bluuebunny/crossref_metadata_2025 huggingface dataset:
Radium in Engineering Practice
Authors: Pullin V. E.
Published: October 2007

Considerable advances have recently been made in nondestructive testing, and a new transportable X-ray laboratory is illustrated in the paper to show that X-rays have achieved a definite, if limited, function in this field. The paper is mainly devoted to a discussion of the properties of radium as a radiographic agent to show how it compares in value with the older X-ray method. The disintegration theory of radioactive materials is outlined and the relative wavelengths of various components of the so-called electromagnetic spectrum, used roughly to indicate their penetrating power, are given. The method of preparing radon is described as it has the great advantage that its use would afford an approximation to a point source of radiation. When employing one of the radium salts, the radium must be removed an appreciable distance from the sensitized film to obtain good definition, thus increasing the exposure time.

Careful directions are given for the safe handling and storage of the element. The exposure camera in use in the Research Department, Woolwich, is described and curves are given indicating safe working distances for operators. Many experimental refinements making for clear radiography are mentioned. In the case of X-rays the effect of scattered radiation militates seriously against good results, whereas in gamma-ray photography there is practically no such harmful effect. Hence heavy irregular specimens may be radiographed by radium in perhaps one exposure.

Exposure curves for radium, based upon experimental data obtained in the author's laboratory, are given. Owing to the general employment of photographic intensifying screens to shorten exposures, it is not possible to rely on calculations based on the inverse square law.

The uses of X-rays and radium are compared and the particular advantages of radium illustrated by a large number of radiographs. X-rays have overwhelming advantages in the examination of metallic structures up to a thickness of about 3 inches. Radium, on the other hand, may be employed in the investigation of metals up to 8 inches or more in thickness.
The Stresses in Fusion Joints
Authors: Coker E. G. , Levi R. , Russell R.
Published: October 2007

Modern use of fusion joints instead of riveted or bolted connexions has produced a variety of new forms which offer numerous fields of inquiry covering a great range of problems. One set of problems relates to stress distribution directed more especially to the determination of the maximum stresses in fusion joints. This is almost entirely an experimental matter, since nearly all such joints have discontinuities imposed by practical necessities which render them insoluble by theoretical analysis, while little or no help can be gained from our existing knowledge and long experience of riveted and bolted joints on account of their essentially different nature.

The present inquiry deals with problems of plane stress distribution in which models are used for measuring the stress at any point required by photo-elastic means, and in the first instance some typical butt welds of an unsymmetrical type are analysed experimentally.

Other ways of connecting plates in line are then considered in which a joint is made by a lenticular section of weld metal on one side and a cover plate on the other, the ends of the latter being joined to the main plates by triangular sections of fusion metal. When the gap between the two main plates is sufficient the lenticular section of metal may be replaced by a pair of triangular fillets binding the inner ends of the plates to the cover strap, and this form is also dealt with. The effects of triangular fillets of lesser height than the butt straps and of corresponding fillets of curved quadrantal form are also examined with reference to a double butt strap joint. The paper concludes with a brief summary of the main results afforded by the experimental analysis.
Heat Liberation and Transmission in Large Steam-Generating Plants
Authors: Robey E. W. , Harlow W. F.
Published: October 2007

The demand for heavier duties and exacting guarantees of performance which has accompanied recent developments in steam-raising plants, has necessitated closer inquiry into the fundamental principles on which their performance depends. The authors present their views on certain aspects of the subject. These have been formed as a result of experience, combined with a consideration of the work of laboratory investigators. It would appear that important facts revealed by laboratory research do not always receive the attention due to them, and frequently erroneous ideas persist for years without question.

The paper discusses the function of the chain grate mechanical stoker with particular reference to the subject of furnace design and secondary air application. It deals with the effect on the size and cost of equipment generally, which would result from a closer observance of the laws of heat transfer and frictional loss in flowing gases, and discusses particularly the phenomenon of delayed heat release in flue gases and the effect of this in boiler plant performance. The cause and prevention of air heater corrosion is dealt with, and the results of investigations into the dew point temperature of flue gases are given.
The Geared Marine Oil Engine
Authors: Bradbury C. H.
Published: October 2007

Although it is now more than ten years since the first geared oil engine installation put to sea, no country other than Germany has made any serious attempt to exploit this method of propulsion. The success of Germany's geared ships has, however, completely proved the reliability of this type of drive, and has exploded the once prevalent belief that mechanical reduction gearing would not withstand the uneven torque of the oil engine.

The author first gives a brief historical survey of the geared oil engine ships at present in service, beginning with the original vessels of the Havelland class and finishing with Germany's “pocket” battleship Deutschland.

The advantages of incorporating reduction gearing are then dealt with, the author maintaining that the disadvantage of added weight due to the inclusion of gears is more than compensated for by the advantages resulting from smaller engines running at higher speed.

The types of drive in common use, namely, the rigid and the “Vulcan” types, are then described, together with the method of obtaining synchronized starting and reversing.

It is pointed out that, although torsional vibration problems disappear to a large extent with the “Vulcan” drive, they are of extreme importance in the case of rigid drives. A complete analysis of the question is therefore made at the end of the paper, and expressions are obtained from which may be calculated the natural frequencies of the normal types of installation. A worked example is included to show the application of these expressions.
Liverpool and the Atlantic Ferry
Authors: Austin J.
Published: October 2007

Liverpool shipowners have played prominent parts in the long struggles for supremacy on the North Atlantic between the more notable steamship companies, such as the Cunard, White Star, Collins, Inman, Guion, Hamburg-Amerika, and Norddeutscher Lloyd Lines, and associated with their names are those of the celebrated engineers and shipbuilders who were responsible for building the transatlantic mail steamers. An historical account is given of the evolution of the mail service from its commencement in the year 1710 to the present day, and includes the British Government Post Office Packet service commenced in 1710 by the sailing packet brig Royal Anne, the inauguration in 1816 by the Black Ball Company of the first regular sailing packet line, the commencement of the Atlantic Ferry in 1840 by the Cunard Line, and the evolution of the mail steamer to its present size, as represented by the liner No. 534 now building. This period covers the development from wood to iron, and iron to steel, for the construction of hulls, the change from sail to steam, from paddles to single, twin, triple, and quadruple screw propellers, from simple to compound, triple-, and quadruple-expansion reciprocating engines, the development of the Parsons direct and single- and double-reduction geared turbines, the change from tank boilers to low- and high-pressure water-tube boilers, and the evolution of passenger accommodation to its present standard.

A few observations are made on the navigation and propulsion of modern liners. Tables show the record passages of Atlantic liners and dimensions of the present-day big ships. The state-rooms, lounges, ballrooms, cinema theatres, swimming baths, sports decks, and dining saloons in the modern liner are briefly described.

The author thinks it is improbable that the Atlantic steam ferry will be supplanted by an air ferry, and he gives an account of the competition with foreign lines which receive subsidies for shipbuilding and operation, and explains the reasons for building No. 534, and the part which Liverpool and the Atlantic Ferry might play in the future development of the United States of America and the Dominion of Canada.
The Embrittlement of Low-Carbon Steel
Authors: Lea F. C. , Arnold R. N.
Published: October 2007

The paper deals with those changes in the mechanical properties of steel having a low carbon content, which occur as a result of quenching from temperatures up to 900 deg. C. Attention is directed mainly to brittleness, especially to that resulting from ageing at atmospheric temperature, which the authors term “age embrittlement.” The range of temperature in which this occurs appears to include those temperatures used in the carburizing treatment of steel as well as lower temperatures. It is suggested that case-hardened steels should be subjected to a final tempering treatment after quenching to avoid the possibility of core brittleness.

Theories are briefly discussed, but at present no direct explanation of the phenomenon is forthcoming, as X-ray and microscopic examination reveal no abnormalities in the age-embrittled steel. Ageing at 100 deg. C., after quenching, shows distinct age hardening, but this is found to be dissociated from age embrittlement.
High-Pressure Plant for Experimental Hydrogenation Processes
Authors: Barber A. T. , Taylor A. H.
Published: October 2007

The paper gives an account of some of the mechanical difficulties experienced in the development and operation of experimental plant for the hydrogenation of coal and tar for the production of motor spirit. Particulars of the various stages of progress are given, from small autoclaves up to a continuous plant capable of producing up to 300 gallons of spirit per day.

The pressure plant is operated at 3,000 to 6,000 lb. per sq. in., and at temperatures up to 950 deg. F. Hydrogen produces complete disintegration of the structure of mild steel under the higher temperature conditions. The use of special alloy steels reduces the liability to hydrogen attack, giving longer working life and allowing higher working pressures, but satisfactory service can best be obtained by insulating the pressure-resisting walls from the heating medium so as to avoid heating the metal beyond 200 deg. F.

Various methods of making suitable joints for high-pressure pipes and cylinders are described, and the results of microscopic examination of sections of cylinders are given in Appendixes.
Heat Insulation as Applied to Buildings and Structures
Authors: Allcut E. A.
Published: October 2007

The insulating materials and conditions described in the paper are those relating to such temperatures as are likely to be met with in heating, cooling, ventilating, or refrigerating practice. The symbols and nomenclature used are those adopted by the Committee on Heat Transmission of the National Research Council (U.S.A.).

The first section describes respectively, the hot-plate and hot-box methods of testing, the former being the more suitable for materials which are comparatively homogeneous, and the latter for walls or other built-up sections. Illustrations are given of the hot-plate apparatus at the University of Toronto, on which much of the experimental work was performed. It is frequently impossible to compare tabulated values of heat conductivity because of differences in test conditions, and accordingly in the second section the effects of ( a) mean temperature and temperature coefficient, ( b) differences of temperature on the hot and cold sides, ( c) superficial pressure, ( d) surface resistance, and ( e) time effect, are considered in detail and an attempt is made to indicate their relative values. A table of characteristic conductivities is given at the end of the paper. The third section deals in a similar manner with the effects of differences in the materials themselves or in their application. These include the influence of: (1) size and thickness of samples, (2) laminated structure, (3) density of fibrous and cast materials, (4) air spaces in materials or structures, (5) moisture, and (6) infiltration of air or gases.

The objective in all cases is to obtain the greatest insulating value per unit of cost, and this is not always favourable to the use of material having the lowest conductivity. Structural strength and resistance to fire, moisture, and vermin are frequently important factors. The paper concludes with some statistics concerning the production and consumption of insulating materials in Canada.
The Yield of Steel Wire under Stresses of Very Small Duration
Authors: Mason William
Published: October 2007

A steel wire 53 feet long was suspended vertically from a fixed point. Near its lower end a stop was soldered to the wire; a tup, sliding on the wire, was allowed to fall on to the stop from appropriate heights. Waves of tensile stress were thus sent up the wire and reflected at the fixed top. Extensions were measured on certain gauge lengths at the top of the wire. The form of the wave front was inferred from these measurements and from the corresponding distances travelled by the stop; the stresses were calculated from the extensions.

The impacts of the tup on the stop were repeated after heat treatment, at a normalizing temperature, of the middle part of a 4-inch gauge length. The static yield being 16·3 tons per sq. in., a yield was found with a wave rising from 3·4 to 28·7 tons per sq. in. in 1·25 × 10−4second and falling again to 3·4 tons per sq. in. after a further 0·45 × 10−4second. Yields above the static yield but lower than the yield just mentioned were found with waves of less intensity but of longer duration.

A limiting “higher” yield stress for indefinitely small duration of the stress is inferred. This limiting stress for the wire as normalized was about 30 tons per sq. in., the maximum stress in static tension being 24·8 tons per sq. in. The results are discussed with reference to the “higher” and “lower” yield stresses.
General Discussion on Lubrication and Lubricants: Group I. Journal and Thrust Bearings
Authors: Swift H. W.
Published: October 2007

Journal and thrust bearings are conveniently grouped together for the purpose of this discussion because they are at present the only types of bearing which can reasonably claim to take advantage of pressure film lubrication. The advantages of film lubrication are very real, since the frictional losses are a mere fraction of those under any other regime, and continuous running of bearings at high rubbing speeds would be quite impossible without the intervention of a fluid film.
Machine Tool Tests and Alignments
Authors: Schlesinger Georg
Published: October 2007

Limits and tolerances are the basis of all machine manufacture. Fourteen European countries adopted the system known as the ISA (International Federation of National Standards Associations) in December 1936; the system covers all grades of finish from the finest roller bearings to rough agricultural machines. Certain fixed principles of measurement must be observed, both in the manufacture of new machines and in the repair of old ones; for instance, extremely fine boring and grinding machines and jig borers are now obtainable and can be used equally for the manufacture of a new motor car or for the overhauling of an old one.

Before a satisfactory basis for the establishment of correct limits for the manufacture of, say, drilling machines, lathes, and milling machines, the deformations set up during the cutting operations must be known. These deformations must therefore be measured during actual cutting. The measuring apparatus as applied to lathes, drilling machines, and milling machines, though varying greatly in individual cases, can be adapted to this research, which furnishes information on the admissible variations in deformation—which is of use during inspection—and on the forces and bending and twisting moments—which is of use to the designer. These records furnish manufacturers with the information required for organizing the sequence of operations when building machines to work with any desired precision. The “balance sheets” of various machines, giving the relationships of the forces, speeds, feeds, section of chip, power required, and efficiency, are of great value both to manufacturer and user.
The Combustion Process in the Compression-Ignition Engine
Authors: Drinkwater J. W. , Egerton A. C.
Published: October 2007

The object of the work, which was carried out in the University Engineering Laboratory, Oxford, was to investigate the combustion process in a compression-ignition engine by determining the extent of the chemical reactions of the fuel and air at various stages during the compression and expansion strokes. The results of the tests are illustrated by several curves showing the percentage volumes of the constituent gases in the engine cylinder at different points in the cycle.

Various inferences are drawn concerning the combustion in this type of engine. Attempts were made to determine the concentration of aldehydes in the gases, but the tests showed that the amount was less than anticipated. Oxides of nitrogen were detected, and considered to have an influence upon cylinder wall corrosion.

It is suggested that there is scope for further work using the sampling method for investigating combustion problems in engines under running conditions.
The Measurement of the Thickness of Metal Walls from One Surface Only, by an Electrical Method
Authors: Thornton B. M. , Thornton W. M.
Published: October 2007

There is a definite need in the engineering industry for an instrument which will determine accurately the thickness of a metal wall from one side only, and which is portable, robust, independent of external power supply, and easy to operate. The instrument described in the paper fulfils all these conditions. The method is essentially that of comparing the resistance of a metal wall under test with that of a similarly shaped wall of the same material, of which the thickness is known. Current, usually under 10 amp., is supplied by a 6- or 12-volt battery to two current contacts held against the wall and usually spaced 2 or 3 inches apart. The current in the circuit is adjusted by varying the rheostat or the number of cells of the small car-battery employed, until the very small potential drop indicated by the deflexion of a galvanometer connected to two potential contacts reaches a predetermined fixed value. From a calibration curve the thickness of the wall corresponding to the current registered by the ammeter is determined.

The contacts are made on the plates whose thickness is to be measured by means of Evershed and Vignoles spring-controlled rotating points that were originally designed for a four-point method of working. The flexible leads from these, sometimes 100 but usually 30 feet long, are rubber-covered, and are connected to the circuit in the box by plugs and sockets. These are removed for transport and carried in a separate box.

The instrument was originally designed for measuring the thickness of boiler tubes, and examples are given showing that its accuracy in this respect is within a few thousandths of an inch. It was found in practice that the instrument could be used to measure the thickness of mild steel plates up to 1·25 inches and of iron castings, up to 3 inches, with the same order of accuracy. It is also used for the measurement of engine cylinder walls to detect core shift. Examples of these are given in the paper. One notable case was that of the examination of a bank of superheater tubes in a boiler that had given much trouble due to the use of an unsuitable chain-grate stoker. Thinned tubes were at once detected and on being cut out the thicknesses indicated by the instrument were confirmed. Examples are given of the regular use of the instrument in determining the thickness of boiler and superheater tubes, ships' hull plates, tank wagons, and various iron castings that were accessible from one side only.
Roller Crushers
Authors: Miller W. T. W. , Badger G.
Published: October 2007

The paper describes roller crushers used for the reduction of ore, stone, coal, or chemical preparations of similar densities. Single-roll breakers developed originally for the crushing of coal, have been applied for the reduction of semi-hard slippery materials such as phosphate, gypsum, shale, and certain limestones. Two-roller crushers are the most numerous class and their growth from the early Cornish type to the modern high-speed rolls of great size and capacity is illustrated. Three-roller mills have not proved very successful in this particular field of service. Two examples are described and their defects explained. Four-roller machines have proved useful for the crushing of coal and some of the chemical products. Six-roller crushers are not very common. Two examples are shown and reasons are given for their restricted application. Two special types of roller crushers are also discussed, namely Taylor's three-stage coal breaker and the “Simplex” machine comprising two rollers and an intervening rotary disk.

The factors which influence the performance of the rolls are examined in detail and a formula for obtaining their capacity is given. The correlation of the angle of nip and the feed size, and their effect on the diameter of smooth rolls, is emphasized. A time factor diagram is given to show the reason why rolls of large diameter can be run with advantage at the higher circumferential speeds. Figures covering normal power consumption are specified.
Cylinder Bore Wear
Authors: Taub Alex
Published: October 2007

The author has been responsible for the design of engines for a motor car in which the life of the cylinder bore over a period of ten years and a total of eight million engines is 12,000 miles per 0·001 inch wear.

The factors contributing to this result are as follows: (1) thermostatically controlled cooling for water at a minimum temperature of 145 deg. F., preferably 160 deg. F.; (2) crankcase ventilation to eliminate the effects of blow-by in the oil sump; (3) adequate oil supply to cylinder bores; (4) complete control of the lubricant at the piston rings, not at the source of supply of the oil; (5) control of gas blow-by at the rings; (6) leanest possible mixture ratios for general operating conditions; (7) close attention to the type of fuel used to ensure that it is properly vaporized; (8) a uniform hot metal temperature; and (9) an accurate spark advance mechanism.

All these factors are discussed by the author in detail, special attention being paid to the testing of piston rings in the laboratory, the correct use of thermostats, and crankcase scavenging.
An Investigation of the Fretting Corrosion of Closely Fitting Surfaces
Authors: Tomlinson G. A. , Thorpe P. L. , Gough H. J.
Published: October 2007

The paper describes an experimental investigation of the mutual corrosion of metal surfaces in closely fitting contact when subject to vibration. It is shown that the corrosion is mechanical rather than chemical in character. Vibration or alternating surface stress alone will cause no corrosion and it is established that some surface slip, alternating in direction, is the necessary condition. Slip effectively causes corrosion even if reduced to the order of molecular dimensions, and this has been found to occur without exception, whatever the condition of the surfaces. Lubricants modify but do not prevent corrosion. Softer materials in general tend to seize and harder materials to produce corrosion debris. The amount of corrosion does not appear to depend on the intensity of normal pressure, but only on the occurrence of contact. Comparative tests of many pairs of materials show differences in the resistance offered to corrosion, but no pair of materials has been found to be free from the effect. A theoretical discussion of the mechanism of the phenomenon is given in which the idea of ordinary mechanical abrasion is rejected, and a process of molecular attrition, possibly closely associated with fatigue effect, is suggested.
Some Principles of Modern Methods of Water Treatment for Steam Raising
Authors: Hamer P.
Published: October 2007

The paper describes some recent advances in knowledge of the physico-chemical principles on which the correct treatment of boiler feed water is based. Straub's work in America was confined mainly to the tannins, the use of which in boiler compounds is almost traditional. The effect of tannins in the boiler appears to be threefold: (1) the delay of the precipitation of calcium compounds by the action of heat or alkalies; (2) the reduction of the amount of deposit which may be due to a change in the crystal shape of calcium sulphate and calcium carbonate brought about by the presence of tannins; and (3) a marked effect in conjunction with alkali, in preventing corrosion by the formation of protective films.

The principles laid down by R. E. Hall for the prevention of calcium sulphate scaling are restated. Recent work has led to a modification of the theory underlying Hall's recommendations, the significance of which is explained. A short description is given of Partridge's experiments on the growth of crystalline deposits on hot metal surfaces, but further work is necessary to explain why these deposits adhere to the metal. Recently published studies on the solubility of the calcium phosphate precipitated in the boiler, and the effects of sodium salts are described. Mention is also made of the formation of silicate scales and the use of sodium phosphate and caustic soda as preventatives.

It is suggested that the work described in this paper emphasizes the fact that the prevention of scale in boilers is essentially a chemical problem, and that the success of the recommended methods of prevention depends on careful control at each stage of the feed water treatment.
Estimation of the Leakage through a Labyrinth Gland
Authors: Hodkinson B.
Published: October 2007

The usual theory gives leakage per unit clearance area [Formula: see text] but this assumes that the successive pressure drops are all small, and further, ignores the fact that with decreasing back pressure the quantity flowing cannot go on increasing indefinitely, but reaches a maximum, and thenceforth any further decrease of back pressure pn has no effect. Its critical ratio to the initial pressure p0 is given in a diagram which also serves to give the progressive pressures along the gland.

For calculating the leakage quantity a method is given, more accurate than the usual formula above. For the case where the kinetic energy of the fluid is not completely destroyed at each stage, the consequent increase of leakage can be assessed by a correction factor given by a formula made to agree with some test results, but based on the fundamental idea that the stream spreads out conically from the cylindrical surface at a small angle.
The Energy Balance Sheet of the Internal Combustion Engine
Authors: Lanchester F. W.
Published: October 2007

The author has amplified and in some degree revised the treatment described in a series of articles published last year. He believes that the method is new. By presenting the energy balance sheet in the form of a triple account the quantities which cannot be directly determined appear as differences.

For the original articles the author had to fall back on tests of an Otto cycle engine of his own design, dated 1895, but his attention has since been called to an admirable Ph.D. thesis by J. S. Clarke of Birmingham University, the data in which he has been able to use for this paper. It is unfortunate that the indicating of high-speed engines is not yet sufficiently precise to allow of the application of the author's treatment. The production of an indicator capable of giving reliable diagrams up to 2,000 or 3,000 r.p.m. is a matter of great importance.
Recent Developments in High-Speed Oil Engines
Authors: Davies S. J.
Published: October 2007

The developments since the author's paper to the Institution in 1932 are reviewed under the subdivisions: combustion chamber design; injection systems; fuels. While few novel features can be reported under combustion chamber design, the growth of knowledge concerning injection systems and the properties of fuels has been considerable. The processes in fuel-injection systems are now well understood, while the conditions governing the break-up of fuel sprays are now also reasonably clear. The fundamentals of combustion and what determines ignition lag still remain obscure; the interaction of break-up of spray and course of combustion are also indefinite, and trial-and-error methods must still be employed. On the other hand, the cetane scale for assessing the suitability of fuels has been introduced. Reference is made to electrical indicators and the determination of impact loading on running gear during combustion. Two-stroke working and supercharging are discussed.
Motor Transport
Authors: Ottaway E. C.
Published: October 2007

The presentation of a paper to engineering societies of two countries, on a subject of such breadth, involves some difficulties of arrangement. It has been thought best to treat the subject in two parts, with the intention that the first shall deal with the influences which encourage or restrict the engineer in his quest for improvement, and thus serve as a background against which the development of the road vehicle, described in the second part, may be better understood. It may seem incongruous to devote so large a proportion of the paper to the social and economic side of the subject, but in truth no such apology is needed. The engineer must be fully appreciative of these aspects if he is to succeed in the quest for improvements in performance and economy. In the second part it has been impossible to deal with the detail design and performance of every part and type. The more fundamental problems and newer developments have, therefore, been selected for review.
Basic Principles in the Design of Cathode Ray Oscillograph Engine Indicators
Authors: Smith F. D.
Published: October 2007

Increases in the speed and rating of internal combustion engines have necessitated the replacement of conventional engine indicators by the recently evolved cathode ray oscillograph engine indicator. The devices for converting mechanical pressure into an electrical effect fall into three classes according to whether (1) an electrostatic, (2) a resistance, or (3) an electromagnetic effect is used. Only the first and last classes have been found practicable, the first for rapidly varying and transient effects, and the last for slower phenomena. The members of each class can be used with one of three types of electrical energizing circuits: (1) self-excitation, (2) direct-current excitation, or (3) alternating-current excitation. Success in dealing with a particular problem depends upon the choice of a suitable combination of the device sensitive to pressure, and the electrical energizing circuit. The three most useful combinations are the piezo-electric crystal, and the moving iron, or magnetophone, with either direct-current, or high-frequency alternating-current excitation. Magnetostriction and the condenser microphone, both with either direct- or alternating-current excitation, will prove useful when developed further. The essential features of design for the study of the most difficult problems are now understood. The present form of these engine indicators is useful, but there is need for greater accuracy and reliability.
The Elements of Pendulum Dampers
Authors: Zdanowich R. W. , Wilson T. S.
Published: October 2007

The dynamics of a pendulum damper is treated in a more general way than hitherto, all known types being included. A new method of considering the effects of a pendulum damper when fixed at any point in an engine system is developed, showing that its action results in an alteration or displacement of the critical speeds at which the harmonic orders occur.

A convenient method is outlined for arriving theoretically at the best design for a pendulum damper, whatever may be its location in the engine system. As a practical illustration, a brief account is given of experimental work which was undertaken to test the behaviour of a well-known engine when a certain pendulum damper was fitted to the flywheel. A further account of a similar application to a six-cylinder engine is also given. Special forms of pendulums, and a note on the estimation of angular amplitudes, are discussed in Appendix I, and a bibliography and a short list of the most important patent specifications relating to pendulum dampers are also included.
The Static and Fatigue Torsion Strengths of Various Steels with Circular, Square, and Rectangular Sections
Authors: Holley E. G.
Published: October 2007

The paper records the results of a research into the comparative elastic and fatigue torsion strengths of bars of circular, square, and rectangular cross-sections.

The static torsion tests reveal that in the case of square and rectangular sections the use of enlarged ends leads to discrepancies between the experimental and theoretical values of the elastic torsion strengths.

The fatigue torsion tests disclose astonishing fatigue weaknesses in square and rectangular bars, the weaknesses being masked when the ends of the specimens are enlarged.

The fatigue torsion strengths of square and rectangular bars are compared with the fatigue torsion strengths of circular shafts with keyways and it is emphasized that outstanding fatigue weakness may be associated with certain forms of stress distributions even when high stress concentrations are absent.

Consideration is given to the value of the static properties of metals as safe criteria of fatigue strengths.

In an appendix the problem of the raising of the elastic stress in a material when the distribution of stress is uneven is discussed.
The Problems of the Singing Propeller
Authors: Kerr W. , Shannon J. F. , Arnold R. N.
Published: October 2007

The unusual noise emanating from what is known as a “singing” propeller is the direct result of the vibration of the blades. These are disturbed by the irregular hydrodynamic actions of cavitation and vortex shedding and induced by the extreme variations in the wake. It is demonstrated experimentally that a blade with a sweeping plan form and sharp edge, suppresses cavitation and vortex action within the working range of the propellers. Sharpening the blade edges round the periphery, in a wedge-shaped manner, has been applied successfully as a cure to many singing propellers. In addition to suppressing the disturbing forces, experiments show that the sharp edge provides considerable increase in hydrodynamic damping.

The response of the blade to tip and edge excitation is considered. Blade flutter is examined, but it is concluded that such a condition is unlikely. Notes emitted by singing propellers suggest that many modes of flexural, torsional, and lateral vibration are present. It is shown that the lateral types respond easily and their importance is indicated by a number of noisy propellers which have exhibited fatigue cracks conforming to the lateral modes of vibration. It is recommended that the process of sharpening the blade edges be adopted, as this suppresses the exciting forces and damps the response of the blade.
Investigation of Steam Turbine Nozzle and Blading Efficiency
Authors: Dollin F.
Published: October 2007

The paper describes the essential characteristics of the passages forming the fixed and moving elements of multistage high-efficiency turbines, whether impulse or reaction. The problems of nozzle investigations by static and dynamic methods are discussed, and a new nozzle tester is described. Reference is made to the Reynolds number; its physical significance is explained, and experimental results are used to demonstrate its effectiveness as a correlative factor.

The significance of the static (nozzle) efficiency and the dynamic (turbine) efficiency is discussed, and the essentially different way in which they are affected by the discharge angle is pointed out.

A mathematical expression is derived for the relation between static and dynamic efficiency for 50 per cent reaction blading as a function of the discharge angle. This, in conjunction with the Reynolds number, is used to demonstrate the unity and consistency of static and dynamic test results which at first sight seem to be conflicting or unrelated.
The Stresses in, and the Deflexion of, Circular Flat Plates, with a Central Hole, under Normal Forces
Authors: Labrow S.
Published: October 2007

Solutions are given, and presented in graphical form, for the stresses in, and the deflexion of, a thin circular plate when loaded by normal (transverse) forces only, with various prescribed conditions of supporting or fixing the edges.

The method used in deriving these results is an application of a general method for obtaining the direct and, or alternatively, the bending stresses in a thin circular plate under any type of loading. Because of the ease with which it can be applied to problems in which the loading on the plate is quite complex, this general method, due to Professor William Kerr, Ph.D., M.I.Mech.E., deserves to be more widely known, and a brief account of it is given by the author as an introduction to the special problem with which the paper is primarily concerned.
The Relationship between Stress and Strain in the Tensile Impact Test
Authors: Brown A. F. C. , Vincent N. D. G.
Published: October 2007

Apparatus has been devised for the measurement of the relationship between stress and strain on metallic specimens broken in tensile impact. The stress was measured piezo-electrically and the strain photo-electrically.

Five ferrous materials have been examined at rates of extensional strain ranging up to 800 inches per inch per second, with the following results.

With wrought iron there was an increase in tensile strength and considerable increase in yield point as the rate of strain was raised. With medium-carbon steel there was some increase in the yield point. With low-carbon manganese steel, nickel-chromium steel and “Vibrac” steel there was little difference between the impact and static stress-strain diagrams. The energy absorbed in fracture of the specimens in the impact tests was only slightly greater than that absorbed in the static tests.
Wave Action in Gun Run-up Springs
Authors: Taylor H. G. Woodhouse
Published: October 2007

A number of articles and pamphlets have appeared on the waves and oscillations that occur in springs used for commercial purposes, notably the valve springs for internal combustion engines, and it has been shown that the forces experienced, and other results obtained, are very different from what would have been expected from calculations which assumed that the load is applied slowly through the amount of compression available. No such publications, so far as is known to the author, have appeared regarding springs for military use, such as those employed to run the gun up after firing. Textbooks have tacitly assumed that the load is so slowly applied that static considerations meet the case, so they have given the corresponding theory.

That a wave action does occur is observable by eye in some instances. In the 18-pounder Mark II field carriage, so well known during the war of 1914–18, the run-up springs were telescopically arranged so that the inner spring case was carried as a float between the outer and inner springs. That there was a wave action could readily be seen by carefully watching this inner spring case during the recoil of the gun on firing.

There also have been several instances in which a column of identical springs have been employed, and it has been found in use that the spring in one particular position is liable to take a permanent set or to fracture. This indicates that there is a wave action and that it is accentuated at the point concerned. It was a result of this sort that led the author to work out the theory of recuperator springs, taking the time factor into consideration. Their behaviour is shown to be quite different from that calculated on static considerations.
Fans—Their Types, Characteristics, and Application
Authors: Ferguson C. G.
Published: October 2007

A fan is defined by the British Standards Institution as “a machine which propels air continuously, the total fan head never exceeding 1 lb. per sq. in.” When the pressure is above this limit the field of blowers is entered. The paper deals descriptively with modern fans and their applications under the following three main types: ( a) propeller fans, ( b) centrifugal fans, ( c) axial flow fans. The differences in their characteristics and construction appear to justify the classification of ( a) and ( c) as different types.

After recapitulation of the fundamental formulae used in assessing the output, power requirements, and efficiencies of centrifugal fans, the author discusses various test results on actual installations, with some of which he was personally concerned. Axial-flow fans are considered both from manufacturing and from aerodynamical viewpoints, and test results are given, together with curves showing the power absorbed and the efficiency achieved.

In the latter part of the paper the author deals with various applications of fans: to the ventilation of buildings, ships, and mines; as a method of supplying draught to boiler installations by mechanical means; and in the operation of dust extraction plant. The control of fan speed and output by hydraulic couplings is compared with methods of adjusting the inlet vanes, in order to achieve the same result.
Tests on Transport Producer-Gas Units
Authors: Heywood Harold
Published: October 2007

The experimental plant installed by the British Coal Utilisation Research Association for testing gas-producers, filters, and engines is described in detail.

The results of tests on the engine bench show that a petrol engine converted to use producer gas will only develop about one-half of the normal brake horse-power; moreover, the peak power with gas occurs at a lower speed than with petrol, due to the decrease in volumetric efficiency at high speeds. The effect of increasing the compression ratio was not investigated by the author, but tests by other workers have shown that the gain in power obtained by this means is proportional to the increase in the air standard efficiency.

Producer gas-driven engines are very sensitive to mixture strength, and maximum power is obtained with mixtures of gas and air in the proportions theoretically required for the combustion of the gas. Maximum efficiency is obtained with a mixture containing 10 per cent of excess air. Engine tests have also been made to investigate the effect of gas calorific value, of the pressure drop through the producer system, and of petrol addition. Special tests were made to determine the flexibility characteristics of the engine and producer, and the effect of running with various throttle openings, as in actual road operation. Fuel consumption under the latter conditions is about 35 per cent greater than that determined under full-throttle and constant-speed conditions.
The Design Office Problem in the Estimation of the Torsional Resonance Characteristics of Small Marine Diesel-Propulsion Units
Authors: Mitchell R. W. Stuart
Published: October 2007

The problem of the accurate estimation of resonant amplitudes of torsional vibration in small marine Diesel-engined propulsion sets is considered from the viewpoint of the design engineer. A short discussion on torsiographs is followed by the basic theory of the energy method of calculation, with particular reference to the calculation of vibration amplitudes assuming linear damping proportional to the phase velocity of the vibration. Harmonic input torque diagrams are given for a small marine two-stroke engine.

The methods put forward by different investigators are considered by comparing the calculated results with those obtained by torsiograph from a number of marine Diesel units investigated by the author. Both the one- and the two-noded forms are considered. In the former, propeller damping is shown to be the main influence and a method of computation put forward by Dorey is shown to be satisfactory after slight modification. For the two-noded form the position is not so satisfactory. Hysteresis damping in the crankshaft, viscous damping at the bearings, overall velocity damping, etc., are considered in turn and rejected as unsatisfactory. The importance of apparent damping effects—particularly cyclic fluctuations of speed or cyclic irregularity—is stressed, and a method is evolved in which this consideration is utilized in conjunction with results published by Major Carter which the author has found fairly satisfactory to date. It is concluded that much has still to be learnt on the subject before empirical methods can be dispensed with.
The Position and Development of the Gas Engine
Authors: Jones J.
Published: October 2007

The gas engine as developed during the early years of the present century reached its zenith about the year 1914; after the post-war boom of 1918–20 production gradually declined, in the face of its rivals, the compression-ignition engine, and the national grid. In steel works, however, gas engines running on blast furnace gas continued to be a useful source of power and some of these installations reached very large sizes.

The paper, after an historical introduction, provides some useful comparative data of the performance of gas engines and other prime movers, and traces the development of the dual fuel engine (in which oil fuel adds to the power developed by the gas fuel) and refers in particular to some valuable experiments carried out in the works of the Birmingham Tame and Rea Drainage Board. Eventually a type of engine was arrived at in which, by suitable atomizer design, and by modifying the cylinder head and governing gear, the proportion of oil fuel to gas fuel could be varied over a wide range whilst the engine was running on load. The dual fuel engine should go far to reinstate the gas engine as a natural type of prime mover in this country, where rich coal resources exist. In the U.S.A., some important work has been done by the Nordberg Company on a large 3,000 h.p. unit at Coolidge, Arizona, where the engine uses a very rich natural gas for six months in the year, and oil fuel for the remainder of the time.

Finally the author outlines possible directions of development for the dual fuel engine, and suggests two main types employing high-pressure and low-pressure injection respectively. He also points out that in the future, some improvement in gas producers will be necessary, and makes a plea for further development of the bituminous gas producer, in order that its present disadvantages may be overcome.