12-2 THE 



pipes are pivoted upon a supporting arm which holds them 

 iQ position to receive the water from the leader. When not 

 in use the waste pipe is set under the leader and is a little 

 over- balanced by the cistern pipe. A small metal box is 

 fitted to the waste pipe and is connected with it by a 

 small orifice, through which water enters slowly when 

 the rain is pouring from the roof. This box becomes 

 filled in a sufficient space of time for the ram to wash off 

 the roof, and the weight of it then over-balances the 

 cistern pipe, which is brought under the leader and 

 conveys the flow into the cistern. This is a very simple 

 arrangement, and has been found to work very well, 

 needing no attention except to empty the water box 

 after the rain is over and let the waste pipe return to its 

 place. 



Cisterns require careful construction. The best form 

 is the oval or egg-shaped, as this best resists the pressure 

 of the outer earth when it is empty. This form is shown 

 at figure 20. The manner of construction is as follows. 

 The surface soil is removed to a depth of eighteen inches 

 to exclude frost in winter and heat in summer. The 

 excavation is made as shown in the engraving, which is the 

 shape of an egg with the upper third cut off. It should 

 be eight to twelve feet deep, and seven to ten feet in di- 

 ameter. The deeper the cistern the better and cheaper 

 it is. If the soil is close and compact the cement may 

 be laid directly upon it, and no brick lining is required. 

 To do this, a large flat stone (s) is bedded in cement at 

 the bottom for the workman to stand upon, and as a 

 rest for the pump (p). The cement is made of water 

 lime one part, and clean sharp sand three parts ; mixed 

 dry first, and wetted up in small quantities as required, 

 and can be used before it sets hard. The cement is laid 

 about an inch thick (w). When the bottom is covered, 

 a layer is put around the wall about a foot high, and as 

 it sets very quickly, as soon as one strip is laid another 



