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272 WILLIAM FIELD HOW. 
and that the elongation was less when it was taken in two inches 
than in the longer bars. These results surprised the author until 
it was explained to him that very short lengths of fair diameter, 
such as the samples referred to, invariably give higher tensile 
results than is the case with longer test pieces from the same 
material. ‘This is considered to be due to the close adjacent sides 
supporting the metal in the short samples, and it has been found 
that if holes be drilled in a straight line across a plate, the metal 
of which has a certain tensile strength, the strength of the plate 
across the holes is not reduced in proportion to the sectional area 
removed, but, owing to the fact referred to, is about ten per cent. 
greater. 
Owing to the circular form of tyres, it is not, in many cases, 
possible to machine pieces out of them that would permit of a 
greater length than two inches being under tension, and as the 
test specimens are usually -25 inch in area, the high tensile 
strength and low elongation recorded are no doubt different to 
that which would be obtained if longer lengths were possible, and 
one would naturally think this would be the case from the manner 
in which such tyres bend and stand shocks under the falling 
weight tests. 
As the tensile and bending qualities of iron and steel have a 
distinct relation to each other, engineers who have had practical 
experience in the testing and examination of material, can obtain 
a fairly good idea from the behaviour of the iron and steel when 
bent and from the appearance of the fracture, if it is likely to 
stand the specified tensile tests. Such bending tests afford a 
ready means of judging, at the site of delivery, if material 
supplied is equal to that ordered and suitable for the purpose 
intended. Bending tests should not be carried out by people 
inexperienced in the proper treatment of iron and mild steel. Such 
persons, through unreasonable treatment and faulty preparation . 
of specimens, cause the material to break when bent through very 
stnall angles; and again, it is possible by sharp and repeated 
blows to cause iron to break with a crystalline fracture, whereas, 
