PROCEEDINGS OF SECTION J. (Al 
A more recent New South Wales railway specification gives 
50,000 lbs. as the required tenacity of tee and angle iron, and 
45,000 lbs. as that of plates along the grain, the contraction of 
area at point of fracture being 15 per cent. in the first, and 10 
per cent. in the second, and the elongation not less than nine or 
more than 124 per cent. on a length of eight inches. It is also 
demanded that no permanent set shall take place with 24,000 lbs. 
per square inch. Now, this is 4 reasonable specification, showing 
some knowledge of the properties and behaviour under stress of 
the material. It also takes into account, as it should, the 
difference of tenacity of bars and plates owing to the different 
mode of manufacture. In these respects it contrasts most 
favourably with those preceding. 
The South Australian Railway specifications for bridge iron 
also bear evidence of careful consideration, and of progressive 
modification with accumulating experience. That of the Terowie 
and Pichi-Richi Railway, dated 1880, requires a tenacity of 
22 tons, or 49,280 lbs., for general purpose iron, 21 tons, or 
47,040 lbs., for plates, and 22 tons, or 49,280 lbs. for angle irons 
for girder making, with 8-3 per cent. elongation, and 24 tons, or 
53,760 lbs., for rivets and bolts, with 16-7 per cent. elongation; 
while that of the Palmerston and Pine Creek Railway, dated 
1885, is still more precise, requiring 21 tons, or 47,040 lbs., with 
10 per cent. contraction for plates along the grain; 18 tons, or 
40,320 lbs., with 5 per cent. contraction for plates across the 
grain; 22 tons, or 49,280 lbs., with 15 per cent. contraction for 
angle, channel, tee and girder iron and flats over six inches 
wide ; and 24 tons, or 53,760 lbs., with 20 per cent. contraction 
for round and square iron and flats under six inches wide ; while 
for general purpose iron the requirement of the former specifica- 
tion is repeated. In both these specifications there is a list of 
names of recognised makers, from one or other of whom the 
material must be obtained. 
The most complete and elaborate specifications I have so far 
met with are those agreed upon by thirteen of the leading 
American bridge-building firms or companies, and which repre- 
sents the result of an experience of bridge-building infinitely 
‘ beyond what any other body of men can claim. They read as 
follows :— 
1. All wrought iron must be tough, ductile, fibrous, and of 
uniform quality for each class, free from cinder pockets or 
injurious flaws, buckles, blisters, or cracks. As the thickness of 
the bars approaches the maximum that the rolls will produce, the 
same perfection of finish will not be required as in the thinner 
ones. 
2. No specific process or provision of manufacture will be 
demanded, provided the material fulfils the requirements of the 
specification. 
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