
ON RAILWAY BAR CORROSION. 95 
riment, and on my writing to Mr. John Godwin, C.E., the Engineer of the 
line, he at once acceded to my wishes, and undertook the experiment. The 
following table gives its results, which are not as satisfactory as could be 
desired, owing to some circumstances which are unexplained, and which 
induced Mr. Godwin himself to consider the experiments in that light. 
The two following letters relate to this, and show that care appears to have 
been bestowed on each step of the process. The only error I am able to 
remark is, that one-half of the rails B, intended to be exposed to corrosion 
only, were by some mistake coated to prevent corrosion ; hence in deducing 
the results of the experiments I have been obliged to double the loss on the 
three uncoated rails B, so as to get an approximation to the truth. 
“ Belfast, 8th September 1843. 
* Drar Sr1r,—I send you enclosed the result of the experiment on the 
rails which we laid down in June 1842, You will observe that they were 
taken up in June last, and I would then have sent you the particulars had 
they not appeared so unsatisfactory. I cannot account for the great difference 
in the loss of weight, for we were very careful in weighing them. The 
quality of the iron could scarcely have made the difference ; however, I send 
you the particulars, and you can draw your own conclusions. 
«B, 4, 5, 6, were coated, and of course lost nothing. 
“J am, dear Sir, sincerely yours, 
“ Robert Mallet, Esq.” “ Joun Gopwin.” 
‘ Belfast, 14th November 1844, 
“Dear S1r,—In reply to your questions relative to the account of the 
experiments on the corrosion of iron rails which I furnished you with, I beg 
to say, that the rail no¢ travelled on was the centre rail in the middle of the line ; 
they were weighed with the same beam and weights as when put down; the 
weights were properly adjusted; the beam was sensible to a quarter of an 
ounce ; the rails were weighed separately. 
“JT am very sincerely yours, 
“ Robert Mallet, Esq.” “ Joon Gopwin.” 

_ _ The direction in azimuth, in which the experimental rails were laid upon 
the Ulster Railway, was north-east and south-west, 38° 13! east of north by 
compass, as in diagram above. 

