bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early Units of Measurement and the Nautical Mile
Authors: Moody Alton B. 
Published: January 2010

To find out the origins of the nautical mile it is necessary to go back to early times, for, like so many other things, it did not spring up in full bloom in a day, but evolved by slow degrees.Early man, seeking units of measurement, logically looked about him for something in nature that he might use as a standard. For very short distances he used the width of his finger, the width of his hand, his span, the length of his foot, or the length of his forearm. As these varied between men, so the length of the derived units varied. The foot, for instance, varied from 11 to 14 inches. Even greater variation occurred in the length of the cubit, which originally was taken as the length of the forearm, from the elbow to the end of the middle finger. This unit was widely used, but varied from country to country, and was not even constant within various parts of the same country in some instances.
Course and Distance Correction from an Estimated Position
Authors: Tyrrell A. J. 
Published: January 2010

After taking a latitude at noon and obtaining a position, a course and distance to a position nearer the destination is usually required. A course and distance from an estimated noon position may be worked prior to noon and then corrected at noon by the observed latitude and morning position line, by means of a plotting chart, giving reliable results quickly and accurately.In Fig. 1, BA and CA represent the course and distance from B to A and C to A respectively. BD and EC are arcs of concentric circles with centre A; and AC = AE and AB = AD.If BD and CD are small in comparison with AB, arcs BD and EC may be considered straight lines and the figure BECD a rectangle. If the rectangle can be solved, the distance AC can be deduced from AB, i.e. AC = AB - DC or AC = AB + DC if C lies the other side of BD.
Three-star Position Tables for Air Navigation
Authors: de Jonge Joost H. Kiewiet 
Published: January 2010

This paper was written in 1946 when Mr. Kiewiet de Jonge was a student at Harvard College Observatory. Subsequent developments in astronomical navigation, particularly the publication by the U.S. Hydrographic Office of H.O.249, have overshadowed the practical advantages of the three-star position tables. But the principles of the method, which have not previously been described in print, are of sufficient importance and novelty for permanent record.In this paper we will develop a fast tabular solution of the position deduced from three ‘simultaneous’ sights. This is achieved in a novel way, through principles not generally associated with the traditional approach to the problem. The solution is based on the fact that the measured altitudes of a set of three stars uniquely define the most probable position of the observer projected on the celestial sphere.
The Correction of Astro Fixes for Precession
Authors: Sadler D. H. 
Published: January 2010

On page 268 of Volume I of this Journal, published in July 1948, A. H. Jessell called attention to a simple method of correcting fixes, or position lines, deduced from astronomical data referred to a fixed epoch, for the effect of precession and nutation since that epoch. This paper has generally been regarded as the first reference to this method, but it now appears that (as so often happens!) it was anticipated by Lieut.-Commander M. Bini, Italian Navy, in ‘Principi di un nuovo metodo per la determinazione immediata del punto nave astronomico’ (On the principle of a new method for the immediate determination of astronomical fixes), a paper presented at the meeting of the Italian Academy of Sciences on 8 November 1947 and later published in Atti della Academia Nazionale dei Lincei (Series VIII, Vol. III, Nov. 1947).An article by Bini, in which the possibilities of the method were touched upon, was also published in March 1947 in Rivista Marittima.
Astro-Fix by Computation
Authors: Collins Oliver C. 
Published: January 2010

This paper describes a method for the reduction of simultaneous star altitude observations in pairs, whereby an unambiguous ‘fix’ is obtained without reference to the dead reckoning position and without use of the intercept procedure. The method is adequate in all latitudes. An especially swift reduction is possible for the moments at which two stars are situated at equal altitudes.When position is determined by means of two simultaneous star altitude observations and use is made of a single chosen position it is possible for the Marcq St. Hilaire intercepts to be so short that they can be regarded as negligible. When this occurs the chosen position is, in effect, the true position as indicated by the observations and no further work is required for a fix. If, in such a case, it is desired to have the Sumner lines of position represented on the chart it will be possible to draw them through the chosen position. The selection of such a chosen position may be made with certainty, in every instance, by computing numerical values for the latitude and the longitude of the appropriate intersection of the two circles of equal altitudes corresponding to the corrected observations. If the entire computation had to be done after the observations were made, the labour of this procedure would prohibit its use in rapid navigation. It happens, however, that the greater part of the work can be precomputed and presented for the navigator's use in a tabular form. These data are extremely compact and are permanent except for the need of occasional adjustment for precessional effects and on account of proper motions of the stars. No almanac would be required for use with such a table if the navigator were not dependent on it for his G.H.A. Aries. No knowledge of the dead reckoning position is employed in this computation; star observations suffice to determine the position without ambiguity.
Blunders as the Cause of Collisions and Groundings at Sea
Authors: Jowitt J. E. 
Published: January 2010

Certainly genuinely unavoidable aberrations in human behaviour exist. In surface navigation, however, these momentary blunders seldom lead to fatalities such as collisions or groundings, although in shiphandling they can cause collisions when coming alongside or when manoeuvring in a confined space, but usually only of a minor nature.The examination in the R.N. Navigation School of some sixty collisions and groundings has revealed that in only two have aberrations played any significant part in the subsequent disaster. This is quite easily explained for two reasons. First of all ships at sea usually close one another or approach a danger at a comparatively low speed. Furthermore the prudent mariner reduces speed when danger exists and when the situation becomes tense. There is therefore usually time for the nature of a blunder to be recognized and for the necessary corrective action to be taken, which, if not resulting in immunity, will reduce the gravity of the incident. Sixty knots is an exceptionally high relative speed on the surface, yet this provides minutes for human reaction as opposed to seconds or even split seconds normally available in the air.
Polynesian Navigational Stones
Authors: Hilder Brett 
Published: January 2010

In this paper, a group of eight directional stones on the coral island of Arorae in the Gilbert Islands are described. The stones seem to have been used to direct canoe voyages to distant islands with the help of horizon stars en route, the stars' movements and bearings being studied and memorized in relation to the correct stone on the night before departure. They perhaps mark the site of a Polynesian navigation school which existed somewhere between A.D. 1000 and 1500. The directions given by the stones appear to have been corrected for drift due to the Equatorial Current. So far as is known these stones are unique, and have not previously been reported in print.On the island of Arorae in the Gilbert Islands there is a group of eight or nine stones which are said by the natives to have been used by early canoe voyagers to set their courses on departure to distant islands. No other such stones for navigation have been reported from the Pacific, which makes the coral stones of Arorae of unique value in the history of navigation. The stones are some of the few pieces of real evidence in the long-standing controversy on the nature and range of Polynesian navigation. The stones are called ‘Atibu-ni-Borau’ by the natives, which means ‘stones for voyages’. They have no legends or traditions which shed any light on the origin or actual use of the stones, but there are several clues available from elsewhere in the Pacific which enable the use of the stones to be determined with a high degree of probability.
An A.T.C. Survey of North Atlantic Navigation Problems
Authors:   U.K. National Air Traffic Control Service
Published: January 2010

This paper discusses a method for determining the collision risk implicit in horizontal and vertical separation standards which has been developed in the U.K. in accordance with Recommendation 7/1 of the RAC/OPS Divisional meeting. The acceptable collision risk for the North Atlantic is assessed; this must be related to airworthiness criteria and an accident rate of one in ten million is adopted. It is concluded that no immediate change in separation standards can safely be made but that the standard of navigation should be improved to allow a 90 n.m. standard; that with more data a 1000- or 500-ft. vertical separation may prove to be safe; and that longitudinal separation standards require further study. The improvement in traffic capacity which would result from changes in separation standards is also considered.This and the following nine papers were presented at the 16th I.A.T.A. Technical Conference, of which a report appears opposite. An analysis of long-range air traffic systems made by the Mathematics Department of the Royal Aircraft Establishment for the Ministry of Aviation was presented in several preliminary papers at the Conference. These studies will be described in a series of papers specially prepared for the Journal.
Automatic Star-Trackers for Long-Range Navigation
Authors: Thomas Ronald D. , Shroyer Gerald J. 
Published: January 2010

This paper describes development trends of one particular navigational technique (automatic star tracking) and its associated instrumentation methods one of which, the application of pulse code modulation theory to sensor design, is discussed in detail. Plans for the future development of this most promising concept are also included and the effects of military research and development efforts on civilian aircraft requirements are indicated. An appendix provides a glossary of special terms used.Automatic star-tracking systems have been used in military aircraft navigation for position fixing and heading correction for a number of years and the development of the equipment has been actively pursued by the U.S.A.F. since as early as 1946. Basically, star trackers are automatic devices that probe a portion of the celestial sphere for the purpose of detecting, acquiring and tracking stars or other celestial bodies. In using astronomical inputs for cruise vehicle navigation, advantage is taken of the well-known principle that sights on two or more stars when referred to the true vertical and time can be used to provide a position fix. It is the intent of this paper to review techniques used to instrument star trackers, discuss their application to long-range aircraft navigation, indicate development trends and introduce a new concept of employing pulse code modulation theory to the design of a simple, low cost automatic astro-tracker.
Some Suggestions on the Rules for Preventing Collision at Sea
Authors: Kemp J. F. , Calvert E. S. , Burger W. , Corbet A. G. , Fricker F. W. , García-Frías J. , Hugon P. , Oudet L. 
Published: January 2010

A paper by Captain J. F. Kemp under this title was published in the April number of this Journal together with some comments on these proposals. Further contributions to the discussion and a reply from Captain Kemp are printed below.In the April issue of this Journal Captain Kemp has put forward a carefully considered proposal for making the Rule of the Road more effective. His proposal is well considered because he is aware of the audacity which its careful presentation conceals; he is also careful to suggest a change in the Rules only as a basis for discussion. His suggestion is precise, for it is simply to extend Rule 18 to all encounters, or in other words to require both vessels, when crossing or overtaking, to rotate the line of sight in the normal direction as required in Rule 18.
II.—Tables for the Reduction of Astronomical Sights
Authors: Sadler D. H. 
Published: January 2010

The purpose of this lecture is to review briefly the many methods at present available for the reduction of astronomical observations, and to make suggestions for the future. The main conclusion will be that altitude-azimuth tables provide the simplest and quickest method of reducing a sight.It should be made clear that this is not a comprehensive survey setting out to examine and criticize every method; the bibliography of papers and tables (itself incomplete) published by H. Bencker in The Hydrographic Review, which contains some 1200 references, indicates that such a task would demand months of research. Attention is directed towards the principles of the various methods, and the limitations of each principle are discussed independently of the actual tables existing for the application of the method.
The Magnetic Compass: A Survey of Developments
Authors: May W. E. 
Published: January 2010

AbstractThe paper is divided into two parts. The development of ship-borne compasses is reviewed in Part I; in this section some of the difficulties due to bad siting, &c., are mentioned and certain solutions such as the use of repeating compasses and improved methods of correction are described. Part II surveys the development of the aircraft compass and shows how its phases of development have corresponded to those of the marine compass. Some recent forms of aircraft compass and methods of development are also described.
Is Forecasting Necessary?
Authors: Chichester Francis 
Published: January 2010

Twenty years ago meteorological forecasting was necessary and important to aviation. A number of factors made it so, as a short review of flying conditions in those days will show.The weather was then the dominant factor in training. The wingloading of training aircraft was then so light that a sudden variation of only 10 m.p.h. in the wind made a practice landing hazardous. Both pupil and instructor therefore anxiously awaited the weather forecast. The wind forecast was equally important to the transport pilot of 1928 when a headwind of 60 m.p.h. was likely to prevent his reaching a destination only 200 miles away.
Acceleration Errors in Astro-navigation
Authors: Parker J. B. 
Published: January 2010

Squadron Leader Bower gives some data regarding the accuracy of astronomical navigation in high-speed aircraft. No attempt was made to assess the absolute accuracy of astro-navigation, but the distance, when plotted on the chart, between pairs of sights taken on the same star was measured, with the following results.The average spread between beam shots is consistently greater than that between fore and aft shots, and it is possible that acceleration errors, which can be sizable for high-speed aircraft, are responsible for this.Errors Due To Aircraft Accelerations. Errors due to the combined effect of the aircraft's movement and the Earth's rotation give rise to errors in the position line.
The Submarine Morphology of certain Port Approach Channel Systems
Authors: Robinson A. H. W. 
Published: January 2010

Many of the major ports of the British Isles, including two of the most important, London and Liverpool, are situated at or near the head of sand-filled bays or estuaries. Their continued utility depends not only on the provision of adequate berthing facilities within the harbour area itself but also on the maintenance of a deep-water approach channel through the shoals of the outer estuary. In some cases the latter requisite is the more difficult of the two to achieve, especially where the bottom configuration is liable to considerable change over a relatively short period of time.The problems connected with a changing sea-bed configuration come within the scope of loose-boundary hydraulics, a branch of flow mechanics which has only begun to be investigated. Some success in this direction has already been achieved using scale models of specific areas but many unsolved problems remain and much remains to be done.
An Analysis of the Navigator's Task
Authors: Latham F. , Spencer J. 
Published: January 2010

The growing complexity and variety of navigator techniques and equipment, associated with a marked increase in aircraft speed, necessitates a more detailed investigation of the navigator's task. Despite an increase in the range and automaticity of navigational aids, the demands made upon him are changing their character, and are in danger of being excessively high.A detailed recording of navigator activity in flight seems the only practical approach to this problem. The knowledge gained by such a task analysis would be expected to furnish information on the following aspects:(a) Objective evidence of fatigue effects.(b) The effects of experience on the navigator's work pattern.(c) The need, if any, for the modification of training methods.(d) Equipment layout and design in relation to efficiency.(e) Practical specification of the navigator's layout.(f) Indications of specific situations which may with advantage be subjected to laboratory investigation.
Automatic Dead Reckoning Navigation Instruments for Aircraft
Authors: Pritchard H. C. 
Published: January 2010

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.
A Microwave Course Beacon
Authors: Milwright A. L. P. 
Published: January 2010

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.)
The Region of Collision
Authors: Wylie F. J. 
Published: January 2010

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.’
A Note on the Relative Wind
Authors: Hilder Brett 
Published: January 2010

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.