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This paper describes a novel function generator and multiplier using digital-to-analog conversion techniques. The device has been designed and built to supplement the existing analog computer facilities at the University of British Columbia. The function generator and multiplier, basically a digital-to-analog converter, is controlled by one ore two punched paper tapes. The device is capable of generating two independent functions specified by the input tapes, their product, and the product of an external variable and one of the tape inputs. All outputs are in analog form with a maximum range of +/- 100 volts and 0.5 % accuracy. Principle of operation, error analysis, circuit diagrams, photographs and test results are included in the paper to illustrate the operation and application of the device.

The analysis of externally pressurized, plane, oil-film pads has been mainly restricted, in the current literature, to simple pad shapes without tilt or relative sliding action or squeeze effects. As tilt can arise owing to manufacturing tolerances, or by dynamic inertial forces causing elastic deformation, it is important to assess the combined effects of tilt and sliding action in order to predict such factors as the stability of the system or the onset of cavitation. This paper presents general numerical solutions from the Atlas digital computer of the Reynolds equation applied mainly to circular pressurized pads. Results for a square pad and for an infinitely wide pad are also given. The load and location of the centre of pressure, the impedance of the pad and thus the flow rate are calculated in dimensionless form for any combination of tilt, sliding velocity, and squeeze rate. It is argued that these calculated terms are required before any dynamical problem, involving loaded hydrostatic bearings, can be attempted and before refinements of film lubrication theory can be incorporated. This paper illustrates the application of the results to dynamical problems.

The requirements of the semi-conductor industry for manufacturing devices such as transistors and rectifiers have resulted in new standards of purity for certain materials. Ultra-pure silicon is now produced commercially, with impurity levels lower than 1 part in 1010, in single crystal form of high structural perfection. This paper describes such a material, laying particular emphasis on the electrical properties, and describes methods by which it is manufactured commercially. The importance of electrically active impurities, such as boron and phosphorus, is discussed with reference to the p-type and n-type conductivities which are thereby introduced. The necessity for strict control of physical parameters during manufacture is emphasized, and methods used for the evaluation of the essential physical properties such as electrical resistivity and crystal structure are described. Some of the applications of pure silicon are introduced in this paper and the physical basis underlying the use of pure silicon in semi-conductor device manufacture is briefly reviewed.

The basic electrical characteristics of paper, mica and ceramic capacitors are compared. The interesting characteristics of the new high permittivity ceramics are discussed in detail with appropriate curves and tables. Apart from the reduction in size which is obvious due to the much higher permittivities shown by these ceramics, the large temperature coefficient exhibited by some of the ceramic bodies can be utilized for certain special applications. Experimental results of the performance of receivers under different temperature conditions in which paper capacitors have been substituted completely by the ceramics are presented. Conclusions are that ceramics can completely substitute paper capacitors with advantage. It has been sought to show that ceramics can be actually custom-built or made to the desired specifications of the circuit designer.This conclusion is particularly significant as the chances of obtaining the raw materials for the manufacture of paper capacitors indigenously are very r...

Although research on the spiral-groove bearing is now being carried out in laboratories throughout the whole world, it is still an unknown type to the practising mechanical engineer. Apart from applications in certain specialized constructions, particularly in the form of gas bearings—carbon dioxide circulators in nuclear reactors and gyroscopes may be mentioned in this connection—it has not yet found its way into practical use. On the one hand this is attributable to the lack of theoretical information about this bearing, cast in the form to which the designer is used, and on the other hand it is because little is known about its possibilities. This is a pity, since the spiral-groove bearing—particularly when lubricated with oil or grease—offers a solution to all sorts of everyday (and more specialized) problems. In particular, this full-film lubricated bearing is very promising for replacing or supplementing porous bearings and ball bearings. This paper is specially intended to describe the new practical applications which the author has found for this bearing. Reference is also made to convenient and yet accurate methods of calculating optimum designs, which are available in published form but not yet generally known. An Appendix with a supplementary method for calculating spiral-groove bearings prestressed with elastic elements and grease-lubricated concludes the paper.

The accuracy of measuring radioactivity on paper chromatograms by direct counting with a Geiger counter has been determined. It has been shown that satisfactory accuracy can only be obtained when the chromatograms are dried in still air. When chromatograms are allowed to dry in a draft, substances in the spots tend to concentrate erratically at the surfaces of the paper causing errors of up to 25% in counting.

EVERY one interested in the study of physics of the more profound kind will welcome this collection of essays by the celebrated natural philosopher, so many of which, hitherto scattered throughout various periodicals, difficult to gather together, or even wholly inaccessible to readers out of the reach of large public libraries, are yet of decisive importance for those chapters of the science to which they refer. With the two volumes now before us, in conjunction with the late publication, “Reprint of Papers on Electrostatics and Magnetism,” the collection is now completed down to the date of February, 1856. Vol. II. contains, besides, all that the author has written on the Transatlantic Telegraphs, which, according to the strict order of time, might have been looked for in later volumes. The first volume begins with a series of essays, for the most part of a mathematical nature, ranging from the year 1841 to 1850. So far as these essays relate to physical problems, their - chief interest turns on the difficulties connected with the analytic method. These difficulties were, however, even at that early period, treated by the youthful author with great skill, and under comprehensive points of view. The problems are, in part, geometrical and mechanical, referring to lines of curvature, systems of orthogonal surfaces, principal axes of a rigid body, &c. Most of them, however, deal with the integration of the differential equations, on which is based the doctrine of thermal conductivity and potential functions. The latter, as is well known, form the mathematical foundation of a large number of chapters in physics—the doctrine of gravitation, of electrostatical distribution, of magnetic induction, of stationary currents of heat, of electricity and of ponderable fluids. By treating all these problems collaterally and rendering concretely in some what in others appears in the highest degree abstract, the author has succeeded in overcoming the greatest difficulties, and we can only recommend every student of mathematical physics to follow his example. A field particularly favourable for the exercise of his powers was opened up to Sir W. Thomson by the phenomena, newly discovered by Faraday, in diamagnetic and weakly magnetic bodies, crystalline as well as uncrystalline. These our author rapidly and easily succeeded in arranging under comprehensive points of view. One great merit in the scientific method of Sir William Thomson consists in the fact that, following the example set by Faraday, he avoids as far as possible hypotheses on unknown subjects, and by his mathematical treatment of problems endeavours to express the law simply of observable processes. By this circumscription of his field the analogy between the different processes of nature is brought out much more distinctly than would be the case were it complicated by widely-diverging ideas respecting the unknown interior mechanism of the phenomena. Mathematical and Physical Papers. By Sir William Thomson. Vols. I. and II. (Cambridge University Press. 1882, 1884.)

The investigations described in the present paper deal principally with the phenomena of annealing. They form a continuation of the research described in the Bakerian Lecture for 1899 (‘Phil. Trans.,’A, vol. 193, 1900, pp. 353-377). In iron, steel, and brass these phenomena have been studied with the aid of the microscope by various workers, among whom Arnold, Charpy, Stead, and Roberts-Austen should be particularly mentioned. As a result of their labours it is well known that annealing is accompanied by a re-arrangement of the crystalline grains of the metal. Thus, when a piece of iron is strained in tension its crystalline grains become elongated in the direction of tension ; but when the specimen has been subsequently annealed by being heated to a bright red, all signs of such elongation disappear from the crystalline pattern revealed by the microscope. In fact it is not generally possible to find any definite connection between the crystalline pattern seen in the same specimen before and after annealing. In general, the pattern seen after annealing resembles that found in a similar specimen before it has been strained, but the scale and character of the pattern produced depend very much on the details of the annealing process, particularly upon the temperature applied, the time of its application, and the rate of cooling. Arnold and Stead have shown that prolonged annealing tends to produce large crystals in iron and steel. But even short exposure to a suitable temperature is well known to produce complete re­crystallisation, and it has been suggested that these changes occur at critical points corresponding to the “arrest-points” in the cooling of the metal. These arrest-points indicate evolutions of heat, and it is natural to suppose that they are evi­dences of re-arrangement of the structure of the metal.

At partial and overload conditions, radial decentralizing forces act upon the rotor of a centrifugal pump with guide vanes if the impeller is out of centre. The magnitude of these forces depends on load conditions, and the forces increase with growing eccentricity. At very small flow, these forces become non-stationary. They rotate at a considerably lower frequency than the velocity frequency and may lead to rotor vibrations. The paper discusses the effects of stationary and non-stationary radial forces, and resulting shaft deflections and vibrations, from measurements on two experimental test rigs. The paper also presents the results of research on the pressure distribution of guide vanes, carried out in air, and gives observations of flow patterns in a shallow water test rig.

IIn the Correspondence of Leon Walras and Related Papers (Jaff& 1965), William Jaffi has achieved a vast organization of experience, transforming an unstructured part of history into an intellectually and aesthetically satisfying whole. He has revealed the fundamental pattern and relation to its times of fifty years' work of a great constructive genius. The rough drafts that Walras made of his own letters, together with his papers and the letters he received, constitute an enormous mass, covering both personal and professional matters, in different locations and in different languages. From these Jaife has made a judicious selection, guided by the principle that Walras's economics is the matter of primary interest for these volumes. Guided by the same principle, Jaff& has also included letters that reveal the way in which Walras's social class, education, personal circumstances, and intellectual, political, and economic times influenced some aspects of his work, particularly his positions on economic policy. Since the letters were written long ago by many people, and cover many topics and half a century in time, Jaff& has provided annotations to establish a meaningful context for them, and has prepared excellent indexes. His work makes the Correspondence a fine research tool. It is a rich and usable source of materials for those who want to understand Walras and economics in the second half of the nineteenth century. Jaff6 explains allusions to historical and literary events, presents biographical and bibliographical information, makes cross-references, and summarizes and quotes the works and papers of Walras and his correspondents, so that the letters and the notes clarify and complement each other. In the annotation, Jaff6 displays the editorial brilliance, the indefatigable and meticulous scholarship, and the detailed knowledge of Walras's work that we have come to take for granted from him. The previously unpublished papers are significant as additions to our knowledge of Walrasian and

THE collection of Cely papers in the Public Record Office, London, is a unique source of information on the lives and business activities of a group of English wool merchants in the last quarter of the fifteenth century.' The family was founded by Richard Cely the elder, who appears as an established member of the Calais Staple in 1449 and died in January 1482. His sons Richard and George acted in partnership from 1476 until the death of George, the younger of the two, in June 1489. By the time of George's death the brothers, who were much less cautious businessmen than their father, were hard pressed by creditors, and Richard may well have been disconcerted to find that his brother's will made no specific mention of any repayment of his share in their joint trading debts.2 George apparently intended his widow to be sole executrix, though the matter is phrased with some ambiguity: "I make and ordeyne hir my sole Executrice for the substaunce that I have comyn by hir."3 His widow, who promptly remarried, taking as her third husband Sir John Haleghwell, a Devonshire gentleman on the make, disputed Richard's claims on the estate, and the matter was taken to Chancery. Probate of George's will was not finally granted until 1497, when administration of all the estate apart from the widow's jointure was given to new executors who included Richard's brother-in-law Avery Rawson, a principal creditor of the firm. Richard himself did not see the case to an end, as he died in 1493, leaving his own widow to carry on the suit and to make the final settlement with her brother and other creditors. The court of Chancery took any papers that might relate to the brothers' partnership, together with a good many private letters that did not. In accordance

At the very urgent request of the late Dr Sang, who regarded the above paper as one of his chief contributions to science, I brought before the Council of the Society the question of its publication. From the Minute-Book of the Ordinary Meetings, I find that it was read on the 20th February 1837, though it is not mentioned in the published Proceedings of that date. On 21st July 1891 the Council finally resolved that the paper should be printed in the Proceedings “if otherwise found desirable.” The reasons in favour of printing it seem to outweigh those which may, readily enough, be raised against such a course.

At the Central Hall, Westminster, on Tuesday and Wednesday, October 15–16, the Corrosion Convention organised by CORROSION TECHNOLOGY will take place. Papers on a wide range of aspects of the corrosion problem will be delivered by authorities from industry and research. Delegates to the Convention will receive pre‐prints of all the papers, but for the benefit of readers who cannot attend we print below abstracts of a selection of the papers which are available as we go to press.

A method is described for making a projection drawing from any point of view in which the drawing is set out directly from the dimensions of the object without the use of intermediate plans and elevations. Seven key figures are given with the necessary numerical factors which give directly the proportions for forty-two points of view. By the use of square ruled paper and these figures, aided by the slide rule, figures may be drawn in which the dimensions are found by means of the rulings on the paper only, so that scales of length are not needed. An example of the use of the method is an illustration of two pentagonal dodecahedrons, one that of Euclid and the other that of a crystal of iron pyrites. The last part of the paper deals with the solution of the spherical triangles on which the method depends.

Measurements of the penetration tensions in paper of a series of creosotes distilled from a single coal tar are reported (the penetration tension being the product of the surface tension and the cosine of the contact angle). It is found that these data conform to two equations: one, previously developed by others from theoretical considerations of the effects of variation in size and distribution of capillary pores upon the theoretical equation of flow, the other, an empirical relationship which is less difficult to apply in more practical problems where many data must be analyzed. The creosote‐paper contact angles are shown to be zero or extremely small. Possible errors in the paper strip method are discussed and the importance of calibrating each strip with a reference liquid is demonstrated. The failure of Washburn's equation, which has received considerable attention in the field of fibrous penetration, is shown to be due to the neglect of the hydrostatic head term. The penetration tensions of these c...

Continued development work at University College, Dublin, on the variable compression ratio, two-stroke diesel engine, discussed in earlier communications to the Institution, has demonstrated the ability of this unique design to combine long service life with high specific output. The present paper summarizes the current status of the programme after four years' work. The basic design philosophy adopts a two-stroke cycle and exhaust gas turbocharging to obtain high specific output, and an automatic variable compression ratio mechanism to ensure long service life by controlling piston loads. The paper gives details of the variable compression ratio mechanism including the specification of the various components of which it is comprised. Test results show the response rate of the mechanism relative to changes in engine operation. Results are also given for the engine as operated with various air supply blowers to give characteristics suitable for specific user applications.

A windowless tube has been developed which can be used to detect tritium activity on paper, glass, or aluminum. The tube is of glass, with a nichrome anode and a copper sulfide coated copper cathode, and utilizes a stream of helium saturated with alcohol. This device is convenient for detection of tritiated compounds in paper chromatography.

Concentrations of toxic metals can be determined in a drop of blood, such as might be obtained from a finger-prick, by spotting the blood onto filter paper, drying it, and then burning a standard size disc punched from the filter paper in an atomic absorption spectrophotometer. Results for lead, cadmium and zinc determined in this manner compare favorably with accepted macro-methods of analysis. The advantages of this procedure, namely the ease of specimen collection and the simplicity of the analysis, may make this the method of choice in biochemical monitoring for trace metal absorption by workers.

This paper shows firstly how the choice of base stock reduces apex-seal wear. Results emphasize the influence of volatility, and particularly of the quantity and viscosity of the residue after heating. The second part (section 3) concerns pre-ignition. Testing was difficult, but a connection was found between the ash content of the oil and severity of pre-ignition. Testing of anti-wear formulations for pre-ignition was found to be necessary. The third part (section 4) is devoted to engine smoothness, which must not be confused with pre-ignition. Spark plugs and mixture strengths are the most important factors, fuel probably having only a secondary effect.

Throughout my years of work as an information scientist I have been plagued by a personal and professional sense of doubt with respect to the field. A central theme of every conference that I have attended related to: “What is information science?” Or “Is information science a science?” In this paper I hope to take these questions head on. I must begin by saying that I do take information science seriously as a science. I see it as the quest for understanding of the nature of information and man's interaction with it. That we lack so much in this quest for understanding is the greatest challenge of the science. I intend to explore the tradition, or world view, bearing on the scientific study of information. The currently prevalent world view is the scientific tradition which extends from the Enlightenment to the present. I also intend to look critically at what I perceive to be the premises underlying most of our. current efforts to understand the phenomenon of information. The criticism will by necessity be speculative. I intend to stick my neck out, not because I can prove my assertions, but because I believe these ideas must be discussed.

Relates a fascinating, but somewhat sordid story of the circumstances surrounding the publication of Messages and Papers of the Presidents in 1990. The role of Richardson as chairman of the House Committee on Printing and as compiler of the set of 10 volumes is described in absorbing detail. His attempts to privately copyright a commercial edition and to make money from what was originally an official compilation were devious at best and are described in a series of incidents which placed Congress in a false position. Ainsworth R. Spofford, as retired Librarian of Congress and as editor of the index to the set, was an unwitting accessory to the strange events leading to the commercial exploitation of these government documents by Richardson and his publisher. The authors point out that librarians continue to lend their names to publishing projects of dubious merit and contribute to their exaggerated claims.

Using the Frankel-Young method, fast estimation of the potential distribution for a microstrip structure is obtained when an accelerating factor /spl omega/ is introduced in the finite-differences (relaxation) method. It is possible to calculate such a factor by an iterative technique, but the time of computation needed to find /spl omega/ annihilates the theoretical gain. In this short paper, the authors present a method which gives an analytical expression for /spl omega/. The realistic case examined here, as an illustration, is that of the suspended microstrip couplers for which odd and even impedances are the interesting parameters. Given an analytical expression for /spl omega/, the overrelaxation method appears as a very powerful and attractive method for finding the solution of any type of microstrip structure.

Reviews the background and current operations of the State Paper Room (now the Official Publications Department) of the Department of Printed Books of the British Museum, which has recently been reorganized as part of the new national library organization called The British Library. There is detailed discussion of its processing, reference, and exploitative functions. There is detailed discussion of the development of extensive exchange arrangements with other foreign documents, which have been continued and augmented and constitute the main reliance for current additions at the rate of 90,000 items per annum. The British Museum possesses one of the oldest, largest and most comprehensive document collections in the world, especially strong in publications from Britain and its associated states. These have been acquired by the four methods of copyright, donation, exchange and purchase. The large holdings are treated as a coherent unity, maintained by a unique classification scheme, and by the methods of registration and interim cataloguing. These allow rapid application by clerical staff, making possible the flexibility and speed necessary in handling material of this nature.

IN order to obtain a good separation in filter paper chromatography, the size of the spot of liquid applied to the paper must be small, which often necessitates repeated, time-consuming applications of material. Methods have been evolved with the purpose of having spots or a. band laid down automatically by a burette1,2. There still seems to be a need, however, for a technique by which a larger volume of fluid can be deposited quickly and simply, yet permitting small-sized bands or spots for good separation.

FILTER paper is frequently used as a means of supporting radioactive substances, such as proteins or the effluent from a column, for counting in liquid scintillation counters. While this is satisfactory for most isotopes in common use, the efficiency of counting tritium is undesirably low, being a fraction of the efficiency obtainable with tritiated toluene. Glass fibre paper, however, has been found to allow a much higher counting efficiency, approaching the theoretical maximum.

IN a recent communication by Proom and Woiwod commenting on circular paper chromatography, they state: "although the method is admirable for the separation of two or three substances, it is not a satisfactory substitute for large–scale paper chromatography in the separation of more complex mixtures such as protein hydrolysates".

1. The 60 Hertz and impulse electrical strength of oil impregnated polyamide paper is as good as that of high quality electrical grade kraft paper and better than that of rope-kraft paper used as conductor insulated. 2. The 60 Hertz dissipation factor of polyamide paper in oil increases moderately with increasing temperature. 3. Based on burst strength and tensile strength retention, the thermal stability of the polyamide paper is substantially superior to that of cellulosic paper when aged in oil or askarel at 150°C and 175°C. 4. Polyamide paper showed little or no degradation after extended life tests in distribution transformers. 5. Polyamide paper with its superior mechanical properties can better withstand manufacturing operations in production than can cellulosic papers. 6. Based on life test results the polyamide paper will permit the design of transformers with higher operating temperatures and greater overload capacities than can be obtained using cellulosic paper.

AN automatic scanning technique employing a Geiger–Muller tube for the location and estimation of radioactive substances separated on unidimensional paper chromatograms has been described1. The application of this technique to two-dimensional chromatograms is tedious because a large sheet of paper has first to be cut up into the equivalent number of unidimensional strips and each strip scanned separately. To obviate this difficulty, an alternative technique to the conventional form of two-dimensional paper chromatography has been successfully developed for the application of two or more solvent systems to the same labelled mixture.

Research on the dielectric strength of high-voltage cables can be very conveniently carried out on "models". Either plate or cylindrical capacitors can be used for this purpose. This paper reports the results of many tests both at power frequency and at impulse, which have the purpose of investigating the separate and combined influence of a series of different factors affecting the dielectric strength of a fully impregnated paper insulation as used in high-voltage cables. The main factors investigated are the following: Paper impermeability, Paper density, Paper thickness, Oil viscosity, Oil pressure, Electrode surface shape, Electrode surface nature, Butt-space thickness, Butt-space position with respect to electrodes. Butt-space relative position. The paper ends with a comparison of results obtained on models and on actual oil-filled cables, which show a good agreement if certain assumptions are taken into consideration.

IN recent studies on the paper electrophoresis of carbohydrate compounds, we have found that replacing the cellulose filter paper by paper made from glass fibres1 greatly facilitates the identification of sugars and their derivatives, especially those which are difficult or impossible to detect on cellulose paper.

IN this laboratory the technique of circular paper chromatography has been modified in that small rectangular strips of filter paper are used rather than filter paper disks. This has resulted in the separation of compounds as round compact spots rather than circular bands. In addition, a combination of a horizontal solvent flow with an increase in developing temperature has resulted in a rapid increase in the mobility of the developing solvent coupled with a desirable increase in resolution.

An analogue technique is described giving good approximate solutions of the biharmonic equation. The method uses two plane sheets of conducting paper linked by an array of resistors. The technique is applied to problems involving the slow flow of a viscous fluid past uniformly spaced parallel fibres. Calculated values of the Kozeny constant from the results show much better agreement with the practical and theoretical values than those derived from previous analogue solutions.

Summary The performance of electrical circuits incorporating three-electrode valves is affected seriously at very high frequencies by the times of transit of the electrons between the various electrodes. It is shown in the following paper how these times may be determined for any valve with a positive potential on the grid and any potential on the anode. It is also shown how the velocity of emission of the electrons from the cathode may be taken into account.

A practical system for translation of information coded on punched paper tape to a matrix on a photograph is presented. The information here consisted of stereo random brightness fields; however, the system should be applicable to any three-dimensional information. The matrix is developed by slow digital scan of an intensity (ten levels) modulated oscilloscope and is photographed by a camera on time exposure. The system requires 166 seconds to produce each 10 000 element matrix and hence cannot be used for on-line work. However, for the researcher who can tolerate this limitation, the system's low cost, simplicity, and good resolution (better than 100 elements per inch) should prove attractive.

This paper covers General Cable Corporation's development and testing of a 500 KV high pressure pipe type oil filled cable. It also covers the installation of a sample length of this cable at the Edison Electric Institute test site at Waltz Mill, Pennsylvania.

The development of digital programs for predicting the performance of multi-cylinder, turbo-charged diesel engines, and the temperature distribution in engine components is described. The performance program incorporates the relatively simple ‘filling and emptying’ method, with the turbo-charger compressor and turbine as boundary conditions, to calculate transient gas conditions. In the second part of the paper a description is given of the metal temperature program assumptions and use, including the deduction of the surrounding fluid conditions. The accuracy and limitations of the performance program is demonstrated by comparing predictions and measurements on an experimental 2-stroke single cylinder diesel engine operating under simulated turbo-charged conditions. The practical applications of the programs to medium speed 2- and 4-stroke engines are illustrated, and the economics of their use as a design aid are discussed.

A study has been made of diesel exhausts, and this paper relates the essential parts of what was found. Exhaust pollutants and their physiological effects are examined, and the steps taken by the National Coal Board for the protection of personnel and against dangers from explosions and fire are considered. The action taken to comply with statutory exhaust gas checks is given, and the necessary minimum ventilation of tunnels to acceptable standards is detailed. Other aspects of exhaust fume control, including that in confined spaces above ground, are dealt with. Finally, methods of treating diesel exhaust emission are suggested.

Although many scaling laws are available for the assessment of prototype performance from tests on small-scale models, the discrepancies between them are wide and varied. This paper considers the effect of individual components and shows that it is unlikely that any single law can be applied to pumps as well as turbines, to pumps of different specific speeds, or to pumps of the same specific speed but designed to differing philosophies. It is proposed that more information pertaining to scaling laws can be acquired if pumps running at different speeds and in different fluids are studied.

This paper is concerned with the machinery for the launching of aircraft from and the recovery of aircraft on to the flight decks of aircraft carriers. The machinery to do this is hydraulic—except for the working fluid of slotted cylinder catapults, which is steam—and is required to control the application of large amounts of energy, in a short period, precisely in accordance with a set programme, with complete consistency and absolute reliability. Hydraulic machinery has successfully met all these requirements for fifty years, being developed and revised to keep pace with the increases in the performance of carrier-borne aircraft. The major developments—catapults for launching and arresting gear for recovery—are described, together with some items of ancillary equipment that demonstrate the versatility of hydraulic machinery. Simple principles have always been used, but the designs have always made use of the most advanced techniques of hydraulic engineering.

In this paper, both Hooke's joint and the modern ball type constant velocity unit are considered. Methods by which the specific capacity and life endurance of a joint may be estimated are described. A method of calculation to select a suitable joint for automotive purposes is discussed.

Previous work on non-steady flow in exhaust systems has shown that the method of characteristics can be used to predict the flow conditions to a high degree of accuracy. In these calculations the pressure at the inlet port or valve was considered to be constant. Recent work on the effect of pulsating flow on centrifugal compressors has shown the importance of considering non-steady flows in the inlet systems of supercharged engines. Predictions of the non-steady flow in inlet systems, usually based on acoustic theory, have only been accurate in particular cases. In this paper the method of characteristics has been applied to the study of non-steady flows both in the inlet and exhaust systems of internal combustion engines. Comparisons are made between the calculated and experimental results obtained on a multi-cylinder pulse generator. Tests on both single- and two-cylinder units were carried out and measurements of the inlet pipe pressure, exhaust pipe pressure, cylinder pressures and temperatures, and inlet and exhaust mass flows were made. Comparisons between the theoretical predictions and the test results were extremely good; in all the cases the pressures were in close agreement. The inlet predicted mass flows were all within +9 and −4 per cent of the measured flows, the standard deviation being 3·1 per cent. The exhaust mass flows were all within +8 and −12 per cent of the measured mass flows, the standard deviation being 4·3 per cent. It was considered that the method gives reliable predictions of the flow processes in internal combustion engines.

Following a preliminary introduction on the necessity for fuel and control systems, it is proposed to deal in some detail with the requirements of modern gas turbine engines from the point of view of both pumping of fuel and the control. In general the paper deals with aircraft type systems. Over the last 20 years specifications have been increasing in size and the need for the additional requirements will be discussed in relation to the various types of engines. Considerations of control for two- and three-shaft engines for both civil (subsonic and supersonic) and military use are covered, as also are the somewhat different requirements for helicopters. In addition to main engine control, the effects of reheat, supersonic nozzles and variable engine geometry will be discussed. Reference is also made to the increasing severity of environment on high speed aircraft. Following this, the problems of pumping are considered and a review of the types of pumps available is made comparing their relative advantages and disadvantages in relation to the application, and indicating the general trends in this field. On control systems the types of control available will be discussed including hydromechanical, electric and fluidic, and the basis on which the optimum choice can be made for any particular engine will be dealt with. The requirements for control, both for steady running and limiting will be explained, and once again a typical example of a control system is briefly described.