896 REPORT—1896. 
The following Papers were read :— 
1. Physical and Engineering Features of the River Mersey and the 
Port of Liverpool. 
This Paper was ordered by the General Committee to be printed zz extenso.— 
See Reports, p. 548. 
2. The Cause of Fracture of Railway Rails. 
By W. Worsy Beaumont, I Jnst.C.£. 
In this paper the author gives an explanation of the apparently anomalous 
fractures of railway rails. Attention is first directed to the leading features in the 
history and characteristics of fractured rails, and from these the conclusion is drawn 
that the failure of any rail, however perfect, is chiefly a question of the number 
and weight of the trains passing over it. The effect of the rolling of the heavily 
loaded wheels of engines and vehicles! is the gradual compression of the upper part 
of the rails and the production thereby of internal stresses which are cumulative 
and reach great magnitude. That which takes place in the material of a rail head 
under the action of very heavy rolling loads at high speed, is precisely that which 
is purposely brought into use every day in our ironworks. The effect is, however, 
obscured by the slowness of the growth and transmission of the forces which are 
ultimately destructive. 
When a piece of iron or steel is subjected to pressures exceeding the limit of 
elastic compression, by a rolling or hammering action, or by both these combined, 
the result is spreading of the material and general change of the dimensions. This 
is equally the case with a plate pane hammered on one side or rolled on one side 
while resting on a flat surface, or with a rivet when hammered over. In all these 
cases and many others, the hammering or rolling work done upon the surfaces 
tends to compress the material beneath it, but being nearly incompressible and 
unchangeable in density, the material flows, and change of form results. 
Generally the material thus changed in form suffers permanently no greater 
stresses than those within its elastic limit of compression or extension. When, 
however, the material is not free to flow or to change its form in the directions 
in which the stresses set up would act, the effect of continued work done on the 
surface is the growth of compressive stress exceeding elastic resistance. 
In the case of railway rails the freedom for the flow of the material is very 
limited, especially when considered with reference to the rolling and hammering 
media and the surface contact between rails and wheels. Hardening of the surface 
takes place and destructive compression of the surface material is set up, If the 
material be cast iron, the destructive compression causes crumbling of the superficial 
parte and the consequent relief of the material immediately below it from stress 
eyond that of elastic compression ; but when the material is that of steel rails, 
the stress accumulates, the upper part near the surface being under intense 
compression, differentiating from a maximum at the surface. 
This compression gives rise to molecular stresses analogous to those which, 
on the compression side or inner curve of a bar bent on itself, originate traverse 
flaws on that side. 
This condition of compression exists along the whole length of a rail, so that 
when its magnitude is sufficient to originate crumbling or minute flaws, any 
unusual impact stress, or a stress in the direction opposite to that brought about 
by the usual rolling load, the rail may break into two or into numerous pieces. 
Stresses originating in the same manner explain the fracture of railway tyres as 
described fully by the author in the ‘ Proceedings of the Institution of Civil 
Engineers,’ 1876, vol. xlvii. 
1 The static pressure per square inch of surface contact between wheel and rail 
with locomotive weights now common is considerably more than 30 tons, and the 
pressure under heavily balance-weighted locomotive wheels at high speed is much 
greater than this. 
