PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 513 



In publisliiug this idea of a traveling' furnace to pour melted lava or 

 iron upon the road, and a roller to surface and chill it, I wish it to be under- 

 stood that I do not abandon my claim to a patent for whatever is original 

 in it. I publish it for the purpose of obtaining' aid to determine whether 

 the design is worth pursuing; and, if worth pursuing, to invite the coope- 

 ration of engineers and capitalists, and others who may help to promote 

 it. How much of it is new, and how much of it may have been known 

 before, I cannot now say. 



It may be objected to this plan, as it was objected to Barlow's con- 

 tinuous rail, that the expansion and contraction due to changes of tempe- 

 rature will work the iron or lava. But in the case of Barlow's rail, and 

 others similar to it, it was found that the elasticity of wrought iron was 

 sufficient to compensate for the efi'ects of temperature; and that, practi- 

 cally, there was little or no difficulty from contraction and expansion, even 

 in split rails, where, at points, only half the section of metal was available 

 to resist the force of contraction. In case of a continuous sheet of cast 

 iron, of even breadth and thickness, or equal cross section, there would be 

 less liability to derangement; because, first, the whole length would 

 stretch to the extent of its elasticity before rupture or permanent set would 

 occur at any point; and, second, because the elasticity of cast iron is 

 greater than that of wrought iron, in the proportion of seven to six. Com- 

 pared with a line of continuous split rail, like that for a long time used on 

 the New York Central railway, a continuous cast iron road surface would 

 bear a charge of 140 degrees as well as the rails would bear a charge of 

 60 degrees, or it would bear a charge of 280 degrees as well as the rails 

 would bear 120 degrees. But it is not absolutely required that the road 

 be continuous; there may be slip joints at intervals, if there be much diffi- 

 culty in making it solid. Even cracks, such as might occur in a road 

 made without skill, would be trifling when compared with the defects of 

 the best pavement we have at present. 



If these ideas be correct, it is practicable to pass a movable foundry 

 through a street, upon a temporary railway, leaving behind it a floor of 

 cast iron, either smooth, or. indented to prevent slipping, and shaped to 

 secure drainage. I think the whole surface, from house to house, should 

 be made at one operation, and the ups and downs at crossings should be 

 avoided, as they are in Naples, Florence, and other cities that are paved 

 with stones like those of our new sidewalks in Broadway. And access to 

 sewers and pipes should be from the sides, and not down from the surface, 

 as was proposed by the London engineers twenty years ago. 



The cost of cast iron paving on this plan would, I believe, be much less 

 than that of cast iron laid in pieces. There would be no displacement, 

 and repairs would not be required, except in cases of breakage, which 

 ought never to occur. And we have had practical proof, from Scotland, 

 that cast iron paving remains apparently uninjured after good stone pav- 

 ing, subject to the same traffic, has become unfit for use; and that the 

 annual cost of the iron is less than half that of the stone. Could we sum 

 up the cost of relaying, incumbering the streets, repairing, cleaning, the 

 waste of motive power, damage to carriages and their loads, wear of shoes, 



[Am. Ins.] 33 



