By NELSON P. LEWIS,
ENGINEER OF HIGHWAYS, BOROUGH OF BROOKLYN.
One of the conspicuous results of cheapened transportation and the facility with which the products of field, forest, mine, and factory can be transferred to the consumer has been the rapid increase in population of all our cities. In 1890 over forty-five per cent of the population of New York State (nearly six millions) was concentrated in four cities, while it is estimated that the greater city of New York contains at present not less and probably more than fifty per cent of the State's population. Nor is this tendency characteristic only of American cities, though the general impression seems to be that it is more conspicuous with us. In fact, many European cities (notably those of Germany) have outstripped ours in growth. In 1870 Berlin had about 150,000 less people than New York; in 1890 it had over 73,000 more. In 1875 Hamburg exceeded Boston in population by but 6,000, while in 1890 the German city was more than 121,000 ahead.
Meanwhile the rural population the world over has increased very slowly, or has positively decreased. The massing together of large numbers of people, without proper regard to sanitary conditions, has always resulted in great mortality, as witness the terrible plagues which have swept over the old cities of Europe, and the disastrous results during the summer of 1898 of concentrating large numbers of our volunteers in camps not subjected to rigid sanitary regulations.
It has been amply demonstrated, however, that our cities can be made at least as healthful as the country districts, and an increasingly large number of engineers are engaged in such city building.
One branch of this municipal work will be considered in this paper—that of street improvement. The first impression gained by a stranger entering a city is undoubtedly that produced by the appearance of its streets. If they are poorly paved, irregular, dirty, and generally unkempt, he will consult his time table to see how soon he can get away. If they are broad, smooth, clean, well shaded and lighted, he will stay as long as possible.
In spite of the pride of the American people in the development of our cities, and notwithstanding the fact that their wealth enables them to have only the best, they have been slow to appreciate the value of thoroughly well-paved streets. As stated by Mr. Albert Shaw, European cities have been ahead of us in accepting the doctrine that "smooth and clean highways are a wise investment from every point of view, and that so long as the work is done in a thorough and scientific manner the result is worth having, regardless of cost. No city should think itself rich enough to prosper without them, and no city is so poor that it can not afford them if it has any reason whatever for continued existence. Good roadways are cheap at any cost, and bad ones are so disastrously expensive that only a very rich country, like the United States, can afford them."
Space will not permit even a brief history of street paving, or an attempt to sketch its development, but reference will be made to the different kinds in general use, and the kind most in favor in various cities. Probably no one has introduced the subject of pavements without reference to the Roman roads.
While Carthage was probably the first city to boast of paved streets, the Romans soon followed its example, and all over Europe, Asia, and Africa, as far as the domain of their emperors extended, they built with the greatest care and at enormous expense that magnificent system of roads which were often supposed, in the middle ages, to be of supernatural origin, and remain the wonder of our modern civilization. These roads were generally from four to six metres in width, and were constructed in this way: The roadbed was excavated; in it was placed a layer of stones, which were sometimes united with mortar. These stones were such as were most available, sometimes rounded stones similar to the cobblestones with which we are familiar, and in some cases in the Alps the foundation was a compact mass of angular stones, two feet or more in their longest dimension, carefully fitted together.