bluuebunny/crossref_metadata_2025 huggingface dataset:
Alloys Research Committee: The Work of the Alloys of Iron Research Committee
Authors: Desch C. H.
Published: October 2007

The Alloys Research Committee of The Institution of Mechanical Engineers began its work in 1890, and from 1902 onwards the investigations were conducted in the National Physical Laboratory. The Eleventh Report, published in 1921, dealt very fully with the light alloys of aluminium. At that stage it was decided that further research should be devoted to the alloys of iron with the object of determining the fundamental nature of the alloys of iron with various metals and non-metals to serve as a basis for a more systematic knowledge of the steels used in practice. The investigation has comprised the construction of equilibrium diagrams using thermal, microscopical, X-ray, and other physical methods. Iron being more sensitive to the influence of minute quantities of impurities than most other metals, it was necessary to prepare very pure iron as the basic material. Since 1921, the alloys of iron with oxygen, phosphorus, silicon, chromium, and manganese have been studied. As all the alloys are of high melting point, many new laboratory methods have had to be developed, the technique of experiments at high temperatures becoming more difficult the higher the upper limit is raised. In the course of the research, therefore, it has been necessary to prepare new refractories and to design special forms of apparatus in order to avoid contamination. The paper contains a summary of the results obtained in the course of the work, and it is shown how these bear upon the improvement of steels for structural and engineering purposes. The investigation is being extended to other elements, and ultimately to the influence of more than one solid element when present simultaneously in the alloy.
The Evaluation of Coal, with Particular Reference to Small Coal for Steam Raising
Authors: Grumell E. S.
Published: October 2007

It is generally recognized that the sale and purchase of coal for steam generation on the basis of its calorific value would be more rational than the present methods. In the paper the advantages of the calorific value basis are briefly discussed, and reasons given for its relatively slow development. The non-uniformity of industrial coals makes it difficult to assess their value except in relatively large quantities. This has an important bearing on the selection of coal by the short boiler-trial method. Apart from the technical difficulties of attaining a reasonable degree of accuracy in a short boiler-trial, there must always be a doubt as to whether the sample tested was really representative.

An alternative method of evaluation is described which enables larger and more representative quantities of coal to be examined. This method is based on accurate sampling and analysis, and is claimed to be less liable to error. At the same time it permits a greater number of types of coals to be investigated, thus giving the purchaser a wider choice, and increasing his knowledge of coals. In addition, the author provides a basis of control for subsequent deliveries. It is, in any case, strongly recommended as a check on any other method.
Achievements in High Specific-Speed Water Turbines
Authors: Fulton A. A.
Published: October 2007

The steady increase in the capacity of generating sets created a demand for the high specific-speed turbine which was met by several experimenters. “Specific speed” is the speed at which a turbine will run under unit head when developing unit power, and nowadays a “high specific-speed” water turbine denotes one having a runner of the propeller type and a specific speed between 100 and 230 r.p.m.

Difficulties were encountered in the development of propeller turbines, especially in connexion with cavitation. Laboratory tests and the use of visual study methods have played an important part in the solution of these difficulties. The method of fixing suction head in conjunction with laboratory test results is explained, and a comparison is made between the various forms of suction tube in use. Much work has been done to overcome the effects of localized cavitation, and stainless steel has been found to be very effective, especially when runners are cast entirely of that material.

A method of operation has been developed to dispense with the use of inlet sluice gates in large machines. Several methods in use for operating the movable runner blades are described. The introduction of the high specific-speed turbine has led to a large increase in the number of automatic stations. The great size attained by these turbines has entailed the construction of equally large generators, the development of which has had its own problems.
The Loss of Heat by Natural Convection from Parallel Vertical Plates in Air
Authors: Carpenter L. G. , Wassell H. C.
Published: October 2007

The variation with height, spacing, and temperature excess above ambient air, of convective loss per unit area, averaged over the whole surface of a plate, has been determined experimentally for both tall (4-foot) and short (1 ft. 4 in.) plates.

In the case of tall plates, the heat losses from the upper, middle, and bottom portions have been determined separately, so the effect of spacing and temperature excess on the relative efficiency of the various parts of a plate is known.

Some observations have been made on the effect of prolonging the plates upwards by means of a chimney of wood.
Notes on Roll Failures with Reference to Chilled Iron Cast Rolls Containing Chromium and Molybdenum
Authors: Caswell J. Selwyn
Published: October 2007

The details of some remarkable fractures of chromium-molybdenum rolls are given in this paper, and they are compared with the fractures usually associated with ordinary chilled iron rolls. Some interesting and informative foundry experiments with chromium-molybdenum rolls are described and illustrated by photographs.

The probable causes of fracture of the chromium-molybdenum rolls are discussed in the light of the quality and structure of the iron, the design of the rolls, and the effect of thermal stress. It is suggested that the causes of failure were (1) low strength of the iron, resulting from excess of chromium, (2) the defective design of the roll wobbler, and (3) the thermal stresses set up in the rolls during service. Detailed consideration is given to the effect of the wobbler design in preventing the free contraction of the roll after casting. It is suggested that the interference set up had produced definite planes of weakness in the rolls.

Particulars of an unusually long life of an ordinary chilled iron roll are given together with a comprehensive analysis of the iron in this roll.
The Care of Modern Steam-Generating Plant from the Water Side
Authors: Glinn R. J.
Published: October 2007

The condition of the metal of the boiler units of the modern steam-generating plant is affected by the condition of the water which is used as feed. Compared with typical figures of a few years ago, the working pressure and the degree of superheat of the steam have increased, in addition to the rate of evaporation resulting from improved methods of firing and combustion. These factors influence the effect of the water on the metal parts.

An examination is made of various feed water circuits and of the methods of treating and controlling the quality of the feed and boiler water. Various examples are given of the difficulties which can occur, due to incorrect treatment and control, both in respect of scale and corrosion troubles. The causes of such troubles and the means for overcoming them are also considered. Instances of failures of economizer, boiler, and superheater tubes are given, and additional reference is made to the causes and effect of caustic embrittlement of the metal of the boiler. By careful attention to definite rules for the correct treatment and control of feed and boiler water conditions, steam-generating plants will keep in satisfactory condition under the exacting influence of the high pressures, high superheats, and high ratings of the present day.
Worm Gear Performance
Authors: Merritt Henry E.
Published: October 2007

The paper represents an attempt to establish a basis upon which the load-carrying capacity and efficiency of worm gears may be predicted. It forms a supplement to a forthcoming British Standard Specification.

The requirements of a worm thread profile are briefly considered and the use of the involute helicoid as a basis of worm thread design is recommended. The geometrical properties of the involute helicoid are discussed and a simple method of determining the zone and lines of contact is given.

On a theorem on the curvature of tooth profiles as basis, the relative curvature of worm threads and wheel teeth is determined. A method of comparing the stress conditions between lubricated surfaces making moving line-contact is presented and its application to the determination of the allowable loading on worm gear teeth results in simple formulæ. A comparative method of determining wheel tooth strength is also given.

An experimental apparatus has been developed for investigating the friction between surfaces in lubricated line-contact, and some of the results obtained therefrom are described.

The relation between the results obtained from rolling and sliding disks and from actual worm gears is discussed, and average values of the coefficient of friction which may be used in design are given.
The Bend Test, and Its Value as a Guide to Ductility
Authors: Schuster L. W.
Published: October 2007

Considerable scientific study has been devoted to the tensile and other forms of mechanical test, but the bend test, though one of the most useful, has escaped any such treatment, with the consequence that it is, as often as not, carried out in a slipshod manner that leads to fortuitous results and gives little or no knowledge of the properties of the material. The paper correlates the ductility shown by tensile and bend specimens, and enables the ultimate performance of a bend specimen to be foretold with reasonable accuracy. It gives a large amount of data that may be found useful in preparing specifications.

Owing to the complexity of the problems involved in plastic bending, the subject does not lend itself to theoretical treatment, but by the use of empirical data very simple formulæ can be derived, sufficiently accurate for applying to commercial tests and correlating various test conditions with one another. The results given by the more usual forms of bend test are analysed, and the special characteristics of the tests are described. Several methods of carrying out tests are shown to be faulty and to lead to unnecessary straining of the metal; consequently widely different results are obtained by different operators working to the same specification. Suggestions are given for designing the most suitable apparatus and for modifying methods of test, to improve results and to overcome inconsistencies.

The special problems involved in making a bend test on a welded joint are also discussed, and recommendations for tests are made. The ductility developed by such a test is also correlated with the ductility shown by a tensile test on the weld metal itself.
Relation between Theory, Experiment, and Practice in Journal Bearing Design
Authors: Haslegrave H. L.
Published: October 2007

The first section of the paper is devoted to the correlation of experimental and theoretical research on journal bearings embracing the angles of 360 deg., 180 deg., and 120 deg., and attempts to combine hitherto isolated experimental data by making use of the results of Kingsbury's experiments based upon an electrical analogy. The possible causes of divergence in the results obtained by different workers are enumerated and their effect on the general agreement explained. There is considerable experimental evidence to support the basic principles of the method of design derived in the preceding paper by Dr. Swift.

The second section analyses current methods of design in the light of these principles, and explains the reasons for departure from the theoretical method in some cases. Particulars relating to journal bearings used in various types of machines are tabulated, and values of the dimensionless criteria used in actual practice are compared with those suggested by theory. Design examples are worked out, and results tabulated, in order to explain the methods which may be employed in order to secure optimum running conditions in various circumstances, and their resultant effect on performance.

A summary is given in the last section of the existing state of knowledge relating to journal bearings, considered from the point of view of the designer. Further data still necessary are enumerated and the avenues of research yet to be explored in order to obtain this knowledge are explained.
The Determination of Mass Flow in the Vapour-Compression Refrigerator
Authors: Smith E. C.
Published: October 2007

The paper describes an experimental determination of the mass flow of refrigerant per minute and refrigerating effect per minute in a vapour-compression refrigerator, when the state of the refrigerant at the exit from the evaporator was varied over a wide range of superheat temperatures and dryness fractions. The usual methods of measuring the flow of liquids in pipes were not suitable for the present work and a special type of flow meter, described in the text, was developed.

The results obtained were not as theory would tend to suggest, but were substantially modified by practical conditions, particularly for dryness fractions between 0·97 and 0·87. The volumetric efficiency changed abruptly over this range from a higher to a lower value. The reduction was attributed to the effect of re-evaporation of. the liquid portion of the refrigerant in the compressor during the suction stroke, as it was found that the higher volumetric efficiency was obtained when the refrigerant was superheated throughout most of the delivery stroke, and the lower volumetric efficiency occurred when the state of the refrigerant on entering the compressor resulted in liquid being present in the cylinder at the end of the delivery stroke. The reduction in the volumetric efficiency resulted in a corresponding reduction in the mass flow, the refrigerating effect, and the heat rejected by the condenser per minute, and in the coefficient of performance for dryness fractions ranging between 0·97 and 0·87.
Training of Apprentices for Craftsmanship
Authors: Fleming A. P. M.
Published: October 2007

The paper discusses the changes which have occurred during recent years in industrial organization and workshop practice in relation to the problem of the recruitment and training of apprentices for craftsmanship. In order to provide a satisfactory basis for the discussion of this important question, the author lays stress on the conditions which obtain in the large firm with which he is associated, without presupposing, however, that the methods which have been adopted therein are necessarily appropriate to firms manufacturing quite different engineering products. Details are given of the organization of the workshop training provided, and, after an expression of opinion as to the limited suitability of National Certificate courses for a large proportion of apprentices, of the part which the works' school plays in providing classroom instruction bearing more directly on the manual processes with which these apprentices are being called upon to deal. Finally attention is given to the question of the promotion to junior staff positions of these apprentices who have equipped themselves with requisite technical knowledge, and to the difficulty in the firm with which the author is associated of ensuring adequate retention in the shops of the highest-grade workers. A summary of the important considerations pertaining to the problem is given in conclusion.
Racing Motor Car Design
Authors: Railton R. A.
Published: October 2007

The development of the racing car to-day is taking place almost entirely in Germany and Italy. It is true that during the last few years British cars have figured prominently in the lists of world speed records, but the cars used for these attempts are not racing cars at all in the true sense of the term.

The most important single factor in the suspension of a racing car is to keep the unsprung weight down to an absolute minimum, and this is one of the chief aims of the designer. Independent suspension at all four wheels has been found to have advantages quite out of proportion to the mere saving in weight. There is now a fairly general agreement that if the centre of gravity of a racing car is too low, the tendency to skid is increased. Racing cars built on the front-wheel drive principle have had a considerable success in America, but they suffer from the drawback of instability at the critical speed when rounding a corner.

Brakes and transmission have both been developed to a high degree of perfection, but resemble in principle those now used on touring cars. Supercharging is general, largely as a result of special circumstances which the author discusses. The use of heat-resisting alloy steels has also become an important factor in the design of the engines.

The author considers also the influence of fuel, tyres, and streamlined shape on the maximum speed attainable on land.
The Mechanics of Flame and Air Jets
Authors: Davis R. F.
Published: October 2007

Consideration of the conditions existing within the turbulent zone formed by a free disperse jet mixing with fluid at rest surrounding it, leads to the conception of an equation for the mean velocity of the jet in an axial direction. Combining the latter equation with that for the upward drift velocity of the gases in a furnace, an expression is obtained for the trajectory of an overfire, or secondary air jet, projected into the furnace. By a similar process the method is extended to the case of a flame jet, taking into account its acceleration due to buoyancy.

The mechanism of combustion is next considered, commencing with an examination of the factors controlling the position of the ignition point in a flame jet, and the derivation of an expression for its location in a powdered-fuel flame. This is followed by the development of a formula for the burning rate of powdered fuel suspended in air, which when combined with that for the mean velocity in a flame jet, enables a relationship to be established between the flame length and the particle size, for the ideal case of a uniform powder. Subsequently, the grading or non-uniform nature of actual powders is taken into account. A method is also described for plotting a flame characteristic, showing the effect of fineness of grinding, turbulence, and burner design on the losses due to unburnt combustible.
Recent Developments in High-Speed Reciprocating Pumps
Authors: Towler F. H. , Towler J. M.
Published: October 2007

The advent of the self-contained hydraulic press, with its many advantages, has necessitated the development of a compact high-speed pump. For most pressing operations a variable-delivery pump is of little advantage, and such pumps, having rotary valves, are only capable of comparatively low pressures. On the other hand a working pressure of 5,000 lb. per sq. in., with its attendant advantage of compactness, is readily obtainable with pumps having positively seating mushroom type valves. Such a pump is described, which the authors have perfected, and which has a volumetric efficiency of over 97 per cent at 1,500 r.p.m. High volumetric efficiency is essential to obviate noise and vibration at such speeds and to reduce pulsations in the flow to a practically imperceptible amount.

To obtain high volumetric efficiency at high speeds the shape and construction of the suction valves are of paramount importance. Some comparative experimental figures are given for the discharge of valves of various shapes.

Oil is used as the hydraulic medium as it prevents corrosion and ensures that all working parts are copiously lubricated. The pump is immersed in the hydraulic medium and all rotating parts are mounted on ball or roller bearings. The conditions of loading, the effect of deflexion on the journal bearings, and the special design of shaft are fully described. The paper concludes with various illustrations of self-contained hydraulic presses to which this type of pump has been applied.
Diesel Traction on Railways
Authors: Ambady G. K.
Published: October 2007

An analysis is made of the various items of locomotive operating costs and the degree to which each is influenced by the type of tractive unit selected, namely, steam or Diesel. The effect of the possibility of a higher “availability” or “serviceability” factor with Diesel locomotives is not likely to be as high as may be supposed. Specification and design details of the various components of a Diesel tractive unit are discussed and in the particular case of a locomotive designed to haul a load of 600 trailing tons at a maximum speed of 60 m.p.h., the main design data and performance curves are worked out with and without supercharging.

The author's general conclusion is that Diesel operating costs compared with steam become more and more favourable as the power output required from the tractive unit decreases, when the advantage of a self-propelled vehicle, such as a railcar, over a train hauled by a locomotive becomes more pronounced.
Heat Loss from Gilled Metal Pipes
Authors: Griffiths Ezer , Awbery J. H.
Published: October 2007

In a previous paper, on “Heat Transfer between Metal Pipes and a Stream of Air”, presented to the Institution in 1933, an account was given of measurements on the transfer of heat between plain pipes and a stream of air. The present paper is an extension of this investigation to gilled pipes. Observations have been made on the heat loss from four gilled pipes of diameters between 1 and 2½ inches, with gills varying in diameter from 2 to 4⅓ inches. Each pipe was studied as a single unit in the wind tunnel, whilst one size of pipe was also examined when built into a battery of similar pipes placed with their axes across the direction of the air flow.

The result found for plain pipes, namely, that H/ κ θ is a function of V d/ v only (where H is the heat loss per unit length from a pipe of diameter d at a temperature excess θ over air of thermal conductivity κ and kinematic viscosity v, moving at velocity V), requires modification in the case of gilled pipes. In the former case, H is the heat loss per unit length, and is thus equivalent to the product of the circumference and the heat loss per unit area. The latter interpretation, when dealing with the results for the gilled pipes, does not give systematic results, if the heat loss per unit area is calculated on the total exposed area of the pipe. Moreover, in defining the surface emitting heat, the quantity d, the pipe diameter, is only unambiguous for plain pipes. In the case of gilled pipes, it is found that the most consistent treatment of the results is obtained if d is taken to be the “effective diameter” of the pipe, i.e. the total exposed area per unit length divided by π

If the interpretations just explained are given to the quantities H and d, then it is found that to a first approximation, the relationship between H/ κ θ and V d/ v is the same for a gilled and a plain pipe. The observations have also been analysed from the point of view of the temperature of the edge of the gill, relative to that of the air and that of the pipe.
Impact Stresses in a Freely Supported Beam
Authors: Arnold R. N.
Published: October 2007

The paper reviews various theories used in estimating impact effects on a freely supported beam, and points out the error which may be introduced if the assumption is made that elastic forms are similar under dynamic and static loading.

An apparatus is described, in which the beam is a railway rail of 8 feet span, subjected to central impacts, strain measurements being made along the flange by means of small scratch-extensometers. An analysis of records from these instruments gives an indication of the instantaneous bending moment distribution occurring at time intervals of 1/1,000 second during impact, and the bending stresses are shown to be approximately 20 per cent greater than those calculated by assuming “statical equivalence”.

The variation of load between weight and beam during impact is recorded by the vertical strain of the rail web under the load, and a complete series of records for various weights and velocities is given. These records demonstrate the occurrence of “sub-impacts”, the weight in certain cases striking the rail five times under what the human eye observes as a single impact. Diagrams of results obtained by calculation from an equation derived by Timoshenko show agreement in form with the load variations recorded by the scratch extensometers. Results obtained by measurement from the area of the ellipse of contact are also given, and loads—obtained by four independent methods—are drawn to a base of impact velocity for various weights. The experimental results are shown in all cases to be at least 2½ times those predicted by the assumption of “statical equivalence”, and (allowing for calibration difficulties) are in fair agreement with those obtained from the Timoshenko equation. Mention is made of the practical significance of the results.
The Development of Single-Bucket Excavators
Authors: Savage W.
Published: October 2007

Since the presentation of the last paper on excavator practice to the Institution by F. H. Livens, M.I.Mech.E., and W. Barnes, M.I.Mech.E., in 1920,† a great many changes have taken place in both the application and design of excavating machinery. The application of this type of machinery has been dealt with on several occasions during the intervening years, and as recently as December 1934, Sir Henry Japp dealt very fully with “Modern Methods and Plant for Excavations” in a comprehensive paper read before the Institution of Civil Engineers.‡ This paper therefore deals more particularly with the progress in design of the excavator itself rather than its application.

Attention may first be drawn to the extension of the range of sizes available in both directions. In 1920 machines carrying dippers of 6 cu. yards capacity and weighing about 250,000 lb. represented the upper limit in size, whilst machines carrying dippers of [Formula: see text] cu. yard capacity were the smallest available. In 1937 machines having dipper capacities of as much as 33 cu. yards and weighing 2,500,000 lb., or as little as [Formula: see text] cu. yard and weighing 15,000 lb., were manufactured.

A greater number of distinct types have also been developed. Twenty years ago types in common use were the shovel and the grab or clamshell. To-day, drag-line, drag-shovel, and skimmer-scoop equipments are largely used, and these have been developed to meet the growth of application of the single-bucket excavator, enabling it to do work for which it was originally unsuited.

In 1920 steam was practically the universal motive power, but this has given way to the internal combustion engine and electricity, and is now virtually obsolete for this purpose.
Aircraft Efficiencies
Authors: Piercy N. A. V.
Published: October 2007

The past seven years have witnessed remarkable developments in aircraft. They have marked the advent, for example, of autogyros, cantilever monoplanes, landing flaps, variable-pitch airscrews, and retracting undercarriages. Equally apparent to engineers will have been the perfection of powerful and compact engines weighing little more than 1 lb. per h.p., the adoption of skin stressing and ducted cooling, the shrinkage of wing area until nearly twice as much load is carried per square foot, and the elimination of exposed struts, wires, levers, and rivet heads. Speeds have advanced greatly with little sacrifice in flying weight per brake horse-power or in useful load. Thus there has occurred a very notable increase in the efficiency of aircraft, exercising a profound influence on aerial transport. Many methods of construction, which have been especially devised to meet stringent conditions as regards economy in weight, should also find application in other high-class engineering productions. Again, the new knowledge of fluid motion and matters associated with it, constituting the engineering science of aerodynamics, must eventually prove of service in hydraulics, heat transfer, ventilation, and kindred subjects.

In the paper some of the main considerations affecting the efficiency of aircraft are described. Exhaustive discussion would form too comprehensive a subject, and it has been decided to consider especially those factors in which fluid motion plays a prominent part. Where possible, however, the treatment takes into account structural and other efficiencies attainable in given circumstances. The point of view adopted is that of civil transport, where efficiency is most urgent. Discussion will turn essentially on speed and, in justification, it may be remarked at once that ( a) speed is exceptionally important in the air since the drift of head winds must be subtracted in full, and ( b) high speed is the prerogative of aircraft, being in the nature of things most economically and safely attained in their case.
Some Problems in the Transmission of Power by Fluid Couplings
Authors: Sinclair Harold
Published: October 2007

The paper deals with some of the problems that arise in the transmission of power by fluid couplings working on the Föttinger principle in connexion with internal combustion engines and electric motors driving a variety of loads. The influence of the core guide ring on the torque and speed characteristics in fluid couplings of the variable-filling type is considered, and an indication is given of the changes in thrust as the filling of the working circuit is varied. Considerable progress has been made towards the simplification of auxiliary means for controlling the quantity in the working circuit. Particulars are given of several methods of dealing with the residual or drag torque in fluid couplings of the constantly filled type, for use with change gear drives. Slip curves relating to backward curved impeller vanes illustrate the variations between theory and practice in this case. Methods of mounting couplings on engine crankshafts and arranging outboard or driven shaft bearings are illustrated, and a variety of applications of fluid couplings are considered from the aspects of heat generation and dissipation.

The internal forces in the ring valve type of fluid coupling may be utilized to close the valve automatically in order to disconnect the drive in case of overload.
Measurement of the Fineness of Powdered Materials
Authors: Heywood Harold
Published: October 2007

The paper describes in detail the methods of analysis at present available for measuring the fineness of powdered materials used in engineering and industrial processes. Definitions of particle size and shape are discussed, and examples are given of the size-distribution curves for typical industrial powders. Sieving or screening is used for the size grading of the comparatively coarse particles, and processes involving motion in a fluid for particles smaller than the limit of sieving. The theory of sieving and the relationship between particle size and sieve aperture are discussed. The equivalent sizes of round, square, and slotted apertures have been measured and results are given.

The motion of irregularly shaped particles in a fluid is briefly described, and a method is given for calculating the falling velocity of such particles when the fluid flow round the particles is turbulent. The procedures used for the fineness analysis of sub-sieve particles are: elutriation by means of air or water, sedimentation, hydrometer readings, and the obscuring of a beam of light by dilute suspensions of the particles. Each of these processes is fully described, and the respective merits and disadvantages discussed. Tables of the nominal apertures of all the standard sieve series in industrial use, and a bibliography of about 150 references are included in the paper.
Observations on the Arc Welding and Gas Cutting of High-Tensile Low-Alloy Structural Steels
Authors: Wilkinson T. B. , O'Neill Hugh
Published: October 2007

High-tensile structural steels generally contain relatively small additions of alloying elements which affect their welding properties because of hardening effects. The paper gives data regarding the composition and test values of some typical high-tensile steels, together with results on metallic-arc welded joints. Laboratory cracking tests to determine the weldability of steel plate are described, and their utility is demonstrated. The composition and inherent grain size of the steel, together with the conditions of welding, affect the properties of the heat-transformed zone. It is desirable to limit the carbon content to 0·20 per cent; and for single-run fillets the use of a relatively slow welding speed of 4–6 inches per minute, with a fillet size of not less than half the thickness of the plate, has given the best results in the authors' work.

The properties of various covered electrodes have been studied. Carburization experiments on all-weld metal reveal interesting differences between electrodes.

The cutting of these steels by gas is considered, in so far as most of the factors influencing weld hardness may operate, to produce cut edges having hard surfaces of reduced ductility.
Transatlantic Air Transport with Particular Reference to Flying Boats
Authors: Gouge A.
Published: October 2007

Until within the last few years the efficiency of the aeroplane was such that Atlantic crossings were made under hazardous conditions with very much overloaded machines carrying no pay load. In 1937 and 1938 a number of survey flights were carried out with considerable success, and there is no doubt that the performance of the modern aeroplane makes the direct route practicable.

The author outlines several designs for aeroplanes and seaplanes for a transatlantic service, and is of opinion that, largely on account of take-off and landing problems, flying boats will be used. Consideration is given to the influence of improvements in materials, high-altitude research, and the compression-ignition engine on the future development of large transatlantic flying boats.
Some Problems in the Design and Operation of Merchant Vessels
Authors: Lee Robert C.
Published: October 2007

This, and the following American papers by Mr. Ripley, Mr. Horner, and Mr. Allen are reprinted by permission of the American Society of Mechanical Engineers. They were to have been discussed in conjunction with the four preceding English papers at the Joint Meeting in New York, which was cancelled owing to the outbreak of war.

This paper presents certain technical aspects of ship design and operation as viewed from the standpoint of the executive administration of the merchant marine. The author evaluates the recent developments in hull and machinery design and construction in terms of economics. From the records of the Scantic Line and the American Republics Line, operating cost figures are cited to demonstrate the relation of the various factors involved in ship operation. A review of shipbuilding costs and sales values of ships is included. Among other important matters discussed in the paper are safety provisions, crew training and personnel relations, and finally mention is made of the need for better and more efficient methods of cargo handling. The problems are proposed, as the author states, without solutions being available for many of them, in the hope that subsequent discussion may develop appropriate answers.
High-Speed Lightweight Trains
Authors: Ripley C. T.
Published: October 2007

The purpose of this paper is to outline the changes which have occurred during the last five years in high-speed passenger train cars and in motive power for hauling them and the economic factors which have brought about these changes. The new designs for passenger cars and the materials used in their construction are discussed. A detailed comparison of steam locomotive and Diesel-electric locomotive characteristics as they affect the operation of these new high-speed trains is presented. Test data are included to indicate the importance of comparative stress in track produced by the two types of power. Reference is made to the steady improvement which has been made in steam locomotive design, but it is shown that there is a need for some rather extensive experimentation to make this type of power more suitable for this particular class of service. In conclusion, the author presents his views on the general results which have been secured from the operation of these new trains and the probable trend in their future development.
The Horizontal Carriage of Granular Material by an Injector-Driven Air Stream
Authors: Wood S. A. , Bailey A.
Published: October 2007

Pneumatic conveyance is coming into increasing use in industry. The investigation described was intended to explore general principles.

Tests were made with an experimental horizontal conveyer, using sand and linseed respectively as the materials conveyed. The air stream was maintained by an injector with an annular high-pressure nozzle surrounding the conveyer pipe. The grains were allowed to fall into the air stream at the inlet, and were collected in separators at the outlet.

The test results showed that there is a definite optimum position for the injector in the pipe line, and that it is an advantage to use a divergent diffuser at the outlet end. Definite relations were also found to exist betweeen ( a) the air velocity and the rate of conveyance of solids, ( b) the pressure gradient in the pipe and the injector pressure, and ( c) the additional pressure drop due to the grain and the rate of grain conveyance. There are indications that the effective coefficient of friction between the grain and the pipe falls as the grain velocity increases; this conclusion is borne out by visual observation, which shows that the path of a grain consists of a series of leaps, whose length increases with the grain speed.
An Investigation into the Permissible Load-Carrying Capacity of Steel Wire Ropes for Hoisting with Special Reference to Deep-Level Winding on the Witwatersrand Goldfields
Authors: Dolan J. J. P. , Jackson W. G.
Published: October 2007

The aim of the paper is to determine the stresses to which a wire rope is subjected during winding operations, to assess its condition during its operating life, and to correlate its life history with the autographic load-extension diagrams, taken under the statutory periodic tests at the Government Mechanical Laboratory.‡ Theoretical analyses of rope stresses due to different causes are examined in the light of records obtained by decelerometers and cinematographic cameras, and data relating to six hundred ropes, each not less than 1¼ inches in diameter, are analysed statistically. Published reports of British, American, and German investigations are compared and utilized, and the relations of the factor of safety to accident statistics and to the characteristics of the rope are examined. The decrease of the factor of safety with the increase in depth is studied, and the paper concludes by advocating the legalization of a lower factor of safety for deep-level winding, and recommends that this can be best effected by the adoption of the capacity factor method, first proposed by Vaughan.
The Examination and Tests of Welded Parts for Steam Power Plant
Authors: Goodger A. H.
Published: October 2007

The object of the paper is to give the results of certain experimental and routine inspection work rather than to lay down rules of inspection and testing. An outline is given of the margin obtained between some of the properties and requirements of actual drums and the specified limits.

European practice appears to favour acetylene welding for the butt welding of tubes. Normally acetylene welds do not suffer from basal cracking, but they do suffer from lack of penetration; the paper gives methods by which this can be avoided, and suggests forms of joints for tubular welds. The inspection of tubular welds presents many problems, but certain non-destructive tests have been successfully applied, and a number of X-ray examinations on site are described. A useful method of inspecting large numbers of tubular welds by sample consists in carrying out a reverse bend test on a tongue sawn out of the tube and pressed round a former.

The paper also contains the results of extensive experience of the heat treatment of welds on site.
An Investigation into the Occurrence and Causes of Locomotive Tyre Failures
Authors: Newberry C. W.
Published: October 2007

A detailed investigation has been made into the causes of locomotive tyre failures from two standpoints: first to determine the cause of any particular failure, and second to find general relationships between effect and cause in the matter of tyre defects. Examples are given of the examination of individual failures, and of experimental work directed to the improvement of wheel and tyre. In a statistical review, it is shown that fatigue is the major cause of tyre failure, and many of the factors which might influence the development of fatigue failure have been critically examined and their responsibility assessed. In conclusion it is noted how, by a change in tyre boring methods to increase the effective fatigue strength of the tyre, and by modifications in design to ensure more uniform stress distribution in the tyre, the occurrence of fatigue failures has steadily declined.
The Design and Manufacture of Bursting Disks
Authors: Lake G. F. , Inglis N. P.
Published: October 2007

Bursting disks are frequently used to prevent the pressure in parts of chemical plant from reaching a dangerous value. In the manufacture and supply of such disks the working conditions must be carefully studied and special attention devoted to metallurgical detail to ensure high reliability in the disks. The types of disks which have been tested and used during the authors' experience, and the factors involved in their design for particular conditions, are discussed. From experimental results the maximum value of the ratio of working pressure to bursting pressure may be chosen in order to limit the creep in service to a reasonable amount. If a bursting disk is designed to operate at a temperature above room temperature, the degree of protection afforded at temperatures below the normal operating temperature may be less, owing to the variation in strength of the disk with temperature. Examples are given of the uses to which bursting disks have been applied.
Vortex Pumps, or, Slip in the Centrifugal Pump
Authors: Price Owen A.
Published: October 2007

The current theory of the centrifugal pump does not correspond with its actual performance; it suggests a reserve of 30–50 per cent of pumping capacity available to the designer. The author questions the existence of this margin and examines the energy of rotating bodies of fluid. All flowing vortices must be “hollow” to permit of a continuous admission of fluid at their centres, and the energy expressions are adapted accordingly. No discrepancy is found between the performance of a selected centrifugal pump and its corresponding hollow vortex.

In order to test this conformity under widely differing conditions, test performances of pumps of different design are examined. The examination reveals limitations to this conformity. By analogy with other forms of slip, a “slip ratio” is defined and employed to relate pump and vortex theory, the pump theory representing the capabilities of the vane and the vortex theory the performance of the pump. Emphasis is placed upon the importance of studying the physical properties of the moving fluid rather than the potentialities of the actuating vane.
The Admiralty Cathode Ray Oscillograph Engine Indicator
Authors: Smith F. D. , Lakey E. H. , Morgan H.
Published: October 2007

The Admiralty cathode ray oscillograph indicator was developed for use on compression-ignition engines of medium- and high-speed types. The size of the engine has not necessitated the development of the smallest possible unit. It consists of a pressure-sensitive device based on the magnetophone principle. The pressure to be recorded deflects a steel diaphragm and changes an air gap in a magnetic circuit. The magnet is energized by a high-frequency (20,000 cycles per sec.) alternating current flowing in an encircling coil. The pressure on the diaphragm modulates the high-frequency current, and the modulations are observed on the screen of a cathode ray oscillograph. The advantages of a high-frequency current in this connexion are: (1) all frequencies below about 2,000 cycles per sec. are faithfully reproduced; (2) steady pressures are recorded and calibration is effected with an ordinary pressure gauge; (3) amplifier and circuits have to transmit only a comparatively narrow band of frequencies. A disadvantage is that the upper limit of frequency (2,000 cycles per sec.) is not sufficiently high for the study of very rapid variations. The precautions necessary to ensure accuracy are discussed, and some examples of typical records obtained with the instrument are reproduced.
Stress Measurement by Magnetostriction
Authors: Smith F. D. , Luxford C. A.
Published: October 2007

If a ferromagnetic material, for example nickel, is mechanically stressed, the magnetic permeability changes; the effect is large. The paper shows how the effect can be used to study transient mechanical stresses. The stress is applied, by suitable mechanism, to the ferromagnetic core of a transformer or coil, and the resulting magnetic changes of the core are observed, by the help of appropriate electrical circuits, on the screen of a cathode ray oscillograph, or otherwise. The conditions to be observed for success are set out, and numerical data are given as a guide to the design of magnetostriction stress-measuring devices.
Plastic Yielding and Fatigue of Ductile Metals. A Criterion and Its Application
Authors: Bailey R. W.
Published: October 2007

Based upon a hypothesis of surface anisotropy of an otherwise isotropic material, a criterion of the yielding of a ductile metal is suggested which embraces the several well known criteria as special cases. This criterion for a system of principal stresses X, Y, Z (= 0) takes the form [Formula: see text] = constant; or [Formula: see text] = constant, which for component shear and direct stresses, q and f respectively, becomes[Formula: see text] = constant, where f/q must fall in the range √2 to 2.

The proposed criterion is considered to be applicable in character to fatigue of a ductile metal, and it is applied to derive, from direct and shear stress fatigue test results, limiting fatigue stresses for any combination of shear stress and direct stress in phase, which is the most severe condition. Analysis indicates that the presence of static shear stress may increase the ability of a steel to withstand reversing direct stress. Apparently an opposite effect occurs when direct stress fatigue test results conform to the Goodman or modified Goodman diagrams.
Exhaust-Pipe Effects in a Single-Cylinder Four-Stroke Engine
Authors: Mucklow G. F.
Published: October 2007

The paper deals with an investigation of the fluctuations of pressure, due to piston motion on the exhaust stroke, which occur in the exhaust pipe of a single-cylinder four-stroke engine. Indicator diagrams of exhaust-port and of cylinder pressure, and measurements of air consumption were recorded, using exhaust pipes of three different diameters at three standard engine speeds; the exhaust pipe length was varied over a wide range in each case. In the light of the data thus obtained, the effects on air consumption of progressive alterations in valve timing were studied under known conditions of exhaust port pressure. Further trials were then carried out in which the valve timing which gave the maximum air consumption was determined for the full range of conditions of speed and exhaust pipe dimensions. The experimental results are discussed, and a method is derived by which the pressures in the exhaust port throughout the cycle may be obtained from theoretical considerations; the method is also directly applicable to induction pipe conditions.