60 TOWERS AND TANKS FOR WATER-WORKS. 



that assurance shall be made doubly sure. It would seem that 

 if this difference is to be recognized, the acid metal should 

 alone be considered, except at a different commercial value, 

 in the choice of structural steel. It is interesting to note, 

 however, that the British Royal Navy has endorsed the fol- 

 lowing report: " With converter steel, riveted samples have 

 g'ven less average strength, greater variation in strength, and 

 much more irregularity in modes of fracture than similar sam- 

 ples of open-hearth steel. The basic open-hearth metal has 

 proven to be as good as that made on the acid hearth, and 

 after full investigation, it will be used by the Admiralty in 

 ship plates and boiler tubes on an equal footing." 



In " Manufacture and Properties of Structural Steel,'* 

 the author has this to say of the two processes of steel making : 

 " My own experience leads me to think that Bessemer steel 

 requires more work for the attainment of a proper structure 

 than open-hearth metal, so that a thick bar is more apt to 

 have a coarse crystalline fracture. This may be ascribed in 

 any particular case to improper treatment, but if it is true that 

 open-hearth metal would not be injured under a similar ex- 

 posure, then it is proven that there is a difference between 

 the metals, and if this be acknowledged, then there is no 

 necessity for further argument. 



" It is true that Bessemer metal has been used for rails, and 

 that these are exposed to great stress and shock, but it is also 

 true that a large number of rails break in service, and that the 

 use of ordinary steel rail for bridges was long ago given up as 

 dangerous. Moreover it is quite probable that the number of 

 broken rails would be considerably reduced if they were made 

 of open-hearth steel. It is acknowledged that the case is not 

 yet closed, but until the foregoing statements are controvert- 

 ed by direct and positive evidence, the only safe way for the 

 engineer is to prescribe that only open-hearth metal shall be 

 used in all structures like railroad-bridges, where the steel is 



