76 



Indiana University Studies 



formula for determining the size of shell needed for a given horse- 

 power: 



Area of the shell of heater = Horse power — 



a X length in feet 



In this formula a = 2.15 for very muddy water; a = 6 for 

 slightly muddy water; a = 8 for clean water. 



Cochrane Feed-Water Heater and Purifier 



