220 REPOKT~1867. 



Prom the above Summary of Results may be taken almost every descrip- 

 tion of steel manufactured for the purposes of construction, when subjected to 

 a transverse strain. The utmost care has been taken to work out the con- 

 ditions and properties of the specimens ; and assuming that these conditions 

 would be fuliillcd by the manufacturer, the engineer, the architect, or the 

 builder, he could have no difficulty in selecting such material as he may 

 requii'e in the varied forms of constructions and uses for which it is in- 

 tended. 



It will be observed that in every description of manufacture, and in every 

 description of each manufacture, the whole of the transverse properties 

 have been determined, both as regards the modulus of elasticity and de- 

 flection, and the measure of work done (as indicated by the unit of working 

 strength, which will be found in the last column). The deflections up to the 

 limit of weights laid on, as also for unity of section, wiU be found in the 

 fourth and fifth columns. 



It might have been desirable to have received from the makers more ex- 

 tended information as regards the different processes of conversion, and the 

 quality of the ores, crude iron, &c. from which the specimens were obtained ; 

 these with the chemical constituents of the material would have been highly 

 valuable. But in my endeavours to arrive at correct results, much had to be 

 left to the discretion' of those who selected the samples, and to the honesty 

 of purpose by which they were guided in the selection. It is only natural 

 that the manufacturer shoidd select samples from which the best results 

 would be obtained, in order that he might in every test stand high in the 

 scale of utility. On the other hand, it must be observed that it is not the 

 material of the greatest density and strength that is required on all occasions ; 

 on the contrary, it is quite the reverse for many purposes, as in some cases it 

 is essential to have the metal soft and ductile, easily worked, and convertible 

 into shapes where its flexibihty would be important. Again, any hard 

 brittle steel capable of retaining a fine edge is of inestimable use for tools, 

 but it is totally inapplicable to structural purposes, where elasticity and 

 strength is required for endurance. All these are points which I have en- 

 deavoured to attain and simplify in the experiments, and having indicated 

 then- properties in the above Summary on Transverse Strain, we now proceed 

 to those which refer to tension. 



In submitting wrought iron or steel bars to a transverse strain, the same 

 results are not obtained as in cast iron, as bars 4 feet 6 inches long of the 

 former material will bend or deflect through a depth of some feet before 

 fracture ensues, the deflections in this case being equivalent to a permanent 

 set nearly equal to the deflection. Under these conditions, when the per- 

 manent set arrives at one-half the amount of the deflection, I have considered 

 the resisting powers of the bars so much injured as to render any additional 

 strain of no practical value. In the case of steel bars of greater density and 

 hardness, the same law between the deflection and the permanent set does 

 not exist, and hence the diiference of elasticity in the diff'erent kinds of steel 

 of which the bars are composed. To remedy these discrepancies and effect a 

 comparison between the different qualities of the material, it was necessary 

 to iix; some limitation to the weights laid on, and to ascertain the point of 

 strain corresponding to the clastic limit, — which in the calculations is that 

 point where the deflection is not in excess of what the law of deflection (viz. 

 in proportion to the strain) would indicate, whilst the next greater strain 

 gives a deflection decidedly in excess of that law. This is, however, clearly 

 explained in the abstract of results. 



