OUR COMMON ROADS—MURPHY. 431 
as seem necessary and desirable, having regard to practical worth 
and greatest endurance ; aud thirdly, we require better systems 
of application. All these requirements can only be obtained by 
a knowledge first acquired by induction from facts observed, and 
to the mechanical skill applied in aid of it. 
The formation of public roads and carriage ways, with their 
accessories, bridges and viaducts, was possibly the first manner 
in which the occupation of the engineer was developed. The 
author may therefore be pardoned for introducing the subject by 
reference to the road-making of the ancients, from which our 
systems have to a large extent been gradually evolved. The 
ancient capital of Mexico was approached from various directions 
by paved roads, from two to three miles in length, and thirty 
feet in width. Bernal Diaz, companion of Cortez in his conquest 
of Mexico, so describes it. When the Spaniards under Pizarro 
first invaded Peru, they found, among other indications of civili- 
zation, a net-work of highways superior to those in their own 
country. Roads traversed Quito, passing through Cuzco, into 
the empire of Chili. It is on historical record that there were 
over 1,700 miles of these roads, and that they were paved with 
large flags of freestone, and in many places set in asphaltic cement. 
The earliest roads about which anything definite is known 
are those of ancient Rome, one of which, the most celebrated 
—the Appian Way—commenced 312 B. C. The Roman roads, 
preserved generally a straight course, which is said to be due to 
the convenience of laying them out. Others say they were 
principally constructed with the view of transporting the Roman 
legions, and, like those of Peru, were generally laid out in the 
direct line of route from one city to another, seldom avoiding 
any obstacle, and usually, for defensive purposes, keeping to the 
higher ground. In solidity of construction, they have never been 
excelled, and many of them still remain. Their construction is 
thus described by Mr. Thomas Codrington, C. E.: “Two par- 
allel trenches were first cut to mark the breadth of the road; 
loose earth was removed until a solid foundation was reached, 
and it was replaced by proper material consolidated by ramming, 
or other means were taken to form a solid foundation for the 
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