132 IMPROVEMENT OF THE ROAD. CHAP. VJII. 



very often caused the fracture of the rails, and occasion- 

 ally threw the engine off the road. 



To remedy this imperfection, Mr. Stephenson devised 

 a new chair, with an entirely new mode of fixing 

 the rails therein. Instead of adopting the butt-joint 

 which had hitherto been used in all cast-iron rails, he 

 adopted the half -lap joint, by which means the rails 

 extended a certain distance over each other at the ends, 

 like a scarf-joint. These ends, instead of resting upon 

 _ ^ _____ the flat chair, were 



made to rest upon the 

 apex of a curve form- 

 ing the bottom of the 

 chair. The supports 

 were also extended 

 from three leet to 

 three feet nine inches or four feet apart. These rails were 

 accordingly substituted for the old cast-iron plates on the 

 Killingworth Colliery Eailway, and they were found 

 to be a very great improvement upon the previous 

 system, adding both to the efficiency of the horse-power 

 (still used on the railway) and to the smooth action of 

 the locomotive engine, but more particularly increasing 

 the efficiency of the latter. 



This improved form of the rail and chair was em- 

 bodied in a patent taken out in the joint names of 

 (Mr. Losh, of Newcastle, iron - founder, and of Mr. 

 Stephenson, bearing date the 30th of September, 1816. 

 Mr. Losh being a wealthy, enterprising iron-manufac- 

 turer, and having confidence in George Stephenson and 

 his improvements, found the money for the purpose of 

 taking out the patent, which, in those days, was a very 

 costly as well as troublesome affair. 



The specification of the same patent also described 

 various important improvements in the locomotive itself. 

 The wheels of the engine were improved, being altered 



