The purpose of the S-diagrams is to give a rapid and convenient solution of the chief problems in astronomical navigation; they are especially simple for determination of altitude and azimuth. The solution is obtained without logarithms and by referring to no more than two pages of the diagrams. The diagrams are less expensive and more accurate than the Astronomisches Rechengerät (ARG), and are, without any doubt, less difficult to use than the Astronomische Rechenatlas. The method, which was recently mentioned in a paper by H. C. Freiesleben, may, therefore, be discussed here in some detail.

The name of John Dee (1527–1608) is one which every navigator, whether seaman or airman, has good cause to respect. For he was the first to try to teach unscholarly English sailors the use of the spherical triangle to find the distance and direction of some desired haven on the globe. Nor was that his only contribution to nautical science. Yet historians have treated him slightingly, dubbing him astrologer and alchemist, by which words they understand ‘charlatan’. Consequently the popular picture of him is of a servile, ignoble figure, eager to dupe the first Elizabeth and her courtiers. The acclaimed mathematician, and the ever-ready instructor are forgotten. It is true, of course, that Dee cast horoscopes, and that he hoped to find the formula for transmuting the baser metals into gold. It is true, besides, that in middle age he took to crystal-gazing, believing that he conversed with angelic spirits. Hence when in 1583 he went abroad at the invitation of the Polish Prince Lasky, a mob broke into his house at Mortlake and wrecked his library, which contained over 4000 books and manuscripts, besides scientific instruments. But by this date his work on navigation had come to an end. Yet his simple account of his meeting with the medium Edward Kelly (who was indeed a cheat) reveals him as a sincere man. Kelly at once asked to see what feats he could perform, but, says Dee, ‘I truly excused myself therein, as not in ye vulgarly accounted magic either studied or exercised. But… I brought forth to him my stone in ye frame … and said to. him that I was credibly informed that to it, after a sort, were answerable aliqui boni Angeli—certain good Angels.’ We should perhaps echo, therefore, the judgment of Disraeli—Dee's imagination often predominated over his science—but science he had.

The Rhine which has a length of about 900 km. (approximately 560 statute miles) carries perhaps a greater volume of traffic than any other river in the world. This traffic mainly consists nowadays of high-powered motor vessels varying in size between 300 and 1500 tons, and large tugs towing six to eight non-motorized barges of 500–3000 tons.

At the end of the summer of 1952, a series of proving flights were started on B.E.A. routes with the prototype Viscount airliner, the V.700 G-AMAV. One of the objectives of this proving flying was to design operating and flight-planning techniques to be used when normal scheduled services were commenced.

In the course of collecting data for a general history of scientific instruments, Dr. Price came across the manuscript that forms the subject of this volume in the Library of Peterhouse, Cambridge. It attracted his attention because of its subject matter, because it was written in Middle English, and because the date 1392 frequently occurred. As Chaucer's Treatise on the Astrolabe was written in 1391 and is apparently incomplete, it seemed at first sight possible that the Peterhouse manuscript might be a missing part of Chaucer's Treatise, which at that time was the only instrument tract written in Middle English known to Dr. Price.

The use of an airfield is controlled to a certain extent by the wind, and if the cross component of the wind on the runway exceeds a certain strength, it becomes hazardous for an aircraft to land or take off. The effect of a cross-wind component on aircraft in flight is to cause drift, whereby the path of the aircraft over the ground is inclined at an angle to the direction in which the aircraft is steered. A pilot about to land in a cross-wind must execute a certain manoeuvre to counteract the drift, otherwise on touching down the aircraft will tend to move sideways across the aerodrome, thus putting a strain on its undercarriage and perhaps tipping over on to one wing.

For the satisfactory understanding of the mechanical effects which occur in an aircraft landing in a gusty wind it is necessary to know something of the time-scale of the wind fluctuations during the moments when the aircraft is touching down. Such information can only be given on a statistical basis but it so happens that there is a body of data on the subject which may not be generally appreciated.

The word Navigation still retains the broad meaning it had in 1570, when John Dee wrote: ‘The Arte of Navigation, demonstrateth how, by the shortest good way, by the aptest Direction, & in the shortest time, a sufficient Ship, between any two places (in passage Navigable,) assigned: may be conducted: and in all stormes, & naturall disturbances chauncyng, how, to use the best possible meanes, whereby to recover the place first assigned’. But for the purposes of the Science Museum it is convenient to restrict the scope of the so-called Navigation Collection to objects illustrating the development of methods of determining a vessel's position and course. Exhibits illustrating the other aspects of navigation are placed in the Marine Engineering and Aeronautical collections.

It seems unfortunate that with the great advances made in modem navigation, the elementary and basic problems have been left unstandardized, incomplete and to a certain extent misleading, causing needless confusion to the student.

I was unable to attend the lecture by Mr. C. S. Durst on ‘The Accuracy of Dead Reckoning in the Air’, and I was, therefore, very interested to read the paper in the April Journal. There are many implications, and Mr. J. B. Parker has endeavoured to suggest some in his article.

Dr. Atkinson puts up an interesting hypothesis which I hope will not appeal to many sailors, because I do not think it offers what the navigator needs and I believe that it could be misleading. As far as concerns other plots discussed in the Journal or The Use of Radar at Sea, the criticism that they do not use all the information available is, I think, quite invalid.

I cannot subscribe to Dr. Freiesleben's thesis that until the French Revolution induced a change of mind there was a big gap between men of science and seamen. It may be, as he states, that ‘in the eighteenth century there was still a remarkable gap between scientific doctrine and practice’ and it would be interesting to know the causes if this were so, but in the sixteenth and early seventeenth centuries there was, particularly in England, a quite remarkable and organized liaison between scientists and seamen with the specific purpose of improving the art of navigation. The object, as Thomas Digges expressed it in 1579, was ‘to reduce Imaginative Contemplations to Practical Conclusions’; in other words, it was to make scientific discoveries and inventions to improve the accuracy of navigation. A few examples must suffice in the space available to support this statement.