

Figure 2i. Im Harpers Ferri bridgi toward the end of its career, carrying a common 

 road ovei the P ai I he westernmost line ol trussing and span no. i had been re- 

 moved long before. View through the Winchestei span looking toward Maryland in 

 P H ■• Ferry National Historical Pc 



standing flanges for riveting together. The circular 

 sei nun is theoretically the mosl efficient to bear 

 compressive Loading. A column of any required 

 diameter could be produced by simply increasing the 

 number of segments, the individual size of which 

 never exceeded contemporary rolling mill capacity 

 (see fig. 16). 



The design exhibits the inspired combination of 

 function. il perfection and simplicity thai seems to 

 ( haracterize most great inventions. 



It may have been because he had no facilities for 

 rolling that Bollman communicated his idea to 

 Reeves, although this seems illogical. At am rate, 

 Reeves and his associates patented the system exten- 

 sively, .nul the Phoenix column was eventually 

 employed to the virtual exclusion of cast-iron and 

 other types of wrought-iron columns. H\ the end of 



the 1 'ih century it began to pass from use, as mills 

 became capable of producing larger sections with 

 I H i iperties relatively favorable to column use and more 

 adaptable to connection with other members. 



Final Use oi the Bollman Truss 



The Bollman truss found occasional use elsewhere 

 than on the B. & O. lines, but generally only when 

 erected on contract by Patapsco Bridge and Iron 

 Works. However, the fact t li.it Bollman could prof- 

 it. iN\ ereel this bridge in the severely competitive 

 I870's indicates that the harsh criticism of the system 

 by authorities of such stature as Whipple was not 

 necessarily justified. Bollmai i ements, in 



fact, refer to the favorable recommendations of other 



l'AI'IR 36: ENGINEERING t:n\ I RIB! 1 IONS < IF WENDEL HOI I \l \\ 



95 



