DESIGNING. 



I 9 7 



proportioning the section so that the unit stress will be proper 

 and reasonable. On page 105 column formulas are discussed 

 and tables are given for the investigation and design of columns 

 and struts, while, as has been stated, most of the manufacturers' 

 lists furnish correct tabulation of the elements of the standard 

 shapes. 



GENERAL DETAILS. 



Tank-cover. Small water-towers are generally open at the 

 top and are provided with a circumscribing angle, usually sur- 

 mounted by a malleable iron cresting of ornamental design, 

 but with tanks of capacities as large as say 50,000 gallons. The 



FIG. 54. 



practice is to provide some sort of cover, the simplest, and prob- 

 ably the best, being a light steel-plate roof, projecting over the 

 cylinder and terminating with a light circular eaves-angle, forming 

 a conical cover. This design may be elaborated by extending 

 the eaves-angle, back of which may be riveted to a bent plate 

 a steel facia plate as shown in Figs. 54-55, or omiting the lat- 



