At the end of a conference held in London in June 1957 to discuss the avoidance of collision at sea and in the air, it was recommended that the three sponsoring bodies (the British and French Institutes of Navigation and the Ausschuss für Funkortung) should set up a representative Working Group to study the desirability of amending the Collision Regulations to take into account the use of radar.

The Group, which was formed in January 1958, was composed of the following members, not all of whom were able to attend every meeting: Commander P. C. H. Clissold (School of Navigation, University of Southampton), Captain W. H. Coombs (Honourable Company of Master Mariners, Barrister at Law), Captain R. Dublineau (Compagnie Générale Transatlantique), Captain P. Dupuy (Compagnie des Chargeurs Réunis), Captain H. Giessler (Ausschuss für Funkortung), Captain H. D. Harries (Regierungedirektor beim Bundesminister für Verkehr), Vice-Admiral K. Hoffman (Bundesverkehrsministerium), Professor P. Hugon (Professor Général d'Hydrographic, Rear Admiral, Ret.), Captain E. H. Ketels (Verband Deutscher Radar), Captain Le Bihan (Compagnie des Messageries Maritimes), Captain G. Lohmnitz (Norddeutscher Lloyd, Bremen), Captain P. Marchand (Ocean Weather Ship Service), Dr. F. W. Marienfeld (Bundesverkehrsministerium), Captain D. G. Tait (Honourable Company of Master Mariners), President Dr. R. Vogler (Bundesoberseeamt, Hamburg), Captain F. J. Wylie, R.N. (Director, Radio Advisory Service), Captain C. J. Wynne-Edwards, R.N. (Director, Compass Department, Admiralty Compass Observatory). The members of the Group served only in a personal capacity.

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 accurate, continuous determination of position, heading and course at all times, under all normal operational conditions, would be very desirable. This ideal has not been achieved for flights or voyages of long duration, but the many developments of recent years begin to give some promise that it may be possible. For high altitude aircraft the continuous optical observation of celestial bodies offers an evident solution, and doppler systems can give continuous speed over ground. For ships, however, the attainment of such an ideal navigation system is difficult. The various shore-based radio navigation systems have made important contributions, as have the development of inertial techniques. In addition, automatic optical sextants have been developed which can be used in clear weather.

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.

For many years there has been evidence (for instance from pilot balloon ascents and drift of cirrus clouds) of the existence of occasional very strong winds in the upper troposphere. However, it was not until about 1933, that Bjerknes, who had introduced the concept of the polar front during the first world war, produced a map of geostrophic wind deduced from upper-air temperature soundings made at a few scattered stations and showed a core of strong westerly winds at about 12 kilometres in middle latitudes in winter. No further progress was made until during the second world war when a comparatively large number of upper-air stations were set up and it was found that narrow belts of very strong winds were almost always present over some part of the Earth's surface in the 30,000/40,000 ft. altitude band. In 1944–5 American bombers encountered some rather frightening winds over the Japan area and since that time some extensive investigations of jet streams have taken place.

The term jet stream is popularly applied to any strong upper-wind current (of say 80–90 knots) and it is safe to assume that such winds are in fact associated with a jet stream, which may be considered as a narrow tube containing very strong winds embedded in the surrounding atmosphere.

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.

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.

C. S. Durst has tried to discover the frequency distribution of aircraft navigational errors from D. C. Willis's data. But how reliable are Willis's data for this purpose?

D.R. errors and track-keeping errors are differences between assumed and true positions. Evidence of assumed position is ayailable, but how can true position over the Atlantic ever be discovered accurately? Willis estimated true position by post flight analysis of navigational and meteorological data, but any such analysis must be based on some doubtful assumptions, for instance that compass error or wind was constant between fixes or that the true position was at the ‘middle’ of a ‘reliable’ fix. The analysis must also comprise many delicate judgments, for instance that the true position was at A, not B, because if it were at B an abnormal wind change must have occurred for which there is only slight evidence.

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.

Having had for some time to navigate small craft in all weather in the western approaches to the Clyde and on the west coast of Britain, the writer would like to submit for the consideration of other small-craft navigators some modification in chartwork which has proved useful, especially in rough weather when parallel rulers are an abomination and flying dividers can be lethal.

On a violently moving platform the navigator can only work with maximum efficiency when he is himself chocked off in a position in which he is sheltered, has the widest possible field of view, can take bearings and can brace himself securely to leave both hands free to carry out a limited amount of geometrical plotting with reasonable accuracy. The obvious position is of course the fore part of the wheelhouse, where there is very seldom sufficient room for a fullsized chart table with all the frills and trimmings.