Telford's practice was to lay a base of large stone on which smaller stones were placed, the surface being made of finely broken rock. MacAdam began with crushed rock a few inches in diameter, and omitted the foundation of large stone. He showed that the angular surfaces of crushed rock, when pressed together by a heavy roller, would give to a layer a few inches in thick ness strength sufficient to sustain the load that is ordinarily imposed on a highway. The MacAdam road was thus lighter and less expensive to construct than the Telford road. The Mac Adam foundation is still used in road building, although there may be a binding of cement and the surface may be a layer of asphalt or of concrete. Great Britain has until recently looked to the parishes and counties to construct and maintain public roads. From 1760 onward parliament chartered a large number of turnpike companies which built toll roads after the crude manner that prevailed until near the end of the i8th century, when Telford and MacAdam began their work. In 1763 a stage coach journey from London to Edinburgh required 14 days.
This situation in Britain was first ameliorated by the construc tion of canals, the first of which, promoted by the duke of Bridgewater to connect Worsley, and thus Liverpool, with Manchester, was opened in 1761. This canal reduced the cost of coal in Manchester 50%. The 3,00o m. of canals constructed in the British Isles between 1760 and 1830, the rapid improve ment of the highways from 18o0 on and the development of railways after 1825 made it possible for England, in advance of other European countries, to market factory-made goods in large quantities at home and abroad, and thus to establish an economic and commercial leadership, which, until recent years, she maintained without serious challenge. England's maritime supremacy was established before the Napoleonic wars, and from 1815 to the present her merchant marine has provided her world-wide commerce with ample transport facilities.
England was not the first country to construct modern canals, Holland began first. France emphasized canal building for two centuries and by connecting her main rivers and improving their channels created a national system of inland waterways. Germany, like France, has made large use of her natural water ways, but their improvement came mainly during the latter part of the 19th century. The waterways contributed to the economic development of many other countries, including the United States during the 19th century, but the role they have played has been a minor one in comparison with those of the railroad, the ocean steamship, and latterly, of the automobile, the bus and the truck.
The Railway, Its Economic Significance.—The introduc tion of the locomotive and the railway inaugurated an economic and social revolution. It gave man the service of a power capable
of indefinite technical development to assist him in expanding his economic activities and his social contacts. The railways, followed and supplemented in turn by the steamship, telegraph, telephone, electric railway, automobile, aeroplane and wireless communication, have during the past 10o years transformed the world. Changes have come with accelerating rapidity until there seems to be no limit to the degree of world unity made possible by developments in transport and communication.
Though it 'would seem that a century of technical progress would have brought the locomotive to the limit of its mechanical possibilities, improvements in power efficiency and fuel economy have been more rapid since the World War than during any pre vious decade. Among the innovations of the last sixty years are: (I) The rolled steel rail which began to be laid about 1870 made possible the construction of a track capable of with standing the strain of the heaviest and fastest trains ; (2) trains could not be safely run at high speed until they were equipped with power brakes. George Westinghouse successfully applied the air brake to passenger trains in and to freight trains in 5887. The air brake reduced by 90% the time and distance re quired to stop a train by hand brakes; (3) the transport of fresh meat and fruit was successfully accomplished during the 1870's with the refrigerator car. Fresh meat from cattle reared on the ranches of the United States, Canada, Australia, Argentina and Brazil has, by refrigeration on land and at sea, been made marketable at all places reached by organized transport. Likewise fresh fruit, and more recently fresh vegetables, are marketed hundreds and thousands of miles from the orchards, vineyards or plantations where they are produced; (4) the operation of freight trains on regular schedule and at increased speed may seem to be a matter of small consequence, but it is placing production and merchandising upon a new basis. The merchant does not now have to carry a large quantity of goods nor does the manufacturer have to stock up with large amounts of materials and supplies. Business is done with a smaller amount of inactive capital, productive activity and the employment of labour are more continuous; (5) as it is by the application of power that the work of transport is done, power efficiency de termines the progress made by transport. The technical achieve ments of recent years give promise of great advances in the future in connection with all transport facilities—railways, electric railways, ocean vessels, motor vehicles, aeroplanes and airships.