308 LIGHTING BY GAS. 



the establishment of the next customer, whose receptacle, 

 being empty, would be ready to take half of that which 

 still remained. Thus, while the cylinder in the wagon 

 would deliver five atmospheres at the first customer's, it 

 would deliver two and a half, which would be half of the 

 remainder, at the second, and so on. In this way, with 

 proper management, a large portion of the load could be 

 delivered, and the residue, which was not delivered, would 

 not be lost, but would remain in the cylinders as so much 

 toward the next filling. 



The plan, however, after all, was not found to be practi- 

 cally successful. There were so many difficulties and in- 

 cumbrances to interfere with the easy and convenient 

 management of it that it never was carried into extensive 

 operation. One good, however, results from the experi- 

 ment : it affords an excellent illustration to aid the young 

 student to understand the nature and the operation of 

 pressures, and the modes of measuring them, and Law- 

 rence made very good use of it for this purpose in hie 

 conversation with John. 



