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Stating that the trend of tractor development must be toward the small tractor that is capable of handling all of the power work on a farm, the author quotes farm and crop-acreage statistics and outlines diversified farming requirements, inclusive of row-crop cultivation. Tractor requirements are stated to be for a sturdy compact design to meet the demands of the diversified farm, which include plowing, seeding, cultivating, hauling and belt-power usage, and these requirements are commented upon in general terms. Consideration is given to farm implements in connection with tractor operation, and the placing of cultivating implements ahead of the tractor is advocated.

The authors enumerate some of the questions that are involved and, after outlining a previous paper on the subject of plows, analyze these questions in part by the aid of diagrams and applied mathematics. Comparative draft data are presented in tabular form and commented upon, as well as comparative hitch-length data. Tractor reactions are explained and discussed in some detail in a similar manner, special attention being given to the reactions on a slope and up-hill. The reactions on cross-furrow slopes are considered, comparisons being made between two tractors that were reported upon in the University of Nebraska tests. The factors involving tractor stability and resistance against overturn are analyzed. The authors state that the analysis presents a definite method of attack for the more correct solution of the proper hitching-point, as well as being a study relating to lug design.

After generalizing on the need for greater consideration in automobile design for service and maintenance requirements, the author discusses the accessibility of car parts at some length with the idea of pointing out difficulties encountered by service-station mechanics when parts are inaccessible, this having a bearing also on the length of time required for repair work and the consequent increased cost to the car owner. Specific instances are given and illustrated in which improvements in design could be made to obviate trouble. These are inclusive of cylinders, cylinder blocks, pistons, bolts, cap-screws, nuts, valves, dashboard instruments and general take-up adjustment. Special emphasis is placed upon certain inaccessible parts that necessitate excessive dismantling.

The author describes the research work on the internal-combustion engine done recently in his laboratory in England, and presents his deductions therefrom, based upon an analysis of the evidence he has obtained to date. Fuels are discussed at length under three specific headings, many tabular data being included and commented upon, and the calculation of thermal efficiency described. Mean volatility and detonation are discussed and the author's present views regarding turbulence are stated, this being followed by a brief summary of the conclusions reached by Mr. Tizard, a colleague of the author, following recent investigations. The influence of the nature of the fuel upon detonation is presented, a lengthy discussion of the subject of stratification being given under three specific divisions, inclusive of comment upon the benefits derived from using weak fuel-mixtures.

The paper is an exposition of the theoretical analysis made by the author of the experimental work of Woodbury, Canby and Lewis, on the Nature of Flame Movement in a Closed Cylinder, the results of which were published in THE TRANSACTIONS for the first half of 1921. No experimental evidence is presented by the author that has not been derived previously by other investigators. The relation of pressure to flame travel is derived first, the relation of mass burned is considered and a displacement diagram constructed, described and analyzed. The break of the flame-front curve, called the “point of arrest,” enters prominently into the discussion and computations; the pressure in the flame-front is studied; the reaction-velocities are calculated; and general comments are made.

That all of the variable factors of automobile friction-losses such as the quantity and viscosity of lubricants, the efficiency of worm-gearing and part-load Modifications are not appreciated, is indicated by an examination of the literature on this subject which reveals a lack of necessary data. Experiments to determine the mechanical losses, including all friction losses between the working gases in the engine and the driving-wheels of the vehicle, are described and supplementary data are included from Professor Lockwood's experiments at Yale. Three distinct possibilities for increasing the fuel economy of a motor vehicle are specified and enlarged upon, gearset experiments to secure and develop data for a four-speed gearset being then described and commented upon at length; photographs and charts illustrative of the equipment used and the resultant data are included.

The author outlines the history of the Air-Mail Service and states that the recent policy has been to carry out the intent of the Congress, to align the service with the desire of the administration for economy and to discontinue too rapid expansion. After a description of the routes and divisions and a listing of the present landing-fields and radio stations, the present equipment is outlined and commented upon, tabular and statistical data being presented. The discussion covers the organization and performance of the service, the casualties, the cost of operation and the policy governing future plans.

Appreciating the fundamental relation of the compression-ratio to the thermal efficiency, the National Advisory Committee for Aeronautics sponsored a comprehensive investigation of this subject at the Bureau of Standards. Every effort was made to measure the engine performance so completely as to make possible an analysis that would not only explain the results of this particular series of tests but form a sound basis for predicting the effect of changes in the compression-ratio on the thermal efficiency of any engine. The experimental work is as yet incomplete and only some of the more salient results are presented in this paper. An eight-cylinder airplane engine was used, having pistons allowing compression-ratios of 5.3, 6.3, 7.3 and 8.3. The differences in compression-ratio were effected by crowning the piston-heads by different amounts.

The author states preliminarily that it is believed that never before in the history of the Society of Automotive Engineers has a single problem been so universally studied as the fuel problem that is confronting the industry today. It is also believed that never before has the industry had a problem which includes such a wide scope of work. The solution calls for the service of every class of engineer, inventor and scientist. The paper does not attempt to give highly scientific information; its real purpose is to appeal for a broader viewpoint and to give illustrations and tests which show that the solution of a problem may lie in an entirely different method than that which often becomes stereotyped by sheer usage, rather than by its specific merit. In the solution of the fuel problem we undoubtedly will have to change some of our old habits, replacing them by studiously worked out viewpoints.

In recent years automobile engines for racing purposes have been very generally rated in accordance with their piston displacement. The natural result has been to encourage the highest possible engine speeds to attain the greatest possible piston displacement per minute. Features of engine design that have been developed under this rule include enormous valve areas, usually obtained by a multiplicity of valves, huge inlet pipes and carbureters, extreme valve-timing and very light reciprocating parts, all of which are undesirable in commercial engines. To encourage the design of engines of a type developing higher efficiency at lower engine speeds, the suggestion is made that a rule be formulated under which cars will be rated in accordance with the piston displacement per mile actually used by them. Such a rule would involve rear-wheel diameter and gear-ratio, as well as the piston displacement of the engine.

The author states that considerable thought has been devoted recently to the relation of fuel end-point to fuel economy. It has been shown that, provided an intimate mixture of fuel-vapor and air is secured, such a mixture will not condense at the ordinary temperatures of the intake. However, on the contrary, crankcase dilution, an excess of deposited carbon, low mileage per gallon of fuel and ignition trouble are being experienced. There appears to be a discrepancy between the efficiency that should be attained and what is actually attained. To investigate this the Bureau of Standards undertook a brief series of experiments to rough out a line of procedure. Regarding compression of a dry mixture, curves are shown to illustrate that gasoline vapor compresses when “dry.” Detonation was evident when using one spark-plug and there was no detonation when using two spark-plugs.

The field of body engineering is broader than it is ordinarily considered to be; the author's intention is to bring to the attention of the automotive industry the breadth and scope of body engineering and outline the way this side of the industry can be considered and developed. After describing the body engineer's position, the author then discusses at some length the conflict between art and economy in this connection. He classifies a body-engineering department under the six main divisions of body construction, open and closed; sheet metal, body metal, fenders, hood, radiators and the like; trimming; top building; general hardware; painting and enameling, and comments upon each. Following this he elaborates the reasons for need of attention to details in body designing and mentions the opportunity there is at present for bringing the materials used in body construction to definite standards.

The purpose of piston rings in an internal-combustion engine is to reduce to a minimum the leakage of gas from and the seepage of oil into the combustion-chamber. Asserting that the widely held idea that the leakage of gas past the piston can be eliminated by the use of good piston-rings is incorrect, the author states three possible paths for such gas-leakage and, after commenting upon them, discusses diagonal and lap joints and the subject of leakage with special reference to them. After considering the design of rings for gas-tightness, the author shows a fortunate mathematical relationship, in connection with the application of uniform radial pressures, regarding the bending-moment stresses. Oil leakage is treated in a similar manner and the conclusion is reached that the properties of the material used are of extreme importance.

The aim of this paper is to stimulate thought on how to accomplish the greatest possible economy in transportation over highways. The fundamental thought is that the expense of highway transportation involves a large number of items that can be grouped into those directly concerned with motor-truck operation and those involving the highway, and that highways and motor vehicles should be adapted mutually so that the greatest economy of transportation will result. Urging that the automotive and the road engineer cooperate in gathering information that will give them a more definite basis upon which to design the truck and the road, the present rapid destruction of roads is discussed and remedial measures suggested. The designing of motor trucks to conserve the roads is treated at some length and a plea for cooperation between the Society and the highway officials is made.

Stating that it is conceded by engineers that weight reduction is desirable economically but that it is not unusual to find that weight reduction is looked upon as incompatible with reliability and road-holding properties, the author outlines briefly the normal weight-distribution in an automotive vehicle and gives a short analysis of the power required to drive it having in mind the necessity of reducing the absolute friction-loss. The use of aluminum for various parts is debated, especially those in which reliability is distinctly a function of lightness and not of weight such as engine pistons, and the application is made general to cover all parts of an automobile in which the stresses are determined by road shocks and speed. The trend of design in general and recent research in particular are stated to be along the lines of weight reduction without any sacrifice of essentials.

In addition to using a smaller quantity of fuel per horsepower-hour, the small high-speed internal-combustion engine has other important features of advantage which are stated. The authors outline specifications intended to secure these advantages. The high-speed racing engine designed by the authors, which won the 500-mile race on the Indianapolis Speedway in 1920, is illustrated and described in detail, its distinctive features being commented upon. The automobile should be built to a higher standard for the use of the high-speed engine. The builder should work to a greater degree of precision and, as the working parts of the engine are all light and stressed fairly highly, this necessitates the use of properly heat-treated high-grade materials. Few small cars of this type seem to give satisfaction. The authors look for further developments to counteract this in the near future.

Statistics taken from a report made by the Department of Agriculture regarding the number and size of farms in the United States indicate that approximately 2,580,000 farms are available as a market for the isolated gas-electric lighting plant. The common types of lighting plant are classified in three groups, each of which is subdivided into three classes, and these are illustrated, described and discussed. The characteristics of the ideal farm lighting-plant are enumerated and discussed as a preface to a somewhat lengthy consideration of the factors that influence the design of the component parts, which are grouped as pertaining to the engine, the generator, the switchboard and the battery. Storage batteries are still considered the weakest part of the isolated plant and they are specially commented upon. The author emphasizes that much still remains to be accomplished as regards the stability of design, reliability and economy of the isolated plant.

Aviation has no perfect analogy, for it has no precedent. Two classifications are made. Scheduled service includes the carrying of mail, express or passengers on a definite and regularly maintained schedule, independent of, or supplementary to, other forms of transportation. Special service includes pleasure flights, oil-field survey, selecting industrial land-sites, planning cities, aerial photography, forest-fire patrol, visiting remote points, exploration, aerial advertising, delivery of perishable products, real-estate survey and industrial purposes. Each of these classifications requires different equipment, organization and operating personnel. The equipment requirements and the reliability of aerial transportation are discussed, the necessity for suitable terminals and federal flying regulations are emphasized, the subject of insurance is commented upon and the development of aerial commercial transportation is outlined.

The five fundamental criteria of the performance of a motor vehicle as a whole are stated. Riding comfort is investigated at length with a view to determining methods of measurement of the two classes of vehicle vibrations that affect the riding qualities of a car, so that suitable springs can be designed to overcome them. The underlying principles of the seismograph are utilized in designing a specialized form of this instrument for measuring vehicle vibrations, the general design considerations are stated and a detailed description is given. This is followed by an explanation of the methods used in analyzing the curves obtained, thus making possible a standardized measurement of riding comfort. The factors determining riding comfort are then analyzed in connection with spring-development work, the most important are summarized and the preliminary experimental results of those directly determined by the seismograph are outlined.

The two broad divisions of aluminum pistons from a thermal standpoint are those designed to conduct the heat from the head into the skirt and thence into the cylinder walls, and those designed to partly insulate the skirt from the heat of the piston head. Pistons of the first type seem logical for heavy-duty engines; those of the second type are better suited for passenger-car engines. The objections of wear, piston slap, excessive oil consumption and crankcase dilution are stated as being the same for aluminum as for cast-iron pistons; and these statements are amplified. Piston slap is next considered and, as this can be overcome by using proper clearance, pistons of the second design tend to make this condition easier to meet. Many tests show that when too much oil is thrown into the cylinder bores, tight-fitting pistons and special rings will not completely overcome excessive oil consumption.