ORIGIN AND USES OF ASPHALT. 



541 



tinued to insinuate itself through the pores of the limestone, and to 

 fill its infinitesimal cavities. 



Mineral asphalt is relatively a soft stone. It becomes more com- 

 pact as the temperature diminishes, but yields under the influence of 



heat to such a degree that an exposure of a few days to the summer 

 sun will sometimes cause it to crumble. This property has induced 

 the application of the compressed material to the making of pavements. 

 Its fitness for this purpose seems to have been suggested by accident. 

 When the mineral was first quarried, the pieces which fell along the 

 road from the wagons carrying it were ground up by the wheels, and 

 were finally compressed again by the continued passage of the wagons 

 over the dust, so as to form a kind of spontaneous pavement. A Swiss 

 engineer, M. Merian, acting upon the suggestion of this incident, as- 

 phalted a part of the road from Travers to Pontarlier, in a rough way, 

 but with a satisfactory result. In the next year (1850), M. Darcy, in- 

 spector-general of bridges and highways, recommended asphalt as a 

 material for pavements in a report to the Minister of Public Works. 

 The first asphaltic pavement was laid in Paris in 1854. 



