adopted. In the instances where it has been employed, the results seem to have been very satisfactory. The wear of heavy vehicles has produced little impression wherever the concrete has been properly laid; and the surface presented is even, and well adapted to the transportation of heavy loads. Appearances certainly indicate that, in point of convenience and durability, the concrete is the pavement for the future.

Palmer's great hotel, the foundation vaults and and first floor of which are of stone and iron only, had just been laid. No wood on the premises. A dealer in sewing-machines was so confident that the arches under the sidewalk of the prospective hotel would be perfectly fire-proof, under any circumstances, that he removed his machines thither so soon as he considered his rooms in danger. They were put into the arches under the sidewalk, protected by great new flag-stones, near a foot thick and seven feet above them. When the buildings on the opposite side of State street burned, although their walls did not fall into the street, yet the air was heated so intensely that these ponderous pavement-stones cracked and broke in every direction, and fell in on the sewing-machines. The work of destruction could not have been more complete had the owner of the machines placed them on the sidewalk beside his burning

store.

ROOFS.

The business blocks of Chicago were covered, chiefly, with paper coated with tar and gravel, a preparation commonly known as felt roofing. Even the "fire-proof" Tribune building was covered with this material, which has been in general use throughout

the United States for a number of years. During the progress of the fire it became very evident that these roofs assisted materially in the spread of the conflagration. The heat was, of course, intense; where adjacent buildings were in flames, the tar melted, and ignition was the consequence; so that roofs which ordinarily resist fire, in this instance were prime aiders in spreading it.

SAFES AND VAULTS.

The experience of the late fire affords much information regarding the relative merits of safes and vaults, for the preservation of papers and other valuables. The work of digging out safes from the ruins, which was begun as soon as the heat of the smouldering pile would permit, resulted in proving the fact that safes, however well constructed, would not, under all circumstances, preserve their contents unharmed. Those placed in wooden buildings, as a rule, held papers and books in good condition; the materials of which such buildings were composed burned so quickly and entirely, leaving nothing remaining to smoulder and retain the fire, that safes did not become heated through. But in buildings of brick and stone the result was more unfortunate. The safes fell among masses of material which burned steadily, and gave forth intense heat for days after the first fire, and thwarted any attempts made at removal. The safes lying in the midst of such heaps of fire became intensely heated throughout, and when efforts to remove and open them were finally successful, their contents were found in many cases to be ruined. Books, papers, and bank-notes still retained their form, but had changed to black in color, and upon

the slightest touch, crumbled into powder. In almost an exact proportion to the length of time they had been forced to remain in the burning ruins, safes were found to have preserved their contents uninjured, or partially or totally destroyed. It is evident that, while a well-constructed safe will hold, uninjured, books and papers, for a time, yet, if remaining in the fire for a long period, no one yet made will fulfill its purpose.

With vaults the result proved entirely different. In nearly every instance, well-built vaults held their contents intact. Bricks and mortar proved excellent non-conductors of heat; and upon the opening of large vaults which stood for some days in the midst of fire, their interiors were found scarcely warm.

The Chicago Tribune suggests the erection, in that city, upon the ball-grounds, of an immense monument to the memory of a number of worthless institutions, late of that city, among which are the various fire insurance companies that proved good for nothing in the hour of trial, the fire-proof safe-builders, whose wares failed at the critical moment, the police and fire departments, so sadly deficient in the time of need, etc. Says our contemporary,

"All over the burnt district the prostrate forms of hundreds of conquered safes are lying, where, having faithfully performed their duties as worthless guardians of property, their ungrateful owners have abandoned them to ignominy. The idea of building a monument from them is novel and unique-more so, perhaps, than the monument itself will be, but we must not grumble at appearances.'

A plan for securing safety for safes, suggested since the Chicago fire, is to support the safe by a rope or

upon a slender platform, directly over a well in the ground. When the rope or platform burns, down goes the safe, where fire can not burn, where thieves can not break through and steal.

THE CHICAGO WATER-WORKS.

Our sketch shows the pumping-house and water

tower. The latter has stood uninjured by the conflagration.

The city of Chicago, it will be remembered, is supplied with water drawn from Lake Michigan, on the shore of which the city stands. As the water around the city, for a considerable distance from the shore, is more or less contaminated with sewerage and other refuse matters, resort was had to a novel expedient to secure a supply of pure water. A masonry tunnel was carried out from the shore, under the bed of the lake, for a distance of two miles. Over the outer end of this tunnel a hollow dock was erected and built up above the surface of the water, and upon it a fine light-house has been erected. Within the dock are suitable valves, by which the pure lake water is admitted to the tunnel. The lake is sixty feet deep where the dock stands. The water flows from the dock through the tunnel to the pumping-houses in the city-shown in our sketch-where it is raised by pumps to a height sufficient to carry it through all the streets and buildings of the city. This remarkable tunnel was begun in 1864, E. F. Chesbrough, Esq., Engineer; completed, and the water let in, during the spring of 1867. Three pumping-engines are employed, rated seven hundred, five hundred, and three hundred horse-power; their balance or driving-wheels twenty-four feet in diameter, and weighing thirty, twenty-one and a half, and eighteen tons respectively. The driving-wheel of the largest engine makes from twelve to fourteen revolutions per minute, and at each revolution raises one thousand gallons of water; its capacity, therefore, is about eighteen million gallons every twenty-four hours, and the average power of the entire machinery is some thirty-eight million gallons daily.