DRAINAGE, 49 



but for the former purpose it should be filtered, as it it likely 

 to collect impurities from the roofs; sometimes, by upward 

 filtration through sand and gravel, the tank itself may be made 

 to perform this duty. 



The Author cannot pass from this section of his subject 

 without dwelling for a moment upon the imperative necessity 

 of the strictest supervision whilst the pipes for drainage are 

 being Ir.id, for errors may be then committed which cannot 

 always be afterwards detected, and if capable of repair, are only 

 so at considerable inconvenience and cost, when the drains 

 are covered in and the yard and stables are paved, and a great 

 many, or may be all, the pipes are under concrete. 



E 



