how it can be simply applied to practical problems, albeit in a rough and ready manner, without going far into the statistical details with which the subject abounds.
I—The Requirement
Authors: Davies W. P.
Published: January 2010

The following papers were presented at a meeting of the Institute held in London on 12 March 1965. Mr. W. P. Davies (Polhemus Associates) first outlines the height measurement requirements for a supersonic transport aircraft. The other speakers review the available techniques: Mr. R. Whalley (Ferranti) dealing with inertial techniques, Mr. B. Cape (S. Smith & Sons) with pressure measurement techniques and Mr. W. L. Garfield (Standard Telephones and Cables) with radio altimetry. Mr. G. E. Beck (The Marconi Company) describes a recently developed radio altimeter.

1. Introduction. In outlining requirements for height measurement in supersonic transport aircraft it should first be said that not all the requirements are special to supersonics. Some of the requirements are the same as already exist, or will exist in the 1970's, for subsonic aircraft. The main problem in supersonic aircraft will be to maintain the same accuracy over increased measurement ranges of height and height rate and in an environment of higher speeds and temperatures. Where-ever possible then, the requirements are of the same standard expected for subsonic aircraft of the 1970's. More stringent requirements are stated only where they are considered necessary; there are enough real problems in the advance to civil supersonic operations without creating artificial ones.
Navigation and Economics in the Air
Authors: Williams J. E. D.
Published: January 2010

‘Navigation demonstrateth how, by the shortest good way, by the aptest direction, and in the shortest time a sufficient ship between any two places may be conducted.’ To our Elizabethan forebears it was evident that the best way to conduct a ship was by the shortest passage of time which engendered least risk of catastrophe and avoided excessive wear and tear on ship, equipment and possibly passengers and crew. In the age of value-engineering and cost-effectiveness we are required to quantify these conflicting criteria. This is a matter of economics, which is concerned with applying the finite resources of mankind to the satisfaction of its infinite wants.
Navigation in Animals
Authors: Matthews G. V. T.
Published: January 2010

The last twenty-one years have seen some very striking advances in our knowledge of how animals can determine their location. In many cases we have learned that they have available a wider range of stimuli than ourselves for recognizing landmarks and for pilotage within their home area. Thus the associated senses of smell and taste are extraordinarily well developed in some species. The ability of the males of certain moths to detect the scent emitted by females at very considerable distances had long been known. More recently the extreme sensitivity, and selectivity, of fish to waterborne odours has led to an understanding of how they locate their home waters.
Distance-off by Angle of Depression
Authors: Thompson P. A.
Published: January 2010

Mr. P. H. Sayers (this Journal, 21, 83) proposes a method of finding the observer's distance from a ship, buoy or lighthouse, the height of which is unknown, by measuring the angle between its waterline and the horizon, the angle thus found being reduced for the dip of the sea horizon for the height of eye. Table 1, an enlargement of the table which the author has used for some 15 years, gives the same information. It requires no correction for dip.
Shore Radar Control in the Port Entrance Area
Authors: van Hooff J. F. Drijfhout
Published: January 2010

The paper discusses the measure of control to be exercised by the Port Authority in a Port Entrance Area where shore radar enables tracks to be made of all ships present. The problem becomes acute where great numbers of ships are trying to enter and leave in restricted visibility, creating danger and confusion.

In a previous paper presented at the conference, Commandant R. Betton, Captain of the Port of Le Havre, suggested that it was perfectly possible for shore-based guidance radars to be used to reduce collision risks at the entrances to harbours, provided this supplementary function is precisely denned in terms of how much authority harbour administrations can exercise over ships outside the harbour. Betton stipulated that any control should only be exercised by experienced seamen and that they should not have the right to interfere in manœuvres for which masters should have sole responsibility.
Refraction at Low Altitudes
Authors: Sadler D. H. , Scott W. A.
Published: January 2010

The analysis of low-altitude observations of celestial bodies specially made for the purpose, indicates that no significant amendment is required to the refraction corrections published in the (Abridged) Nautical Almanac.

In recent years there has been an increasing interest in low-altitude astronomical sights, particularly in regard to the accuracy of observation and of the corrections to be applied for atmospheric refraction. As a result of the analysis of many thousand observations made under different conditions, Professor C. H. Smiley had deduced tabular refraction corrections which differed significantly from those in current use and also from those deduced from modern theories. Suspecting some systematic error in Smiley's results, possibly associated with the phenomenon of irradiation, Dr. G. M. Clemence of the U.S. Naval Observatory undertook an independent investigation using observations made at his request by ships of the U.S. Merchant Navy. Although the number of observations was rather small, leading to a fairly large uncertainty in the deduced refractions, there was little possibility of any source of systematic error; the observed values agreed with the theoretical values well within their observational uncertainty, and differed significantly from those of Smiley. A systematic difference between the observed altitudes of the upper and lower limbs of the Sun was ascribed to irradiation (the spreading of a bright image on the retina of the eye, making the diameter of a bright object appear larger than it is) and, taken in conjunction with a similar phenomenon depressing the visible horizon, was allowed for by subtracting 1.2 from the observed altitudes of the Sun's upper limb and leaving those of the lower limb unchanged. This correction was later incorporated in the altitude correction tables of the (Abridged) Nautical Almanac.
A Microwave Position-fixing System
Authors: Smyth H. R.
Published: January 2010

Shortly after merchant marine radar came into use as a navigational aid, it was felt that some consideration should be given to the development of electronic aids for vessels too small to use radar, such as tugs and fishing vessels. It was obvious that the use of the microwave frequencies of radar would best suit the development of a small directionfinding receiver. The final system developed by the National Research Council used a compact 3-cm. pulse transmitter on a shore site, such as a lighthouse, or harbour breakwater. The antenna was designed to radiate energy across the water from all angles of approach.

The receiving equipment was built into a case on the back of a small radar antenna consisting of a six-inch slotted waveguide at the focal plane of a parabolic cylinder. The receiver used a radar crystal detector and transistorized audio amplifier for reception on phones or a speaker. The receiver could be hand held or mounted on a pelorus head, and rotated around the horizon to take a bearing on the shore transmitter. The signal from the shore is audible over an arc of only about six degrees, and can be maximized with an accuracy of ± 1 degree.