

TRANSACTIONS OF THE SECTIONS. 123 
Cost of renewal 
Cost of materials} Cost of ballast-| from decay and 
for a double line|ing per mile of | wear of materials 
for one mile,and} double line. | of permanent way 
for laying same.|_ Average. {for double line, per 
mile, per annum, 
Description of Road. 





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Cross-sleeper, timber road, and 
bridge rail, eighty pounds to the £ £ £ 
Mar scaces aged Wrasse ahaa cee teva sat 2900 800 80 
Cast-iron sleepers either for bridge 
or edge rail, Sir J. Macneill’s, or 
Mir. Batlow'ssiisas. ds) docccudd 4. dete 3260 600* 80 
Broad-flanged rail, W. H. Barlow’s} 2740 600 24 

_ It is proposed to rivet together these rails at the joint; and the paper proceeded to 
discuss the question of the feasibility of riveting together a continuous line of rails; 
directly opposite opinions have been given on this point, and amongst those opposed 
to it were Professor Barlow in 1835. ‘The matter is, the author would submit, one 
capable of being considered philosophically, and is dependent on the amount of ex- 
pansion and the strength of the iron; he showed that the contraction by cooling a 
rail through the whole of our range temperature, say 75°, would cause a tensile strain 
on the bar only equal to five tons per sectional inch, which the bar is quite capable 
of bearing. The practical fault appears to be, that the rail when riveted at alow 
temperature gives way by flexure and gets out of line, acting asa pillar, and so 
bearing, not as in tension according to its sectional area, but the cube of its width, 
and inversely as the square of the length unsupported. It would therefore appear 
perfectly safe to rivet together a line of rails, but it should be done at a high tempe- 
rature. The effect of change of temperature of the air is moreover largely reduced 
by the rail being bedded into the ballast instead of placed upon a non-conductor of 
heat like the timber sleepers. 
When the author recommended the adoption of the broad-flanged rail to the Com- 
pany for whom he tried the experiments, he did not do so on light grounds, as in 
doing so he took the responsibility of recommending a large outlay on a system 
hitherto untried except by the patentee; in now however bringing it before the Sec- 
tion, he has the concurrent opinions of a number of the most eminent of his profes- 
sional brethren. This road having been objected to for a supposed sensation of 
hardness in passing over it, diagrams of the motion of a carriage over it and other 
descriptions of road were exhibited, taken by an instrument called a salograph, and 
which appeared to show the wrought iron had less motion than any other rail. 
Tables of experiments were annexed to this paper, 

On the Calculation of Strains in Lattice Girders, with practical deductions 
therefrom. By James Barton, C.E. 
The author commenced by showing, that notwithstanding the large and valuable 
investigations of late years into the theory and forms of wrought-iron girders for large 
bridges, yet the nature, intensity, and directions of the strains in the vertical web 
or portion of the beam- which separates the top and bottom were comparatively 
neglected, or conclusions drawn without correct theory; and having shown the large 
‘amount of material used in this portion of girders, the sides in the Britannia tubes 
weighing 3454 tons, whilst the top is 2962 tons, and the bottom 2944 tons, and 
therefore the ceconomic importance of this investigation, he proceeded to explain the 
mode in which he had arrived at accurate results as to these strains in the case of 
lattice girders. He had investigated the subject, and tried some experiments on a 
* The iron roads require five or six inches less of ballast in consequence of the depth of 
wooden:sleepers, and this decreased quantity gives the same depth under the sleeper. 
