IRON AND STEEL. 83 



larged use of iron and steel, which has resulted from 

 these improvements in its make, has led to the adoption 

 of mechanical means to supersede hand labour in almost 

 every branch of trade and agriculture, by which the 

 power of production has been increased a hundredfold, 

 while at the same time much higher precision has been 

 obtained. Sir Joseph Whit worth has done more than 

 any one else to perfect the machinery of this country 

 by the continued efforts he has made, during nearly 

 half-a-century, to introduce accuracy into the standards 

 of measurement in use in workshops. He tells us 

 that when he first established his works, no two articles 

 could be made accurately alike or with interchangeable 

 parts. He devised a measuring apparatus, by which 

 his workmen in making standard gauges are accustomed 

 to take measurements to the 2 oooo of an inch. 



In its more immediate relation to the objects of 

 this Association, the increased importance of iron and 

 steel has led to numerous scientific investigations into 

 its mechanical properties and into the laws which 

 govern its strength ; into the proper distribution of the 

 material in construction ; and into the conditions which 

 govern the friction and adhesion of surfaces. The 

 names of Eaton Hodgkinson, Fairbairn, Barlow, Rennie, 

 Scott Russell, Willis, Fleeming Jenkin, and Galton are 

 prominently associated with these inquiries. 



The introduction of iron has, moreover, had a vast 

 influence on the works of both the civil and military 

 engineer. Before 1830, Telford had constructed an 

 iron suspension turnpike-road bridge of 560 feet over 

 the Menai Straits ; but this bridge was not adapted to 

 the heavy weights of locomotive engines. At the 



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