CHAP. VI. STEPHENSON'S SECOND LOCOMOTIVE. 101 



tested, and locomotives might still have been dragging 

 themselves unwieldily along at little more than five or 

 six miles an hour. 



The steam-blast had scarcely been adopted, with so 

 decided a success, when Mr. Stephenson, observing the 

 numerous defects in his engine, and profiting by the 

 experience which he had already acquired, determined 

 to construct a second engine, in which to embody his 

 improvements in their best form. Careful and cautious 

 observation of the working of his locomotive had con- 

 vinced him that the complication arising out of the 

 action of the two cylinders being combined by spur- 

 wheels would prevent its coming into practical use. 

 He accordingly directed his attention to an entire change 

 in the construction and mechanical arrangements of the 

 machine ; and in the following year, conjointly with 

 Mr. Dodds, who provided the necessary funds, he took 

 out a patent, dated the 28th of February, 1815, 1 for an 

 engine which combined in a remarkable degree the 

 essential requisites of an economical locomotive ; that is 

 to say, few parts, simplicity in their action, and direct- 

 ness in the mode by which the power was communicated 

 to the wheels supporting the engine. 



This locomotive, like the first, had two vertical 

 cylinders, which communicated directly with each pair of 

 the four wheels that supported the engine, by means 

 of a cross head and a pair of connecting rods. But, in 

 attempting to establish a direct communication between 

 the cylinders and the wheels that rolled upon the rails, 

 considerable difficulties presented themselves. The ordi- 

 nary joints could not be employed to unite the parts of 

 the engine, which was a rigid mass, with the wheels 

 rolling upon the irregular surface of the rails ; for it 

 was evident that the two rails of the line of way more 

 especially in those early days of imperfect construction 



Specification of patent, No. 3887. 



