104 REPORT—1849. 
The total abrasion on 30 yards of rail we have noted at 59,170 grs. in 
four years, or 14,792°5 grs. per annum, which again is equal to 493°08 
grs. per yard per annum. This is equivalent to 00318 gr. of iron abraded 
per ton per yard, or to 1760 X‘00318=5°597 gr. per ton per mile, or 
nearly 5°6 grs. per ton per mile. 
This result corresponds closely with that of the second experiment on the 
Dublin and Kingstown line, from which we may remark, that although the 
average weight per train in this instance is only about one-half that of the 
Dublin and Kingstown line, yet that the abrasion is nearly as great, proving 
that traffic over the same rails in both directions exercises a destructive effect 
upon the molecular constitution of the iron, which is equal with trains of a 
given weight to that produced by trains of double the weight always moving 
in the one direction only, or in other words, that with equal rolling loads 
the destruction of the rails by abrasion is doubled by running the traffic in 
both directions over the same rails. Owing to the fact that the piston car- 
riage on atmospheric railways has to open the valve, there is rather more 
pressure exercised by this carriage upon the rails than is due solely to its 
weight, but this excess is so small as not to affect the question. Hence the 
excess of abrasion must be due to the motion in opposite directions con- 
tinually splitting up the topmost fibres of the iron, which have been partially 
laminated and rolled out by the former train in the contrary direction of 
motion. 
Having now arrived at the last of these prolonged experiments, we may 
combine the results into one table of the 1st and 2nd experiments on the 
Kingstown line, and of that on the Dalkey line, rejecting that on the Ulster 
as dubious, and reducing all the results to one common period of 365 days, 
or one year. 
TABLE No. 4.—Results of 1st, 2nd and 3rd Series of Experiments reduced 
to a common period of 365 days. 

First Experiment|Second Experiment|Third Experiment 
Nature a fe ated OP 57, ivedtanvaaitl OE Dabes aul. Ba Dalle Hae 

Kingst. Railway.| Kingst. Railway. way. 
grs. grs. grs. 
Abyasion in use ....| 30,725 23,843+ 14,794— 
Corrosion im use.... 7,023 2,406 + 6,113— 
Corrosion out of use . 18,436 6,562+ 8,312+ 
Difference between } 
corrosion in use 10,893 4,156 2,200 
and out of use. . if 

The preceding are the absolute losses of weight upon 30 yards of rail in 
one year. 
The following are the first differences respectively between the abrasions 
and corrosions as given in the Ist, 2nd and 3rd experiments, 2. e. differences 
between Ist and 2nd, and between 2nd and 3rd, viz.— 
Ist and 2nd. 2nd and 3rd. 
PNDYHSION:. oc cusnamterene Watsie Setituts LOSOO2 eyaaie 9049 
Corrosion in use ............ 5A 2 a ae 3707+ 
Corrosion out of use ....... wy LA 874i. seroma ae 1750+ 
These do not present a series, but we are enabled to conclude from Table 4,— 
Ist. That the abrasion by traffic on the same rails constantly decreases in 
reference to the rolling load. 

