of innovations which merit detailed description because they are found on many automobiles of late models. Other works dealing with automobile construction published in the past, make no reference to these improvements owing to their recent development. Among these may be mentioned torpedo and other symmetrical body forms designed to overcome air resistance; sleeve valve motors, a general adoption of the selective sliding gearset in the three and four speed forms, the adoption of shaft and bevel gear drive on even the heaviest pleasure vehicles, the increasing tendency to favor worm gear power transmission, the universal application of magneto ignition and development of electric lighting systems.

There is also more consideration of left hand control, growing use of unit power plants, wider application of block motors and two bearing crank shafts, and a better appreciation of the advantages of the underslung chassis. The I-beam section front axle is almost universally used, and there is marked improvement in multiple disc clutches, wider application of practical self-starters, and more general adoption. of ball and roller bearings at all points. The use of long stroke motors, offset cylinders and automatic lubrication systems make for pronounced increase in automobile efficiency. There is also an augmenting tendency to place change speed gearing on the rear axle, toward the use of three-quarter springs for rear suspension, supplying larger wheels and tires as well as quick detachable wheels and rims. Some of the foreign tendencies which may influence domestic design. are a return to wire wheels by some of the leading European engineers; the application of silent chains for valve operation, in change speed gearing and even final drive and use of front wheel brakes.

In addition to these final improvements may be added a better realization of the advantages of alloy steels, a universal tendency to weight reduction, and increase of power to weight ratio. The floating rear axle has almost entirely displaced the simpler form and marked improvement is noticed in carburetor construction owing to changes in grade of fuel now supplied which impelled the development of multiple jet and compensating vaporizer forms. Many novel and practical accessories have also been developed.

In order to make this work wide in scope, not only will principles of construction and operation be discussed comprehensively, but many

examples from contemporary foreign and domestic practice will be given to amplify the subject and increase the reader's opportunity for the acquirement of a practical motoring education. The illustrations have been carefully prepared, and for the most part the cuts detailing construction of the various components are reproduced or adapted from actual working drawings and thus are true outline representations of the objects described. As previously stated, it is believed that a concentration of effort in treating exclusively of vehicles propelled by internal combustion motors will make this treatise. one of more practical value to the majority of motorists than any heretofore published.

The repair hints and suggestions given for maintenance and equipment are based on a wide practical experience which dates since the inception of the industry as a designer, repairer, and operator of motor vehicles, and should be of exceptional value to those who have not had an opportunity to become familiar with automobiles but who can apply the experience of others to good advantage.

THE AUTHOR.

THE

MODERN GASOLINE AUTOMOBILE

CHAPTER I

Defining Trend of Modern Practice-Explaining Important Components of the Motor Car and Considering Functions of Each Group of Mechanism.

DURING the past decade great progress has been made in all branches of engineering and science. This is especially true in mechanics, and one of the most notable achievements has been the advancement of the self-propelled vehicle from a crude and unsatisfactory construction to one of great refinement and practicability. In ten years the growth of the automobile industry stands unparalleled in the industrial history of the world. One familiar with the improvement of the motor conveyance during that time and who remembers the early types marvels at the refinement of detail and the changes in design which exist in the vehicles of the present day. The modern gasoline automobile fills every need as it is comparatively light, powerful enough for all road conditions, easily controlled and capable of running for thousands of miles without adjustment of the mechanism. It surpasses the powerful locomotive in speed and reliability, and has a radius of travel greater than any other conveyance.

There are numerous standard principles upon which motor-car construction is based, and some of these differ from each other radically, both in theory and practice. Many constructions, if looked at from a purely academic point of view, will appear to possess advantages which cannot be questioned, though on further consideration a car of apparently inferior design which does not have the same method of accomplishing a like object may be a better seller and a more popular car among motorists.

The tendency of the motor-car designer of the present day is toward simplicity and increasing efficiency of the mechanism. There

are many rules of practice leading to this end generally known to engineers, though not accepted by all as the best methods of construction for motor vehicles. It is the writer's purpose to review all the types of the various automobile components that have merit, and the qualities of each design will be given as stated by those favoring it. This is not intended as a criticism, but to enable the motorist not informed regarding details of motor-car building to make intelligent comparison with other forms.

Within the last few years the design of automobiles has been considerably changed, and the difficulties that previously retarded development have been for the most part eliminated by modern automobile engineers. This gradual modification of the automobile from a crude mechanism to a practical product has been attained without radical changes that many confidently forecasted at the inception of the industry. The essential elements of the motor car of to-day remain practically the same as far as basic principles of design are concerned, as those which formed the basis of the first motor car. Only the details have been changed and the forms which have resulted from the gradual process of evolution show a steady tendency toward uniformity of design.

Important Components of Modern Motor Cars. In this era of progress, one would hesitate to assert that the motor car had been perfected or that it had reached a finality in design, though the experience of the last few years would justify one in assuming that the principles of construction now applied so successfully may reasonably be considered permanent. The elements which have been proven essential to insure successful operation of all self-propelled conveyances may be easily defined as follows:

First: The endeavor of modern constructors is to make all operating parts of such material, size, and strength, that the severe strains imposed by the rough nature of the average road surface will be resisted adequately and to secure endurance and serviceability under all possible conditions of operation.

Second: The mechanism should be as simple as it is possible to make it, as this promotes ease of repairing, facility in handling, and lessens the liability of trouble by reducing complications. The parts should be in proper proportion and arranged in such a manner rela