The monograph which follows has been prepared for the Institute by Wing Commander E. W. Anderson and Mr. J. B. Parker, working closely with Mr. D. H. Sadler. It was designed primarily for publication in book form; however, the Council has decided to publish it in the Journal as well, so as to give it the best possible circulation among members. This arrangement has meant varying slightly the normal style of presentation in the Journal and apart from the title page and page numbers there is no difference between the published book and the pages which follow.

The development of automatic dead reckoning navigation instruments owes its main impetus to the needs of the airman during the second world war. It was foreseen that manual plotting would not be adequate, for example, in bomber operations where frequent changes of course are desirable and speed and height are not always accurately maintained, and it was realized that automatic computing of position would provide improved reliability and accuracy. The instruments developed have been described elsewhere, and this paper outlines their early history rather than details of their design. It also indicates some future possibilities.

Existing instruments. The main instrumental aids to dead reckoning navigation which came into use during the 1939–45 war were the distant-reading gyro-magnetic compass, the air mileage unit and the air position indicator. From them evolved the ground position indicator and the wind finding attachment, both used for special purposes towards the end of the war.

Early in the 1930's Captain L. C. Bygrave constructed an experimental instrument which undoubtedly influenced later developments. This instrument was to be fed by a gyro-magnetic compass with heading and from an air log with air distance; on it could be set wind speed and direction and aircraft speed and course. The instrument showed departure in miles north-south and east-west.

IT has long been realized that the small fishing craft are inadequately supplied with modern navigational aids, and the reason why the most modern aid, radar, is not used is because its cost, weight and electrical power requirements are too great. In Great Britain a large number of small-boat fishermen, for instance in the herring drifter fleets, use Consol for offshore navigation, but this is not sufficiently accurate for navigating into harbour in bad visibility.

In 1951 the National Research Council of Canada undertook the development of a microwave course beacon as an aid to entering harbour. In 1953 the Ministry of Transport & Civil Aviation Group at the Admiralty Signal & Radar Establishment undertook the development of a similar beacon with a view to simplifying the shipborne equipment.

The beacon system is an adaptation of the old Lorenz type aircraft landing aid and consists of a microwave radio transmitter mounted at a harbour entrance and radiating in turn from each of two aerials which have beams overlapping in the horizontal plane. The transmitter is so sited that the line of intersection of the two beams lies along the safe course line for entering harbour. (Fig. 1 shows the orientation of the beams at the Scottish fishing port of Arbroath.)

ON 24 October the second of the Institute's annual series of lectures for nautical school cadets was held, once more under the general title ‘Off the beaten track’, at the Royal Geographical Society's house. Over 550 cadets attended, from H.M.S. Conway, H.M.S. Worcester, the Nautical College Pangbourne, the School of Navigation, Southampton, King Edward VII Nautical School, the London Nautical School, the Reardon Smith Nautical College and the T.S. Arethusa. Members of the London Area Sea Cadet Corps and of the Westminster Sea Scouts also attended.

Before considering what animals can do, without conscious thought, in the way of navigation, it would be useful briefly to review their ability to pilot themselves, to find their way around an area in which they have already had experience. Here landmarks play an obviously vital role, and in many cases they are visual landmarks which we can appreciate ourselves. But often the characteristics of the environment to which the animal reacts are non-visual, detected by senses similar to ours but of much higher acuity. The sense of smell is of dominating importance among the mammals, which will go so far as to provide their own ‘scent flags’ along the boundaries of their private preserves. Sounds are often used to guide animals, particularly to another member of their species or to their prey. The bats have gone further and rely on a form of echo-location for guidance of their fast erratic flight through the darkness. They emit high-pitched, if not supersonic squeaks and detect and analyse the reflections back from obstacles even so slight as a piano-wire stretched across their path. Animal ‘sonar’ of this kind has also been demonstrated in a bird and probably is also to be found in fish and porpoises. Certain snakes are believed to detect their warm-blooded prey by special heat-receptors in the head. Many other examples could be cited and our knowledge of the means by which animals can determine their course in familiar territory is probably not yet exhaustive. We are only just beginning to appreciate and understand what they can do when they are in completely unfamiliar areas or when, known landmarks are present but cannot be used.

I went to sail with the Arabs after selling the ship Joseph Conrad, which had proved too expensive for a private citizen to continue to run indefinitely as his own school-ship. I had always wanted to see something of Arab navigation because they were the pioneers. Semitic navigators and mathematicians were among the experts gathered by Prince Henry the Navigator at the school at Sagres, in Portugal, and the dhow voyages of the western Indian Ocean were very old. But I found that today the Arab dhow-captains do not ‘navigate’, as such: they apply personal knowledge to coasting passages, even though the passages cover some thousands of miles. For example, in a big double-ended dhow of the type known as a boom, from Kuwait, I sailed some 8000 miles in about eight months—down the east coast of Africa with the favouring north-east monsoon, as far almost as the monsoon blew, and then back again up the coast in the transitional period between the monsoons.

Two problems concerned with the use of radar to reduce the risk of collision are frequently called to mind by reports of casualties and correspondence relating to them. One is that of avoiding the ‘region of collision’ and the other is how best to proceed within such a region when it is unavoidable. The writer's attention was recently drawn to that phrase as it was used in 1932 in the judgment of the Court of Appeal on the collision between Haliotis and Chisone. The phrase caught the eye because of the need (in the writer's view) of a striking term to appeal to the imagination of some incautious mariners and impress them with the undesirability in fog of leaving too much to chance; it seemed to have more significance than the term ‘close-quarter situation’.

In the case in question the Chisone was found partly to blame because she did not stop her engines until five minutes after hearing the fog signal of the Haliotis. Although she was stopped, or nearly so, some minutes before the collision, she had come directly into the path of the Haliotis and so was considered to have committed the breach of Art. 16 (Rule 16 (b)) ‘in the region of the collision.’

Announcement. As from the editions for the year 1958 the Abridged Nautical Almanac and the American Nautical Almanac will become identical in content, and will be reproduced from identical material, apart from the title pages and covers; they will for the time being retain their present titles, and will continue to be printed and published separately in the United Kingdom and the United States. The unified Almanac will be produced jointly by H.M. Nautical Almanac Office of the Royal Greenwich Observatory, Herstmonceux, and the Nautical Almanac Office of the U.S. Naval Observatory in Washington, to meet the general requirements for surface navigation in the two countries.

Unification became a possibility with the decision to prepare copy for the Abridged Nautical Almanac on the card-controlled typewriter in H.M. Nautical Almanac Office; this machine is identical with that at the U.S. Naval Observatory, which has been used to prepare copy for the American Nautical Almanac since 1950. A large number of arrangements were tried for the daily pages, some with one day to the page or two days to the opening, and others with three days to the opening. The consensus of opinion in the United Kingdom favoured the latter form, which is already in use in the American Nautical Almanac. This opened the way to a detailed investigation into an arrangement that would prove acceptable to users and producers in both countries. The unified Almanac is the result of this collaboration.

Impatience is frequently expressed at the slow rate of progress in improving the efficiency of air traffic control. It is being expressed most forcibly at this time in the United States, because the military services require the separation problem to be solved for the large numbers of military jet flights, and because civil jet aeroplanes have been ordered by the airlines and will soon appear on the Federal Airways. Although a great deal of basic study has been made of the problem of air traffic control, it is becoming clear that there is no panacea for its solution. Air traffic control is concerned with the safe expeditious flow of air traffic. This involves a number of separate but interrelated problems both in the aircraft and on the ground. Thus we see a programme of development on a very wide front involving navigation aids, communications, radar performance and presentation, data display and so on. Progress in any one field may affect the requirements in another, and so it is most necessary for all concerned to have a clear view of the situation as a whole in order that they may see the wood as well as the trees. Lively discussion of the subject can therefore be most fruitful, both among those directly concerned—the pilots and the controllers—and among the specialists in the various branches of development.

A recently discovered ‘Navigational Notebook’ contains an interesting account of day-to-day navigation during the early part of the eighteenth century. The document was brought to light by Mr. J. R. Timms, a student at the School of Navigation of Southampton University, whose father discovered it in a bank at Ventnor, Isle of Wight, its depositor long deceased and no longer known or traceable. The date of the manuscript is uncertain but references to John Robertson's Elements of Navigation and Archibald Patoun's Epitome seem to place it after 1730. However the account of actual navigation is given in the journal of a voyage, in 1704, from the Lizard to Madeira, which is reproduced in the Notebook. It seems likely that the author, John Wilson, eventually came ashore as an instructor in navigation (and probably mathematics) and copied out the journal from one of his earlier voyages for the benefit of his pupils. Whether this is a later work by the John Wilson referred to in E. G. R. Taylor's The Mathematical Practitioners of Tudor and Stuart England is not clear.

When, over twenty years ago, Admiral J. A. G. Troup wrote his admirable book On the Bridge, he said that he had searched his soul to find a reason for burdening even one of his brethren with his observations on handling ships. That his diffidence was quite unfounded is, of course, proved by the fact that his book, at any rate in naval circles, has become a near classic. The fact is that there is remarkably little real opportunity for junior officers at sea to gain experience in the actual manœuvring of ships in restricted waters, and aspiring shipmasters will seize with avidity any crumbs of knowledge which may fall from the table of the experienced. And, while it is clearly true that much practical experience is essential, that experience will be dearly bought and largely wasted if the underlying principles are not clearly understood, and unless the practitioner learns what he must look for, and what will affect the issue. How often has one made, or heard others make, some such remark as ‘and then the wind caught her bows and I couldn't do a damn' thing about it’. But on reflection one realized that the observation should have been qualified by the admission that one had got into what, in sailing parlance, is known as ‘the hopeless position’, and should never have been there at all if a proper appreciation of the problem had been made.

I am of the opinion that the figures in Mr. Durst's paper have been obtained primarily from the main civil operators and that the results are not necessarily valid for military aircraft. Before accepting Mr. Durst's paper as a reference work for all aircraft it would be necessary to know the answers to the following questions:

(a) Were the navigating officers of each aircraft experienced practising navigators or were they perhaps ‘third officers’ occupying the seat to obtain navigational experience?

(b) Were the aircraft equipped with and did the navigators use Loran equipment? If so, were the operators adept at using sky-wave signals?

(c) Were the aircraft fitted with air mileage units and air position indicators?

(d) Were the aircraft fitted with remote indicating compasses with performance characteristics equal to those of the G3 and G4B (CL2)?

(e) Were the radio compasses swung at regular intervals?

When I was a member of the Transport Command Examining Unit (1949–51) one of my tasks was to assess logs and charts of experienced navigators flying the main trunk route from the United Kingdom to Australia. I can say quite confidently that as far as the 200 kt. aircraft are concerned a D.R. error of 8 n.m. per hour proved to be an excellent working approximation. Seldom did circles or ellipses of errors around fixes and D.R. positions not intersect or give a ‘sensible’ wind.

‘The Earth is an ellipsoid’, says the Admiralty Navigation Manual firmly, although in a later volume the expression is softened to ‘approximately ellipsoidal’, For in fact, as was implied by Captain Topley, the exact shape of the Earth is not yet known. Nevertheless, for nautical purposes it appears sound teaching practice to consider it a perfect sphere and then explain the departures of the nautical mile or minute of arc from its mean value. Nor need one quarrel with the Manual's statement that ‘to regard certain small triangles as plane is not to disregard the initial decision to regard the Earth as a sphere’. But the writer next indulges in an historical aside which cannot be allowed to pass. ‘This assumption (he says) gives rise to the expression plane sailing, which is popularly referred to as if plane were spelt plain and the sailing were free from difficulty’. But this is to put the cart before the horse. ‘Plain sailing’ was the original term, and it was only sophisticated into ‘plane sailing’ during the eighteenth century by teachers of navigation among whom John Robertson was the chief. Robertson was master at the Mathematical School of Christ's Hospital towards the middle of the century, and afterwards taught at the Portsmouth Naval College, finally becoming Librarian to the Royal Society. His Elements of Navigation was considered authoritative and ran into many editions, a later master at the Hospital, James Wilson, prefixing to it a Dissertation on the history of navigation which was also accepted as definitive. It is in this volume that we read: ‘Plane sailing is the art of navigating a ship upon principles deduced from the notion of the Earth's being an extended Plane. On this supposition the meridians are esteemed as parallel right lines…’, and the author goes on to what he terms the Plane Chart, with its equally-spaced meridians. There is little doubt that his passage is the source of the theory taught to modern sailors that ‘Plain Chart’ is a corruption of ‘Plane Chart’, while the latter was drawn by people who believed the Earth was flat. Actually we have only to go back a generation from Robertson to find an almost identical description of the chart—actually an equal-spaced conventional cylindrical projection of the sphere—but with the addition of the words ‘The rectangle formed by these meridians and parallels they (i.e. mariners) call the Plain Chart’. This was said in 1714 by John Wilson, a teacher in Edinburgh.

I think Professor Taylor and I are at cross-purposes in our discussion of the influence of scientists upon the art of navigation before the nineteenth century. Dr. Freiesleben expressed the view that until 1800, ‘when our technical age began’, there was a big gap between what interested scientists and what the seaman could understand and apply, that men of science were too remote from practical requirements. The implication was that scientists were not concerned with seamen's problems nor seamen with obtaining scientific help. I pointed out that whatever the situation in the eighteenth century might have been, in the sixteenth and early seventeenth centuries improvements of a radical nature were made by scientists, working with and for seamen, in the means of practising the art of navigation, in particular by English scientists working in the latter part of the period under the aegis of Gresham College and the East India Company. This is historical fact, little known perhaps, but none the less fact. I certainly never intended it to be understood that the seaman-scientist relationship peculiar to this period and resulting in such important developments typified, to use Professor Taylor's expression, ‘the degree of cooperation between sailor and scientist prior to the nineteenth century’. I intended it to be understood as being descriptive of the situation or relationship peculiar to the period in which it occurred, roughly 1550–1640 and more particularly 1598–1637.

In taking observations of the wind at sea, and in the study of the theory of air-navigation, it is often found difficult to give students a thorough conception of the relative (or apparent) wind. These notes are put forward to help instructors and others interested.

It is recorded that one of England's early Astronomers Royal went sailing on the Thames about 200 years ago, and what he learned that day made an advance in the science of astronomy. The Astronomer Royal was with some professional sailors, who must now be spiritual members of the Institute of Navigation. The learned gentleman was the Reverend Dr. James Bradley, who gave up his vicarage to become a professor of astronomy. The day in question had a wind of force four or five, but it was a steady wind, and the boat was tacking frequently.

At the masthead she wore a pennant, referred to by the doctor as a ‘vane’, and he noticed that it tailed away steadily enough down wind. But every time they went on to the other tack the direction of the pennant altered. The doctor was surprised that the wind should happen to alter every time they put about, but on mentioning this to the sailors he was told that the pennant only showed the direction of the relative wind, depending upon the direction and force of the true wind and the direction and speed of the boat, and their resultant changed every time they went about.