6 



The Water Supply of Constantinople. 



six feet in a second. It has been calculated to be able to 

 supply 6,000,000 of gallons in twenty-four hours. 



In the winding course of the canal towards the south, there 

 are several breaks or alterations of level, said to have been 

 devised for the sake of exposing the water in its fall to con- 

 tact with the air. Branches go off from it to villages on 

 the Bosphorus ; and as it approaches Pera on the hill, its 

 water branches off to four or five villages of which it is the 

 centre, from a receiving reservoir 200 feet square. 



No one of the engineers of these aqueducts availed him- 

 self of the fact that water would safely run in pipes and 

 channels having curves of rise and fall. They had not a 

 knowledge of the strength of cast iron pipes, and could only 

 use lead, or tiles joined with cement, which might yield to 

 the pressure of the column of water ; and this may have 

 been the sufficient reason for their choosing to depend on 

 a uniform descending flow of the water. There was an 

 experiment, however, which they tried in bringing the 

 water of this aqueduct to the city, which has been uniformly 

 noticed by travelers, and the reason for which it is difficult 

 to understand, nor have I ever known it to be satisfactorily 

 explained. When the water canal reached the edge of a 

 valley which it must necessarily cross, it was allowed to 

 descend the hill to the foot of a stone column thirty to 

 seventy feet high according to circumstances; then a pipe 

 of lead conveyed it to the top of the column into a small 

 open basin ; from this basin it overflowed into a second 

 pipe likewise open at the top, and descending passed under 

 ground some hundred feet to a second column of the same 

 height, where the same process was repeated ; and so on 

 till the top of the opposi te hill or rise of ground was reached. 



As Ave know that the water could in no case rise higher 

 than the level of the last column from which the water had 

 flowed, the question arises what advantage did the en- 

 gineers expect to gain by the contrivance ? Did they be- 



