I remember that on V-J Day in 1945 a heroic band of Common-wealth delegates, greatly reinforced by the cooperative presence of colleagues from the United States, decided that they would not rise in celebration of victory but would continue their work, which included an estimate of the probable air-traffic density at the world's great airports in or about this year 1950. We made the best estimate we could of the numbers in which aircraft would in this present year be likely to be moving in and out of Heathrow (as it was then called), of Amsterdam, Brussels and Paris. Looking back through the mist of five years I detect a band of enthusiastic and starry-eyed optimists.

In this year of 1950 the British aircraft industry has an absolute and undisputed lead in the design and manufacture of civil turbo-jet and turbo-propeller aircraft. This time again I look forward, but I warn myself that we are another group of starry-eyed optimists if we think that another five years hence Britain will hold that undisputed lead, or will be comfortably established in a position of monopoly in the sale of jet-propelled civil aircraft.

This paper discusses the possibilities of using diagrammatic solutions for accurate astronomical navigation and gives a detailed description of two methods of doing so that have been put into effect in Germany. These methods, the ARG1 and the Astronomischer Rechenatlas, have previously been described in German publications and referred to in numerous reports and memoranda written in this country and the United States. So far as is known no authoritative description of these two aids to navigation has yet been published in English, and it is appropriate that this, the first, should have been written by Dr. Freiesleben, who played a prominent part in their development.—Ed.

The development of radio aids to navigation has not made astronomical navigation redundant, but it has given more force to earlier demands for the simplification of methods of reduction. No longer is it acceptable to have a large variety of alternative methods, and it is probable that attempts will be made to select a single method that is both simple and universally applicable.

This paper describes two methods by which lines of position may be obtained by observation of stars (in pairs) without the use of instrumental scale readings either for altitude or for azimuth. These lines of position represent arcs of great circles of the Earth. An instantaneous observation is proposed.

Great circles determined by star positions form, on the celestial sphere, a lattice which is not deformed by precession. Whether or not he be at rest relative to the rotating Earth, the observer's zenith traverses this lattice, which thus may serve in celestial navigation precisely as does a well-marked terrain in contact flying over land, or as do ranges and markers in coastal and harbour navigation. Observation of the zenith-transit of an element of this lattice is akin to the process of noting the moment when an aircraft crosses a coastal line or other visible terrestrial mark or to the recognition of when a vessel near shore is on a certain range. Observation of this type is as rapid as the navigator may be able to make it since it is the observation of the occurrence of an instantaneous situation.

Nature has provided few bright stars and these are unevenly distributed in the sky. Even for air navigation it is necessary to use stars fainter than the first magnitude. There is then a choice which rapidly widens as the limiting magnitude is decreased. Brightness is not the sole criterion; distributipn is also of importance. In choosing a number of stars for use in astronomical navigation, no two people can be expected to give precisely the same weight to small variations of brightness and distribution; there thus arise different selections for similar purposes. The navigator, however, expects that the star he knows and observes will be catered for in such lists; he cannot be expected to remember that a particular star (no fainter and perhaps even brighter than neighbouring stars) is in one list but not in others. Any rule which seeks to include all stars brighter than a given limiting magnitude results in too long a list and an uneven distribution. There is thus a strong case for the selection of a list of stars, to which permanent names and numbers can be attached, which can be used for all purposes of astronomical navigation.

It is now generally recognized that, under instrument conditions, traffic congestion at busy airports is already bad and any further increase in traffic density would be unmanageable without improvements in methods of air traffic control. A study of the problems of air traffic control by full-scale tests is prohibitively expensive and a practical alternative is required. This paper describes a series of investigations into air traffic control problems by simulation methods.

Laboratory equipment suitable for such experiments is described briefly and has been shown to give a reliable quantitative assessment of the effect of changes in a control system. A number of possible control systems were studied in detail.

Because of the greater speed of modern aircraft and the increasing complexity of air-traffic systems, air navigation is changing and breaking away more surely from its marine counterpart. This divergence means that navigational equipment designed for marine navigation is becoming less and less suitable for use in the air, and the special needs of air navigation are slowly gaining recognition. This paper concerns air navigation charts; its aim is to show the shortcomings of the charts at present in use, and to suggest a specification for a new style of chart that will meet modern requirements.

At the beginning it is well to define exactly what is meant by the word ‘Chart’. In I.C.A.O. terminology it is widely defined and includes amongst other things maps; but maps are a special case and their use is limited to visual flight. In this paper, therefore, the word is used in its older sense of a sheet upon which the actual navigation is performed.

Language holds many pitfalls for the unwary. A housewife picks up her iron, and so does the golfer: a butcher uses the steel and so does the soldier: a government nationalizes iron and steel. No wonder the foreigner makes ludicrous mistakes. And we in our turn, coming across an Italian book entitled Il Compasso da Navigare might be pardoned for supposing its subject-matter to be the navigating compass. This is not so. It is a learned and comprehensive treatise under the title belonging to the oldest surviving Sailing Directions for the Mediterranean Sea, and as the author, Bacchisio R. Motzo, clearly proves, such Directions were called a Compasso, and by a natural transference the same name was given to the sailing chart which was drawn to accompany the Directions. What we call a mariner's compass, or simply a compass, the Italians term Compasso-bussola or more usually just bussola. When English sailors began to use written Directions or ‘Pilots’ they called them Rutters (from the French Routier), while an alternative Italian name for a Compasso was Portolano, which also meant the accompanying chart.

The early history of the Trinity House has been lost, partly in the mists of time, but mostly in the loss of records surrendered during the Civil War. The house itself has been destroyed by fire on three occasions, the first in the Great Fire of London, 1666; then in 1714 when a fire destroyed the Custom House, most of Water Lane where the Trinity House was situated and a part of Tower Street; and again in 1940 when fire, caused by incendiary bombs, destroyed nearly all the possessions of the corporation, some of which they had owned for upwards of 300 years. Such early records as they possessed, however, and their plate, which were stored elsewhere, have survived.

The corporation received its first charter, a copy of which is in their possession, from King Henry VIII in 1514, and the probability is that a Guild or Fellowship of some sort had been in existence for some time before, possibly under the same name, as a hall and almshouses were standing in Deptford in that year.