{ 23 ) 



Sketches of our\ Informatioji as to Rail-Roads. By the Rev. 

 James Adamson, Cupar-Fife. (Communicated by the 

 Author *). 



XSefore we can anticipate with any 'confidence the performance 

 of an engine, we must know what part of its moving power is 

 employed in the support of its own functions, independent of 

 that expended on the object of its effort. Our knowledge of tliis 

 subject is, I fear, very deficient with regard to most kinds of 

 machinery, because the sort of effect which they are employed 

 to produce, renders it difficult to estimate the power wasted up- 

 on it. It is to be hoped, that its great importance will secure 

 greater attention to it, since the comparative advantage of many 

 different forms of machinery can be determined only by the dis- 

 covery of the comparative amount of power necessary to com- 

 municate motion through them. It is not easy to devise means 

 for obtaining this object even in machinery much under our 

 controul, and we ought, therefore, to feel grateful to Mi: 

 Wood for having opened up to us some novel sources of informa-. 

 tion, likely to be productive of considerable certainty on the sub- 

 ject. The locomotive engine is a peculiarly manageable thing,, 

 since all its parts may easily be put in motion, without employ- 

 ing its ordinary moving power, and the effort required to put 

 them in motion becomes easily ascertainable. Of this advantage 

 Mr Wood has taught us to avail ourselves, and though we do 

 not find in the detail of his experiments the means of settling the 

 question completely to our satisfaction, we can anticipate import- 

 ant consequences from the prosecution of the method he has 

 pointed out. What we have chiefly to regret is, the small num- 

 ber of the experiments which are of use in this inquiry. 



It is evident, that, if the engine were allowed to descend, an 

 inclined plane, having the steam restrained from acting upon the 

 pistons, we could, from the observed time of its descent, estimate 

 the retardation by the movement of all its parts, were all put 

 in motion by the revolution of the wheels : and, besides, there are 



• We trust Mr Adamson will continue his valuable sketches : they do him 

 credit as a natural philosopher, and their style of execution is worthy of imi- 

 tation.<i*£oiT. 



