549 



pounds to the yard. It is found in the Liverpool and 

 Manchester rail-road, that the very rapid succession of 

 heavy carriages produces in consequence of a vibration, 

 a much more destructive effect upon the rails than was 

 anticipated. It is a singular fact, that the rolling motion 

 upon the wrought iron rail prevents oxydation or rust. 

 In Massachusetts it is proposed to substitute a running 

 stone foundation of perfectly even surface, on which a thin 

 rolled iron plate is to be laid about two and a half inches 

 wide and half an. inch thick; this plate is to be bolted 

 down to the stone. The elasticity of this, being less 

 than that of wood, renders it preferable, and the plan has 

 already been partially adopted with success. The expe- 

 rience, however, at Manchester may suggest the proprie- 

 ty of greater thickness in the iron plate. To overcome 

 the frost, so great an obstacle in our country to works of 





this description, it is proposed to lay deep foundations for 

 the stone rail. 



In a railway, the first principles are to form it through- 

 out its whole length, as nearly upon a level and in as di- 

 rect a line as circumstances will permit . This is obvious, 

 for an acclivity for one hundred feet on a road of one 

 hundred miles, would prevent a load over the whole ex- 

 tent greater than that limited by the ascent itself, unless 

 at the cost of unloading or of extra power. This uni- 

 form level or gentle inclination is attained by deep cut- 

 tings through hills, by long embankments in the valleys, 

 and by bridges over deep gullies and streams. 



The width required for a public and double railway 

 for extensive traffic, is seldom over twenty feet, and for 

 a single track twelve feet, far less than that required for 

 ordinary canals. The horse track is generally in the 

 middle. 



It is found that an ascent of twentysix feet in the mile 

 makes no perceptible inconvenience in the railway, and 

 that anything less than sixty or eighty feet produces but 

 slight difficulty. In a canal on the contrary, four inches 

 in the mile is the greatest allowance that can be made, 

 even in feeding sections, absolute level being the rule. 

 The Mississippi, at New Orleans even during the freshet 

 falls but one and a half inches each mile. When it is 



VOL. i. NO. XXIH, 49* 



