134 THE BOULEVARDS. 



it is somewhere about lOflf. per superficial foot for quan- 

 tities not less than 700 feet. For roofs and terraces to 

 the same extent, the cost would be about 2c?. extra. 



During the last few years the preparation of the asphalte 

 in Paris has been much improved. Some years ago, when 

 a pavement was to be made with bitumen, a great nuisance 

 was experienced by the public during the operation. The 

 mastic was liquefied on the spot, and produced a nasty 

 smell and smoke, disagreeable and injurious ; but now some 

 of these inconveniences have been done away with by a new 

 system, and asphalte is now laid down in the most expedi- 

 tious manner. It is prepared first in out-of-the-way places 

 devoted to the purpose, and the matter, ready for use and 

 liquefied, may be transported from these places to any 

 parts of the town without the least inconvenience in a semi- 

 cylindrical boiler, closed by iron doors, and moved about on 

 iron wheels as freely as a common cart. Under the boiler 

 is a fireplace, and the blaze, after having heated the two 

 sides of the boiler, passes out by a chimney placed at the 

 back of the machine. Means to keep the mastic in motion, 

 and prevent its burning by adhering to the sides of the 

 boiler, are secured by a simple mechanism easily worked 

 with the hand. These carriage boilers, full of liquid asphalte, 

 are driven from place to place with the greatest facility. 

 The boiler is emptied by the means of a pipe fixed to its 

 bottom, and the mastic is collected in a pail, and spread 

 on the surface to the thickness of three-quarters of an inch. 



If the surface is not perfectly dry, the drying must be 

 accelerated with hot ashes, which are to be taken away 

 afterwards, or with a little spreading of quicklime in 

 powder. These operations are indispensable, as if the 

 mastic were laid on before the surface is dry, the heat 

 of it would dispel in steam the water underneath, 

 and that steam would produce blisters in the asphalte, 

 which would crack under the pressure of the feet, and 

 endanger the success of the operation. The workmen 

 place on the platform two iron bars of the same thickness 

 as the asphalte is to be, equally distanced from each other ; 

 it is then laid down in a very warm state, and thick 



