[bowman] fundamental PROCESSES IN HISTORICAL SCIENCE 587 



still be, as it is now, the principles, purpose and ability which are mani- 

 festly shown by his narrative and together exemplify as a whole the 

 requisites of trustworthiness to a degree not found in any other 

 historian. He anticipated what proved to be actually the case, 

 that in the ordinary course of things the sources of his information 

 must soon be forever gone, and instead of vainly citing them, he 

 so used them that his record should stand in their place as a "posses- 

 sion forever;" thereby "preserving from decay the memory of what 

 men had done." 



NOTE. 

 Page 504, lines 11, 22. 



The adopted span of the Quebec bridge was 1,800 feet. Of the great cantilever 

 bridges in America, the Monogahela, erected in 1902-1903, has a span of 812 feet; 

 and the Blackwell's Island bridge, erected in 1901-1908, has a span of 1,182 feet. 

 The design and construction of the Blackwell's Island bridge were contemporaneous 

 with that at Quebec, and the Quebec designers had not access to the Blackwell's 

 Island plans. 



The Forth Bridge in Scotland, erected 1882-1889, has a span of 1,710 feet. 

 This bridge is in a class by itself, and was built on a system not suited to the es- 

 tablished American methods. The system followed in its construction is very 

 expensive, and much excessive weight could be put into a bridge of the American 

 type with a cheaper total cost than that of the Forth bridge. The stress sheets and 

 full engineering studies in connection with this bridge have not been published. No 

 criticism touching the practical success of the design has ever been made, but it is 

 not a class of construction that could be adopted by an American bridge company 

 without making material changes in its shop equipment and methods of handling 

 its business; so that the distinctive features of design, construction and erection of 

 this Scottish bridge were not followed at Quebec. 



