7 TOWERS AND TANKS FOR WATER-WORKS. 



construction, and a comparison is therefore of interest. In 

 July of the present year (1900), a large manufacturer of 

 boilers and stand-pipes writes as follows : 



' In regard to the price of steel plates, would advise 



Tank steel, under T 3 g in. at mill $1.15 



" " above ^ in. at mill i.io 



Shell steel 1.20 



Flange steel 1.25 



Fire-box steel 1.30 to 2.85 



Rivets i. 80 



In addition to the chemical and physical specifications 

 for fixing the requirements for different grades of steel, it is 

 considered good practice to stipulate certain bending and drift 

 tests, depending upon the nature of the work for which the 

 steel will be used. The Testing Laboratory, before quoted, 

 writes in this connection, " These tests frequently reject mate- 

 rial more than other requirements, as they more clearly show 

 whether the material will stand the strain for which it is 

 intended." 



The specifications for plate suggested by Prof. Pence for 

 stand-pipe material is as follows: "Material. The material 

 composing the stand-pipe shall be soft, open-hearth steel, con- 

 taining not more than 0.06$ phosphorus, and having an ulti- 

 mate tensile strength of not less than 54,000, nor more than 

 62,000, Ibs. per sq. inch; an elastic limit not less than one- 

 half the ultimate strength, an elongation of not less than 26$ 

 in 8 inches, and a reduction of area of not less than 50^ at 

 fracture, which shall be silky in character. Before or after 

 being heated to a cherry red and quenched with water at 80 

 deg. F., the steel shall admit of bending while cold, flat upon 

 itself, without sign of fracture on the outside of the bent 

 portion." 



The requirements above are the result of wide investiga- 

 tion by Prof. Pence, and plate filling these specifications 



