Buildings and Yards. 



521 



highest, of iron. Lead pipe three-fourth inch in diameter costs about ten 

 cents per running foot and is rarely used in these days. 



WeUs may be artesian, deep or shaUow. ( i ) Artesian wells are those 

 which reach a porous stratum, passing through an impervious stratum, 

 the water being held under such pressure that it raises to the surface in 

 the well pipes, often with force enough to flow into the second story. 

 Such wells are either bored or driven. (2) Deep wells are similar except 

 that the water does not reach the surface and has to be pumped, sometimes 

 from extreme depths. (3) Shallow wells are driven, or merely dug, into 

 an underground stream, the water from which is pumped by simple 

 pumps. 



Fig. 318. — Small hydraulic ram, pumping water brought doivii from a small spring. 

 IVIicn all conditions arc perfect, the ram is satisfactory. 



It is safe to say that pumping is to be resorted to only when there is 

 no chance of getting a gravity supply of approved purity at a reasonable 

 cost. This is true for two reasons: (i) Daily charges for maintenance 

 are very likely to represent a large amount of capital invested. For ex- 

 ample, — if the cost of pumping were only ten cents per day for fuel, not 

 counting the labor, it would amount to $36.50 a year, which, at five per 

 cent, is the interest on $730. It would be $200 cheaper, therefore, to 

 borrow $500 at five per cent to pay for a gravity supply than to pay $30 



