
2 TECHNOLOGY. 
subjects and discussed them more at length, in preference to giving some- | 
thing of all without treating fully of any. 
One of the principal means of advancing civilization is facility of com- 
munication, by which men are brought together and the products of one 
region are speedily and safely transferred to another; the interchange of 
ideas as well as the exchange of the productions of nature and industry 
being thus promoted and facilitated. We therefore place at the head of our 
treatise the means of communication. 
I. MEANS OF COMMUNICATION. 
Means of communication include the construction of highways on land 
and water. The welfare of a state is greatly promoted by a well regulated 
system of roads and inland navigation, and it is easy to discover the dif: 
ference in the civilization, industry, and general opulence of two countries, 
in one of which communication in all directions is made easy and convenient, 
while in the other cities and villages are in a measure isolated by the bad 
condition or want of highways. How much has been effected in this respect 
by the construction of railroads in the greater part of Europe and in the 
United States need scarcely be mentioned. We will now proceed to consider 
the different kinds. 
1. Tae Construction or Roapbs. 
The natural surface of the ground, unless it be rock, when used as a 
road, is soon brought to such a condition by the action of the weather and 
of vehicles as to offer great obstacles to convenient communication. On this 
account artificial roads have been constructed since very ancient times, and 
remains of such which have been preserved to the present time show how 
carefully and judiciously they were designed. The first highroads of 
which we have any knowledge were built by Semiramis, and one of them 
led from Susa to Sardis, a distance of 2100 miles. The Carthaginians also 
had artificial roads, and the oldest in China were built so durably as to be 
still available. The Greeks, especially the Athenians, constructed excellent 
roads, particularly for their religious processions, as for instance the sacred 
road of Eleusis, and that to Delphi; there was also such a one near 
Cyrene. 
The Romans, especially in the reigns of Augustus, Vespasian, and 
Trajan, constructed causeways from the city of Rome to all parts of the 
empire, however difficult the ground, all of which radiated from a central 
column (melliare aureum) and were divided into miles of eight stadia each. 
They were built with extreme care, and remains of these Roman roads are 
found in almost all parts of Europe. They have below a bed of mortar 
substratum) of about one inch in thickness; on this rests a stratum ten 
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