ss REPORT—1849. 
Report on the Experimental Inquiry conducted at the request of the 
British Association, on Railway Bar Corrosion. 
By Rosert Macuet, M.R.LA., Mem. Inst. C.E. 
Ir having been long loosely rumoured that railway bars corrode less when 
in use, i. e. travelled over, than when out of use, and the only evidence for this 
being that they appear to do so to the eye, and several vague speculations 
having been broached by engineers and others to account for the assumed 
facts, it seemed desirable to ascertain the truth experimentally, and also to 
determine at the same time the constants of abrasion by the action of the 
wheels of railway carriages, this latter being in fact a necessary prior question 
to the research as to corrosion. 
A general sketch of the views promulgated on this subject is contained in 
my Third Report on Corrosion of Iron to the British Association in 1843; a 
sum of £20 having been placed at my disposal by the British Association at 
the Manchester Meeting in 1842, for the purpose of these experiments. 
The first experiments were directed to the object of ascertaining the fuct 
of any difference in the amount of corrosion by air and water, &c. between 
railway bars in use and out of use, in an exact and unexceptionable manner ; 
and from the great weight of the rails requiring a balance of great strength, 
this was found by no means an easy matter, as the difference of corrosion in 
any moderate time might be expected not very greatly to exceed the errors 
of weighing. The first sets of experiments arranged were on the Dublin 
and Kingstown Railway, upon that part of the line which lies near Sydney Pa- 
rade, at the Dublin side of the level crossing there. 
The line is quite straight, the brakes are never applied here, and the rails 
are level. Three sets of six lengths of fifteen feet rails each, were here laid 
down upon the coming into town or western line. 
The direction by compass of the rails at this point is north-west and south- 
east, and hence these rails were always traversed over in a direction from 
south-east to north-west. 
The experimental rails were laid in the following way :—Having been care- 
fully weighed, viz. two sets of bars of six each were laid into the coming-in line, 
and secured in the same way as all the others on the line, by cast-iron chairs 
and compressed wood wedges resting upon longitudinal memel sleepers, and 
with pine or memel filling-pieces between the chairs, filling up the spaces be- 
tween the bottoms of the rails and the tops of the sleepers. 
Of these two sets laid into the line, one set of six bars (No. 2 marked **) 
was exposed freely and without any preparation, and was placed on the eastern 
side of the coming-in line; the other of the two sets (No. 3 marked **+) was 
coated: ail over with boiled coal-tar, laid on the iron when hot, so as to 
protect it from all corrosion. The third set of (6) bars (marked No. 1 *) was 
laid upon wood sleepers, chairs, &c., in the same way as the others, but were 
placed aside by themselves in the middle of the road between the two lines 
of railway, without any preparation, and freely exposed to corrosion, but not 
travelled over. 
All three setsof bars before being laid down or coated were heated in a boiler- 
maker's oven to a bright red heat, to remove all rust bya scale, leave their sur- 
faces perfectly uniform and alike, and were permitted to cool slowly without 
any blows, and ina horizontal position, so as to have as little permanent mag- 
netism as possible. 
Thus arranged the three sets of bars stood upon the line in the following 
order : 

4 
bi 
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