224 SEWER DESIGN 



nection with the discharge of sewage onto filter beds has given 

 a great impetus to the use of flush-tanks, and their reliability 

 has been much improved. The question of the propriety of 

 their use for the purpose of cleaning the upper ends of laterals 

 is discussed in the next chapter. 



PROBLEMS 



87. In the tipping bucket of the Van Vranken flush-tank, assume a 

 definite geometrical shape and locate the proper centres of support, con- 

 sidering the bucket both empty and full. 



88. In the Miller tank, determine the relation between the head of 

 water in the tank and the length of the lower limb of the siphon. Is 

 any other factor involved in fixing the depth of water in the tank at the 

 instant of discharge? 



89. Determine the time (approximately) for the discharge of a flush- 

 tank, 4 feet diameter, 2\ feet deep through a 6-inch siphon. (Consult 

 catalogue for dimensions). 



