402 



THE VILLA GARDENER. 



474. Tlie pipes that convey the water from the reservoir to the jet should be 

 laid, as nearly as possible, in a straight direction ; and that part which is under 

 ground should be sufficiently deep to be out of the reach of frost, and of one 

 uniform slope from the reservoir to the jet. In proportion as the direction of 

 the supply pipe is circuitous, and the level irregular, will the friction of the 

 water be increased when in motion, and consequently the power of the jet 

 diminished. There are two other evils which result from not laying the pipes 

 on a uniform slope: viz., that air will collect in all the higher parts of the 

 pipe, and mud in all the lower parts ; so that, for each deviation, upwards from 

 the uniform slope, it is essentially necessary to have a small pipe with a cock to 

 permit the escape of the air from time to time ; and in the lowest part of every 

 deviation from the uniform slope downwards, a pipe is also necessary with a 

 cock to admit of occasionally, say once a year, washing out the mud. Few 

 persons are aware how very soon air collects in water pipes ; or how much 

 sediment is deposited by even the purest water ; which sediment is generally 

 difficult to remove, in proportion to its fineness. We have known fountains 

 that in a very few months after they were put up have ceased to act, owing 

 solely to the accumulation of air in their pipes ; and in other places, where 

 old fountains, after having played for many years, have ceased to act, the 

 cause is to be found in the accumulation of air and sediment. Much more 



