ECONOMICAL TRANSPORTATION. 233 



These pipes are of cast iron, and are manufactured 

 with every possible care, and are submitted to a pres- 

 sure of fifteen atmospheres with water before the juice 

 is permitted to enter. The length of each is 30 m. 

 (98.4 feet). The joint should be perfect, and precau- 

 tion is taken to give an internal and external coating 

 of tar. Their diameter varies with the circumstances, 

 from 65 mm. to 120 mm. Their price per mile is 5000 

 francs ($1000) to 7000 francs ($1400). They are 

 placed in the soil to a depth of 80 c. m. (2.6 feet), this 

 being, in Europe, sufficient to prevent the action of 

 the frost, which depth in America would not be suffi- 

 cient, but 1.00 m. (3.28 feet) we consider would give 

 good results. These pipes follow the general undula- 

 tions of the country over which they pass, and the 

 place generally chosen is the roadside. If the least 

 escape occurs this will be noticed on the surface, as a 

 froth will soon show itself. A superintendent is gene- 

 rally walking to and for, who gives the alarm. ISToth- 

 ing prevents, and it is advisable to have an appa- 

 ratus at each end giving the pressure in the interior of 

 the pipe. If this, at a given moment, should indicate 

 a great decrease, an accident is to be suspected, but 

 these are of rare occurrence. The principal causes are 

 an accumulation of pulp frequently carried with the 

 juice, or, again, by the lime which has not yet com- 

 bined with the liquid. 



Generally certain precautions are taken to prevent 

 these accidents by filtering the juice through chopped 



16 



