DRAINING OF THE POND OF CITIS. C) } 



horizontal gallery is carried to the pond at the distance of 320 asteam engine, 



— ,..' T, ' , 1 , .1 ^ andforcinff the 



feet. This gallery, or rather aqueduct, conveys the water ^^^^^ through 



from ihc jiond into the well. For this purpose it was neces- a cylinder 450 

 sarv, to arch it over completely. In the well are two pumps, j),g ^^ ^^ ^1^^, 

 and close to it is the steam engine, which works thejii both lii^'* 

 alternately by means of a double crank. Adjoining the 

 pumps in the well are two vertical pipes, communicating with 

 them, and united at the mouth of the well by means of an 

 -elbow, or fork. The part where they unite is fitted to a cast 

 iron cylinder, 450 feet long, carried up the slope of the hill. 

 'J'his hill not being so high as some of the following, it was ne- 

 cessary to raise'the cylinder upon supports of mason work to 

 form a common level. A wooden trough, supported by tres- Thence ^con- 



sels, unites the first hill to the second. This is 895 feet long. "^V^^ ^Y ^ , 

 , , • , • If r I • 1 • wooden trough 



At the end of this trough begins a canal ot 2494 leet, which is 895 feet \m<r 



cut in the rock to the mean depth of 9| feet. To unite the ^o the next 



:- ,, , , •,. • 1 , 1 "i"; ^"d by a 



summits of all these lulls it has been necessary to erect several canal with oc- 



aqueduct biidfjes, over which the canai is conveyed. I'he ';^^'°'''^.^,^'l"'^" 

 . , , ..,.,, duct bridcres to 



canal might have been cut to less depth, by raising higher the the sea. 



iCast iron cylinder, and consequently the wooden trough; but 



,the wind already has sufficient hold of both these, and they 



.could not fail to have been weakened, had they been raised 



liigher. ii the iron cylinder had been made to rest on the hill, 



in order to dispense with the wooden trough, the canal must 



Jbave been cut to an extraordinary depth, or a gallery of 2500 



feet must have been cut through the rock, which would have 



occasioned an enormous expense. 



The steam of the engine acts upon the pumps, which draw 

 Jap the water of the welj, and force it into the vertical pipes, 

 'i'hese convey the water to the ascending cylinder, in which 

 it rises gradually to the top of the first hill, whence it flows 

 through the trough into the canal, which discharges it into 

 the sea. 



The water contained in the cylinder acts with all its weight The engine 

 on the valve, that separates it from the fork of the two pipes : gives 32 



, . , r 1 • 1 I r sf'okes in a 



yet such is the power ot the engine, that at every stroke, ot minute, rais- 



which it makes tiiirty-two in a minute, it not only raises a '"? '^^^^ l^**' 



.... of water in the 

 certajii quantity of water into the vertical pipes, but gives it cylinder. 



a prcs- 



