CHAP. XIV. THE CARRYING STOCK. 283 



all these contrivances, Mr. Stephenson's inventiveness 

 was kept constantly on the stretch ; and though many 

 improvements in detail have been effected since his 

 time, the foundations were then laid by him of the 

 present system of conducting railway traffic. As a 

 curious illustration of the inventive ingenuity which he 

 displayed in contriving the working of the Liverpool 

 line, we may mention his invention of the Self-acting 

 Brake. He early entertained the idea that the momen- 

 tum of the running train might itself be made available 

 for the purpose of checking its speed. He proposed to 

 fit each carriage with a brake which should be called 

 into action immediately on the locomotive at the head of 

 the train being pulled up. The impetus of the carriages 

 carrying them forward, the buffer-springs would be 

 driven home, and, at the same time, by a simple 

 arrangement of the mechanism, the brakes would be 

 called into simultaneous action ; thus the wheels would 

 be brought into a state of sledge, and the train speedily 

 stopped. This plan was adopted by Mr. Stephenson 

 before he left the Liverpool and Manchester Eailway, 

 though it was afterwards discontinued ; and it is a A 

 remarkable fact, that this identical plan, with the addi- 

 tion of a centrifugal apparatus, has quite recently been 

 revived by M. Gruerin, a French engineer, and exten- 

 sively employed on foreign railways, as the best method 

 of stopping railway trains in the most efficient manner 

 and in the shortest time. 



Finally, Mr. Stephenson had to attend to the improve- 

 ment of the power and speed of the locomotive always 

 the grand object of his study, with a view to economy 

 as well as regularity in the working of the railway. In 

 the " Planet " engine, delivered upon the line immediately/ 

 subsequent to the public opening, all the improvements 

 which had up to this time been contrived by him and 

 his son were introduced in combination the blast-pipe, 

 the tubular boiler, horizontal cylinders inside the smoke- 



