the stuff has been dumped on the states, apparently as the best way of getting rid of it. To look a gift horse in the mouth is not considered good form, but it must be confessed that frequently the state can find no use whatever for the good things showered upon it.

Consider again the enormous quantities of material which will be used this year in surfacing the roads, and the number of men who will find employment in its preparation and transportation. Figures make dry reading and averages are sometimes deceiving, as in the case of the man with two beautiful daughters. One was very bowlegged, and the other decidedly knockkneed, but they averaged all right, as the father pointed out. A few figures, however, will be necessary to give us some idea of what a billion dollars of road construction

means.

Probably 60 per cent of the billion dollars, $600,000,000, will be used for the construction of hard-surfaced roads -gravel and the higher types. Concrete roads eighteen feet wide will cost about $30,000 a mile; gravel roads, from $10,000 to $20,000 a mile, according to their width-an average of about $20,000 a mile. Our $600,000,000, therefore, will build 30,000 miles of hardsurfaced roads, enough to reach around the earth and from New York to San Francisco and back again.

To surface the roads of various types will take an average of 3,000 cubic yards of material to the mile, about 90,000,000 cubic yards altogether. All this material will have to be hauled an average of two miles from pit or railroad to the job. Something like half of it will be shipped in by rail (45,000,000 cubic yards) in cars containing approximately 30 cubic yards each, 1,500,000 cars, 40 feet long from bumper to bumper, forming a railroad train more than 11,000 milesIt makes one's head ache.

The stone or macadam road, which was such a favorite until recently, is not new to our civilization. We are told that explorers in Egypt, endeavoring to find out how the ancient Egyptians were able to build the Pyramids, were astounded at the remains of roads discovered. "These roads were constructed originally very much as our roads are built to-day," says Doctor Fisher of the University of Pennsylvania. "The rightof-way was leveled; the large stones were packed in. On top of these were placed layers of stones gradually diminishing in size until the finely ground stone of the surfacing was placed. This was wetted and pounded, probably by hand, until the top presented a smooth surface."

Over such a road from an alabaster quarry at El Amara to the Nile, a distance of eleven miles, thence by water

to Memphis, two hundred miles, and by road again, huge blocks of quarried stone were transported, pulled on sleds by man power, it is thought, over the pavements, wet to make them slippery. These roads were of a type which we have come to call water-bound macadam. It has taken us five thousand years to improve on those old Egyptian roads.

Modern paved roads which are superseding macadam are built of concrete, or with brick or bituminous surfacing on a concrete base. In the most expensive types the concrete is reinforced with steel. The tendency of state engineering departments, moreover, is to build

them much as modern railroads are built with low grades, few curves, and without grade crossings. Indeed, there is a close analogy between railroad and highway developments. The railroad, in pioneer days, like the highway, followed the line of least resistancearound or over hills instead of through them. Within the past twenty years, to secure greater economy of operation, railroads have spent millions in cutting out curves and grades, which modern earth-moving machinery has made possible. More and more will road building take the same course. In the reconstruction of the Miller Trunk Highway leading from Duluth, Minnesota, into

the Mesaba Iron Range, now being paved with concrete, 4,800 degrees of angle have been cut out in sixty miles. This is an extreme case, practicable only in an undeveloped country, but it illustrates the tendency.

Concrete road construction is an industry in itself, and a comparatively new one. Few who experience the joys of motoring over such a surface know, except in a very general way, how such pavements are produced. To understand their construction we first must know something of the nature of con

crete.

When mixed with water, Portland cement hardens into something resembling stone, and particles of stone and sand which have been coated with this mixture become fixed in a solid mass. In the manufacture of road concrete grains of sand and pieces of crushed stone, or gravel, in desired proportions, are thoroughly coated with a paste made of cement and water, and the plastic mass thus formed is spread upon the roadbed, where it hardens. To coat

It

the sand and stone with the cement paste, a machine with a revolving drum has been devised, called a mixer. is something like a gigantic ice-cream freezer. Into this mixer sand, stone, and cement are thrown in right proportions, a stream of water is turned in, and the "batch" is stirred and revolved for a period of usually one minute. At the end of that time the mixture has become plastic concrete, whereupon it is ejected upon the road, there to be shaped and left to harden.

Until recently it has been the practice to charge the mixer from piles of materials distributed along the subgrade, handling the materials in wheelbarrows -so many loads of stone, so many loads of sand, and so many bags of cement, in each batch. This method is still used where labor is cheap or other local conditions make it desirable. The need for greater production, for an unrutted subgrade, and for lower costs is driving the larger road-building contractors to the mechanical handling of paving material.

The modern method is this: Cars of material which have been shipped in are unloaded into bins by machinery, at a convenient siding. Small industrial trains, operating on a track of 24inch gauge and carrying batch boxes, are loaded by gravity under these bins with measured portions of sand and stone. The load is completed by the addition of the required amount of cement. Hauled by a gasoline locomotive, the train speeds off to the mixer, two miles, three miles, sometimes four miles away, track having been laid along the shoulder of the road. When the job is reached each box is lifted by crane and swung over to the mixer, where the batch is discharged by gravity through bottom drop doors. Another method, which some highway departments will not permit, is to install a central mixing plant and transport the plastic concrete, usually in trucks, to the road which is being paved.

There are 206 concerns in the United States which make cement for road building, with an annual output of 125,

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000,000 barrels. Add to these 127 concerns which manufacture paving brick; 46 which make wooden paving blocks; 23, granite paving blocks; 380 dealers in crushed stone; 42 manufacturers of asphalt, and 340 firms which ship 23,000,000 tons of sand and gravel each year-and some idea may be gained of the meaning of the comprehensive term, 'road-building industry." The annual production of these concerns amounts to more than $450,000,000. In addition to these, are the manufacturers of grading, road-building, and transportation equipment, employing many thousands of men. Eighty thousand federal, state, county, town, and city highway officials are now identified with this great industry, not to mention the engineers and

contractors.

Government tests show that the "pull" required to move a gross load of one ton over a level road is as follows: Loose sand road, 315 pounds; average dry earth road, 150 pounds; firm earth or sand-clay road, 105 pounds; average gravel road, 80 pounds; first-class gravel

or macadam road, 55 pounds. As there are still more than two million miles of earth roads in the United States, the figures are startling.

Our public roads of varying types, good, bad, and indifferent, constitute the primary means of transportation of all agricultural products and for much of the production of mines, factories, and forests. More than 350,000,000 tons, it has been estimated, are handled over the roads of the United States each year, at a prevailing cost at the time the figures were made, of twenty-three cents a ton per mile, the average haul being eight miles. This brings the annual cost of hauling up to the approximate total of $650,000,000. The cost of hauling over hard-surfaced roads, we are told, ought not to exceed thirteen cents a ton mile. These figures being correct, city and town people who buy farm products thus pay, as part of the expense of distribution, an excess cost amounting to ten cents per ton mile.

Five two-ton trucks carrying full loads were driven over various types of road some time ago, to determine the mileage per gallon of gasoline. If America has gone road-crazy, as some claim, these tests seem to show method in her madness. The mileage per gallon of gasoline on earth roads was 5.78; fair gravel, 7.19; good gravel, 9.39; fair bituminous macadam, 9.48; fair brick, 9.88; good brick, 11.44; concrete, 11.78.

It is impossible to consider this era of road construction apart from the development of the automobile. Each has reacted on the other; together they form an interesting phase in our social and economic progress. They have eliminated time and distance to a remarkable degree. They have brought the farm close to the city.

The great "trails" which have been laid out across the country from north to south and east to west will have other economic values, but they are being developed primarily to attract automobile tourists, and already are attracting them in countless thousands. The road

building activities of the various states are often planned with tourists in view. California's superb roads are among that state's chief assets. Michigan, with a myriad of small and beautiful lakes difficult of access because of sandy roads, is building a splendid system of graveled and concrete highways which will make the state a great playground for the Middle West. The same is true of Minnesota. North Carolina, with her unsurpassed Blue Ridge Mountains and delightful climate, is spending millions for good roads in the expectation that the tide of travel will turn that way. Ten million dollars will be spent by the State Highway Commission alone this year. Florida, already a winter play ground, is making it possible to traverse her almost impassable sands on hard roads, down the east coast, up the west coast, in various directions through the interior, and even is building a great highway through the historic Everglades.

An English engineer has criticized mildly the narrowness of concrete roads in the United States, 18 feet being the standard width, whereas the exigencies of safe traffic, he says, call for pavements 30 feet wide. He is right, of course, but insistence on 30-foot pavements in this country would arrest our road-building movement in its infancy. Taxpayers would refuse to authorize the necessary bond issues, were the cost nearly doubled. The crying need in America is length of good roads, not breadth.

There are, in round numbers, 2,500,000 miles of public roads in the United States. Earth roads comprise about 892 per cent of this mileage; sand-clay roads, 2 per cent; gravel, less than 5 per cent. At the time these statistics were gathered by the government, some five years ago, there were only 110,000 miles of all other types of road combined, constituting about 4 per cent of the total. Of this mileage a few great highways stand out conspicuous because of their scenic beauty, great cost, or the engineering difficulties involved in their