Although the use of bisectors to select the most probable position determined from astronomical observations is well known, the system seems to have received insufficient recognition in current navigational literature. In what follows an attempt is made to assess the problem practically.

Powered research ships are the basic vessels from which the science of oceanography is conducted. For the investigation of certain surface water problems, however, a large, powered vessel is not the most suitable platform, for, while affording ample accommodation and working space, she may have fundamental faults. Her deck may be far above sea-level so that in bad weather direct observation of marine life is impossible. More important, her mere presence may alter the very characteristics, both physical and biological, which are being studied. Thus her hull, rolling, pitching and threshing in a seaway may appear to some animals as a fearsome intruder. The throbbing of her propeller sets up low-pitched vibrations powerful enough to alert the fish for miles around. The sea close to the engine room becomes warmed and to it is added hot water from the condenser. There is violent water mixing by the bow wave. These factors in combination effectively alter both the sea temperature and the thermal stratification. The ship's wash, thrown away from the sides, may set up a heavy cross sea which distorts the shape of nearby waves, particularly in regard to their steepness and height.

Dr. Atkinson here proposes a type of radar plot which was not actually considered in the Institute working party's recent report. It would be useful to have some comment, particularly from sea, on the effectiveness of this type of plotting.—Ed.

The current discussions on radar plotting at sea appear to have rather overlooked one plot which may have quite important advantages: this is the pure time-distance plot, ignoring bearings almost completely. One would use ordinary squared paper (say quarter-inch squares or some similar coarse mesh), with distance increasing upwards, time increasing to the right, and both scales permanent ones; pre-printed scales would be useful, but not essential of course, and one might suggest an inch to a mile and an inch to four minutes.

A country that frowns on rich men must be content to let its rare books cross the ocean. Certainly it will lose all those which make no appeal to the literary man, and those to which the devotee of ‘pure’ science is indifferent, since these are the two groups who might be consulted before such a transference, or whose protests would be listened to. Hence it is that, because only a tiny minority has as yet been interested in the crude beginnings of applied science and technology, a discerning American member of the Institute, Mr. Henry C. Taylor, has formed a collection of about one hundred and fifty books which tell the story of how skippers and pilots were taught to set course and make port during the Great Age of Discovery and Colonization. Nearly half of these books are in English, and this is understandable, for although the pioneers of the new methods of navigation were the Portuguese, the English sailor took pride of place after the defeat of the Spanish Armada. Mr. Taylor appears at one time to have been satisfied with the breezy statement of Captain Smith of Virginia in 1626 that the seaman was sufficiently equipped if he had his Almanack, his Waggoner, a manual or two, and knew a good instrument-maker like Master Bates on Tower Hill. But one book leads to another, and, having got together these half-dozen books, he began to study them.

We were taught at school that a stone which is thrown forward in a horizontal direction from the edge of a cliff will describe a curved path which is a parabola. The path is in fact an ellipse—but that is not the only thing we were taught at school which turned out to be erroneous in after life. This error arises from the elementary assumption that all vertical lines are parallel; but the vertical in fact is the direction of a plumb line, and all such lines converge towards the centre of the Earth. With a small initial velocity the stone will describe a small ellipse which intersects the surface of the Earth, but with greater speeds the ellipse becomes larger, until it finally clears the Earth completely and returns to the thrower. Although the stone is now circling the Earth, it is still ‘falling’ freely in a gravitational field, and from this point of view all such orbits are referred to as ‘free orbits’, the stone being in a state of ‘free fall’.

In October 1954, Aries IV, a Canberra aircraft from the Royal Air Force Flying College, made the first flight by a British jet over the North Geographical Pole. This paper describes the navigation aspects of that flight, together with a later series of training flights for which it was a preparation.

For several years it has been the practice for navigator students at the Royal Air Force Flying College to carry out high-latitude flights as part of the normal syllabus of training. Hitherto only piston-engined aircraft have been used, but in 1954 it was decided to extend the scope of activities to include Canberras, the first flights to take place in December of that year from an airfield in northern Norway. A preliminary survey was necessary to confirm the practicability of the proposed navigation technique under actual conditions, and it was agreed that this should take the form of a flight towards the North Geographical Pole. A further object of the survey was the selection of a suitable operating base; the choice lay between Bardufoss and Bödo.

It is a notable compliment to the captains and masters (particularly to the masters) who served Elizabeth I that she lost no important ship of her Royal Navy by stress of weather or by stranding throughout her long reign. She lost two ships to the enemy for both the Jesus of Lubeck and the Revenge surrendered to superior Spanish forces after hard fights. The Revenge was a moderate-sized ship or galleon of 450–500 tons, described by Monson as being ‘low and snug in the water, like a galliasse’. She was built at Deptford in 1575–7 and carried a ship's company of 250 men and an assorted armament of 38 guns, large and small. Although of middle size, she was Drake's flagship in the Armada campaign and again in the voyage to Lisbon in 1589. She was Frobisher's flagship in 1590 and Grenville's in 1591, when she was captured in epic circumstances and soon after capture overwhelmed in a hurricane with her prize crew. In August 1579, when she became the flagship of Sir John Perrot in a voyage to Ireland, she was a new ship. Her master was John Gray, who was still her master under Drake in 1588. The Revenge was considered an unlucky ship. Both Sir Richard Hawkins and Monson list the tale of her misfortunes and Hawkins writes of her : ‘The Revenge, which was ever the unfortunatist ship the late queen's majesty had during her reign; for coming out of Ireland, with Sir John Perrot, she was like to be cast away upon the Kentish coast’. He blames her name for this ill-luck, for revenge should rightly be taken by God alone and not by man.

A series of overlapping photographs taken from a aircraft flying straight and level can be used to indicate the strength and direction of the wind, by noting the displacement on successive prints of the centre of the photograph, which is assumed to represent accurately the position of the aircraft at the time the photograph was taken. The method has the advantage that an almost continuous record of the wind can be obtained; it can be used over virtually any ground surface (though not over the sea) and the results of a long flight can be fairly easily and rapidly assessed. No detailed identification of the ground on a map need be made.

In order to obtain some experience of problems that were likely to be encountered in the operation of the Comet III across the North Atlantic, B.O.A.C. decided early in 1954 to conduct a daily ‘paper’ operation between London and New York. The aircraft was planned to depart from London at 1000 G.M.T. each day. It was felt that the production of operational statistics on the basis of a daily operation in this way would enable the Corporation to compile useful information on such vital subjects as elapsed times, payload capacity, fuel uplift requirements, the frequency with which particular routeings were likely to be used and the adequacy of existing meteorological telecommunications and air traffic control services. In order to obtain the basic meteorological data for planning flights it was necessary to enlist the cooperation of the London Airport Meteorological Forecasting Unit and their most helpful cooperation played an important part in the results achieved.

The past few years have seen a great increase in the amount of traffic at airports throughout the world. Today a rate of thirty aircraft movements per hour is by no means unknown and sixty movements per hour can realistically be forecast for the near future.

Although only a small percentage of the world's total tonnage is involved, the number of collisions which take place at sea each year is large. There must also be a fairly large number of ‘near misses’, and, daily, officers have to consider the implications of situations which could give rise to collision. It is by no means certain that all seafarers put the same interpretation on the Collision Regulations or on such phrases as ‘the ordinary practice of seamen’, ‘ample time’ &c. Indeed, with some 1600 to 1850 collisions each year, it is almost certain that they do not.

A number of members have been invited to contribute to a general discussion on the value of meteorology to navigation. It is hoped to follow Mr. Williams' contribution with others dealing with different aspects of the subject.

Years ago there was weather in which birds and airmen alike walked. Now, although operations through particular airports affected by below-minima weather may be interrupted, airline services are rarely cancelled because of weather en-route. As aircraft tend to fly faster and higher, and navigational aids slowly improve, the weather information required by the short-range operator tends to be conditioned by the question: Can my aircraft operate through airport X at time T? The long-range operator is still interested in two other questions: What route will give the most favourable component, and What is that component? Having the meteorologist's answer to these and other, less vital, questions, the operator plans his flight on the assumption that the forecast is quite correct and equips and fuels his aircraft on the assumption that it is wholly false. The operator has learned to compensate for the errors of forecasting; possibly all the airline accidents in recent years in which unexpected weather deterioration played a major part could have been avoided with sound airmanship. The most realistic way, therefore, to consider the value of forecasting to airline operation is to attempt to evaluate the cost to operators of the measures they take to protect life and equipment against forecast error and speculate on what would happen if no forecasting were attempted.

Historians of the mariner's compass (particularly those of the last century) have introduced into the literature of the subject a number of statements which can be shown to be incorrect, or at the least to be extremely doubtful. Unfortunately it is just these ‘facts’ which have been seized upon by later historians and appear in one authoritative book after another. I have myself fallen into one stock trap or another in the past.

E. G. R. Taylor's interesting and noteworthy book The Mathematical Practitioners of Tudor and Stuart England shows that navigation was at first based on the experience of practitioners; men of science were too remote from practical requirements. There was a big gap between what interested them and what the seaman could understand and apply.