120 



FARM APPLIANCES. 



but should be filtered as soon as it falls. The main cis- 

 tern, figure 144, is made egg-shaped, to hold one hun- 

 dred barrels. The filter is flat-bottomed. The end of 

 the pipe from the filter to the cistern is built solid 



a 



Fig. 146. A HOUSE FILTERING CISTEBN. 



around the end with brick. All water has to pass 

 through the brick. The filter is filled half full with 

 charcoal, sand and gravel in layers one layer of each 

 the charcoal covering the bricks, then sand and gravel 

 on top. The water, as soon as it falls, begins to filter 

 and passes into the cistern, where it stands free from 

 impurities. The filter is built to hold twenty-five barrels 

 of water, but is half full of the filtering material. 



Figure 145 shows a good filter for a barn cistern. The 

 top of it consists of broken stones, with a flat stone to 

 receive the influx, so placed as to prevent heavy rains 

 from disturbing the broken stones. This has a cover, 

 movable in part, to permit it to be cleaned out occasion- 

 ally. Figure 146 is a filtering cistern for a house. The 

 inlet pipe is at a, the draw pipe is at c. and this is con- 



