Informatim respecting Rail-Roads . 10S 
]y as the manufacturing machinery will allow it, of that form 
which had been found most advantageous for cast-iron rails. 
There are two distinct parts of that form, for which it will be 
useful to have distinguishing names. The upper flat part, along 
which the wheel rolls, we may, from its analogy to the old 
wooden rails, call the tram of the rail ; to the part projecting 
downwards from this, we may apply the appropriate designa- 
tion of the keel of the rail. The keel is deepest in the middle 
between the two points, upon which the rail is supported. The 
vertical longitudinal section of the rail is therefore somewhat si- 
milar to the segment of a curve cut off by a chord. Now, as in 
the malleable rails, many such lengths are formed in one piece, 
the lower part has an undulating appearance ; and the produc- 
tion of this irregularity in depth, is one of the most ingenious 
parts of the beautiful process of their manufacture. As it is 
done by an excentric groove in one roller revolving opposite to 
a concentric one in another, it is evident that this part of the 
process cannot be repeated ; for the second attempt might mere- 
ly shift the undulations to other parts of the bar. Besides the 
undulations thus produced in the lower part, there are slighter 
corresponding ones produced in an opposite direction, in the up- 
per part of the rail. To straighten this upper surface, the rail 
is put several times through grooves in the rollers, which com- 
press that part in all directions, but exert merely a lateral pres- 
sure upon the undulated under part. Thus, if there be any dif- 
ference of texture in the different portions of the rail, the upper 
part will be more dense, and the under part will approach nearer 
to the condition of wire-drawn iron ; and each will be of the na- 
ture best suited to resist the different kinds of action to which 
they are exposed. But as the whole process takes place on a 
short mass of iron, which is gradually rolled out to about six 
times its original length, and as the operation is finished before 
the metal has lost its red heat, it is not likely that there will be 
any perceptible difference of texture, or that, in uniformity or 
toughness, the rail will be in any way inferior to other malleable 
iron. There is thus little probability of the occurrence of that 
exfoliation which it is imagined will take place upon them by 
the effect of great pressure. Not the least appearance of it is 
to be seen on rails of this sort, which have had engines of about 
