DEVELOPMENT OF THE AMKRICAN RAIL AND TRACK. 



661 



sleepers. The wedge form is used because the strength of a rail is 

 always proportioned to the square of its breadth and depth. Hence 

 this (wedge) form of rail possesses all the strength of a cube equal to 

 its square. The joints are made with a pin." Birkeushaw showed 

 great ingenuity in designing the rolls by which these rails were fairly 

 rolled in lengths of 18 feet. Cast bars were soon after dispensed with. 

 The model is made from drawings and specifications, English patent 

 No. 450.3, to John Birkeushaw, sealed October 23, 1820. 



Fig. 33, wrought-iron edge rail with fish-bellied web. These rails 

 were used by Stephenson in 1S29 in laying the Liverpool and Man- 



S£ETMW'CH/UR. 



Fig. 33. 

 Fish-Belly Rail, Designed by George Stephenson am> laid on the Manchester and Liver- 

 pool Railway. (1829.) 



From model m the I - . S. National Museum.) 



Chester Railway. Chairs used at joints; rails 15 feet long; supports 3 

 feet apart; weighed 35 pounds per yard. 



Fig. 34 shows a cross section of the original rail laid on the old Port- 

 age Railroad over the Allegheny Mountains in Pennsylvania. These 



Fig. 34. 



ENGLI3H Rolled Kail, Clarence Pattern, laid on the old 



Postage Railway ok Pennsylvania, 1833. 



I ram original in the r. s. National Museum. 



rails were imported from England in 1832 and laid in 1833. A section 

 of this rail is in the collection. A portion of the New Jersey Railroad 

 (from Jersey City to New Brunswick) was also laid with T rails of the 

 fish-belly pattern, similar to Fig. 33. 



