SCHUYLKILL PERMANENT BRIDGE. 35^ 



Thejra?ne is a masterly piece of workmanship; com- 

 bining in its principles, that of /ci?tg posts and bracesj 

 or trusses, with those of a stone arch. Half of each post 

 with the brace between them, will form the vousseur of 

 an arch ; and lines through the middle of each post, 

 would describe the radii or joints. There are three 

 sections of the frame, all similar. That in the middle, 

 divides the space into two equal parts, so that passen- 

 gers in opposite directions, are prevented from inter- 

 fering with each other. 



The platform for travelling rises only eight feet from 

 an horizontal line, and the top, or cap pieces, are paral- 

 lel to this. Of the sections, the middle one has the 

 most pressure, owing to the weight of transportation, 

 being thrown nearer to that section than towards the 

 sides ; to which the foot ways prevent its approach. 

 These foot ways are five feet in width, elevated above the 

 carriage ways, and neatly protected with turned posts 

 and chains. It has been conceived that the foot ways 

 would have been more advantageously placed on each 

 side the middle section, to throw the weight of trans- 

 portation to the sides of the bridge. 



Mr. Palmer (who is believed to be the original in- 

 ventor of this ki?id of wooden bridges) permitted with 

 much candour, considerable alterations in this plan, ac- 

 commodatory to the intended cover, the design where- 

 of is original. These were so much approved by him, 

 that he considers the Schuylkill bridge superstructure 

 the most perfect of any he has built. It was finished 

 in one season ; and declared open for passengers and 

 transportation, on the first day of January, 1805. 



