IMPROVEMENTS IN ROAD LOCOMOTION.* Two books of great interest to
all who study the "return to the roads" which marks the dawn of the new century lie before us,—one mainly historical, the other practical and prophetic. Mr. Rhys Jenkins draws a lucid picture of the gradual development of the motor-car from the earliest times, whilst Mr. Diplock describes an invention of his own which in the opinion of many good judges, like Colonel Crompton and Professor Hele-Shaw, is destined to revolutionise our notions of the possibilities of traction engines. Both books are very ably written and amply illustrated, and should be placed on the shelves of all who care about the subject which they handle.
Mr. Jenkins deals with the general and historical rather than the technical aspect of his subject, though he is thoroughly well informed on the latter part of it too. He appeals to the general reader, or to the automobilist who wants to know how the motor-cars of to-day were evolved, rather than to the expert who looks for a balanced opinion on the relative merits and defects of various types of car or a critical account of the latest improvements. Thus, instead of again covering ground that has been already occupied by Mr. Beaumont and others, Mr. Jenkins has given a distinctive character to his book by concentrating his interest on the historical aspect of "the application of mechanical power to road vehicles,"—where "historical," of course, must be understood in the sense which Seeley was fond of emphasising, as coming down to the present moment. The most remark- able feature in this history of the motor-car, to our mind, is the fact that only a series of accidents—including the unpro- gressive nature of people who should have known better—pre- vented the road motor from establishing itself in public favour as early as the railway engine. When it first occurred to Trevethick—a remarkable and neglected genius—that the newly invented steam engine, if put on wheels, could transport itself, not to speak of a load, from place to place, he did not think of placing it on rails. The roads were its natural haunt, and the first locomotive which ever transported human beings with success—just a century ago—was a steam motor-car. In the first generation of the nineteenth century a number of inventors, of whom Gurney and Hancock were the chief, con- structed steam coaches which ran with remarkable succesrr. But the opposition of the country gentlemen and the "horsey interest" on the one hand, and of the railway promoters, who foolishly feared competition, on the other, effectually killed the nascent industry, and the motor-car was driven off our roads with such thoroughness that England, which was once a long way ahead of any other country in this department of invention, had to give place to France and Germany and the United States, where legislation did not discourage the young and promising industry when it was revived towards 1885. Mr. Jenkins gives a full account of the growth of the
• (1.) Motor Cars. By Rhys Jenkins. London: T. Fisher Unwin. [21a. net.] —(2.) A Nets System of Heavy Goods Transport on Common Roads. By Brama Joseph Diplock, London: Longman' and Co. Ds. 6d. net.] three main types of motor-car—propelled by steam, electricity, and oil engines—and his well-constructed book deserves a high place in the literature of the subject, besides affording a useful warning of the folly of deterring inventors.
Mr. Diplock's book is a technical but highly interesting and lucid account of the new form of traction engine which he
has invented. Its essential feature is a new kind of wheel, popularly known as the Pedrail, which enables an engine fitted with it not only to draw a much heavier load than an engine of equal power can tackle with ordinary wheels, but to negotiate obstacles that would stop the ordinary traction engine altogether, and even to progress at a fair speed where there is no road at all. The Pedrail cannot easily be described without such diagrams as Mr. Diplock furnishes, but its characteristic is that it solves the often attempted problem of providing a traction engine with its own rails, which it lays down and picks up as it goes along. Mr.
Diplock surrounds his wheel with a number of bearing sur-
faces, something like elephants' feet, each of which carries a roller, and a short rail supporting the load is levered along by
the spokes of the wheel over these rollers. "In an ordinary railway a rail is laid down and wheels are run over it ; in the Pedrail, wheels, or rollers, are laid down and the rail is run over them. The principle is the same, only the railway is inverted. The sliding spoke represents the horse's leg, or lever, and each leg is pivoted by an ankle-joint to its foot."
Thus, among other advantages, Mr. Diplock has enabled his engine to acquire that valuable characteristic of the horse, that for a short interval it can exert a hauling-power out of all proportion to its nominal "horse-power." The feet, of
which three on each wheel are normally in contact with the road-surface, give far more points crappui than the
ordinary wheel, which theoretically only touches the road at a single point. They have the further advantage of automatically adapting themselves to any unevenness
in the surface, so that it becomes possible to climb over
obstacles which no ordinary wheel could negotiate. The advantages of such a system when it is made really practical, as seems to be the case with this invention, must be apparent to all who have considered the question of road traction, and are overwhelming in the case of cross-country work, such as is necessary in military traction, when, for instance, it is a question of taking heavy-guns to a point of vantage. But Mr. Diplock has not only invented a traction engine which is likely to supplant all its competitors, he has also given much thought to the elaboration of a system of road transport for heavy goods, and his modest but invaluable book should be in the hands of every one who is studying this important subject. We have seen nothing to touch it for general good sense and a thorough mastery of detail.
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