TRANSACTIONS OF SECTION G. 



873- 



railway working.', or otlierwise interested in the matter, as to tlie origin of the 

 specimens. Tlie prevalent opinion seems to be that they were torn from the tyres 

 of skidding wheels, rather than from the rails upon which they skidded during the 

 descent of trains upon inclines. Mr. Routledge, however, having regard to the 

 evidence of the analyses, is of opinion that they have come from the ?y//&, and not 

 from the tyres. It appears that the steel of which the tyres analysed were com- 

 posed differs from that of which the rails were made by higher silicon and lower 

 manganese, which is not the case with the specimens. The presence of tin in the 

 latter is somewliat remarkable, but that element has sometimes been found in pig 



The author thinks, however, that inasmuch as blows, or charges, of sceel are 

 often run indiscriminately into ingots for rails or for tyres, and as it cannot be 

 stated certainly what was the composition of the idenf^ical tyres and rails con- 

 cerned in forming the specimens analysed, it is scarcely prudent to found any 

 strong argument upon these analyses. 



The practical lesson taught by the specimens is that wheels should never be 

 skidded. But, on the other hand, Trains, whether passenger, goods, or mineral,, 

 should always beretarded by braking a sulEcient number of wheels to effect the 

 desired object, with a pressure somewhat short of skidding. Skidding wheels is 

 indeed a barbarous and ineffectual attempt at retardation, whilst it is a most 

 eflectual cause of disintegration. 



The specimens looked at from a scientific point of view are mteresting. Their 

 colour indicates that they have been formed at a high temperature, as they have 

 clearly all beep originally coated with magnetic oxide (Fe.,pj. The comparatively 

 large body of metal forming the rail and its continual presentation of new surfaces 

 during skidding make it improbable that it could have reached any high tempera- 

 ture : whereas skidded wheels might easily present the same surface long enough 

 to accumulate heat locally to a greater extent than could be, pciripasm, dissipated 

 by conduction. The multitude of folds which appear in all the specimens, and the 

 tendency to spread into various forms, seem to indicate that under the pressure to 

 which they have been subjected the metal has ' flowed ' with great freedom. 



Reviewing the evidence obtained so far, the author inclines to accept the 

 following conclusions, viz. : — 



1. That the pieces have come from the ti/7-es of skidding wheels, and not from 

 the rails. 



2. That they were produced at a sufficiently high temperature for the formation 

 of magnetic oxide, i.e., at a 7'ed heat. 



?,. That they were forced out from heUnd the skidding wheels (the folds being 

 on the under side) until from their accumulated length and weight they fell off. 



4. That the only way to avoid the destructive action which they indicate is to 

 brake more wheels to an extent short of skiddinc. 



