THE STRESSES IN A STEEL WATER-TOWER. Ill 



termined readily from the cubical contents of the tank, using 

 the following values: 



i cubic foot of water weighs ........ 62.5 pounds 



i gallon of water weighs ........... 8.33 pounds 



i cubic foot contains .............. 7.48 gallons 



This weight is correct within one-half of one per cent, and 

 errs on the side of safety. 



Nomenclature. Fig. 18 illustrates the nomenclature of di- 

 mensions used in the formula. 



H equals the depth or head of water in feet at the point under 

 consideration. 



p equals the hydrostatic pressure in pounds per square inch, 

 hence equals 0.434^?. 



W equals the total load in pounds supported by the section 

 or member under consideration. 



Dimensions in feet are expressed by capital letters, and in 

 inches by small letters. 



Capacity of Cylinder. 



Capacity in cubic feet = 



xD 2 A 

 Capacity in gallons = ~ - - X 7 48 = 5 ID 2 A . 



Capacity in pounds X 6 2 . 5 = 49 . i D 2 A . 



For practical purposes it is accurate enough to use $oD 2 A 

 for the last expression, the error being -less than 2%, and on the 

 side of safety. 



Capacity 0} Cone. 



Capacity in cubic feet = - l = 



