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dams, with systems of municipal piping, with steam engines and pumping ma- 

 chinery, with locoinotives and other railway equipment, with bridges and build- 

 ings, with ships and harbor improvements — in fact, with structures and machines 

 of every conceivable type. 



The engineer is the servant of the people. His ingenuity and skill are the 

 starting point which leads to the employment of all the artisans who fill our 

 shops and factories; his work makes possible the peace and comfort of household 

 life, the success of social affairs and the perfection of business methods, and it 

 often serves to furnish inspiration for modern thought and to give direction to its 

 tendencies. 



The basis of the whole science of engineering, extensive as it is, is to be 

 found in facts which have either been deduced from practical experience or 

 derived from especially conducted experiments. The early engineer could 

 neither lean upon accepted theories nor look to precedent for guidance. It was 

 not what Brindley, and Telford, and Watt, and the two Stephensons knew, but 

 what they did, that helped to inaugurate our present era of engineering. Since 

 their day, every important structure has served a double purpose : first, that for 

 which it was especially designed, and, secondly, that which regards it as a sub- 

 ject for observation and study. Where such structures have been a complete 

 success, information concerning them has become a matter of record, and the 

 essential facts have been given a place in the annals of good engineering practice ; 

 and where structures have failed, the causes have been carefully studied, that the 

 fault might be understood and consequently avoided in future work. Successes, 

 therefore, have inspired imitators, and failures have warned all followers. 



But while it is in this manner that a large part of our present fund of engi- 

 neering data has been brought into existence, and while the process still goes on, 

 it is admitted to have its limitations. The attempt to build a house and at the 

 same time determine the subsequent behavior of certain details entering into its 

 construction, is illogical and expensive. For example, it is poor economy to 

 ascertain the strength of an iron column by finally seeing it fall under the load 

 of a wall. A crack in an arch or a fragment from an exploded boiler may testify 

 to faults in construction, and may even serve as a basis for theories leading to 

 better practice, but the information obtained is dearly paid for in the damage 

 sufJered by the collapse of the arch or the explosion of the boiler. 



Again, great as are the losses occasioned by failures, they do not equal those 

 which occur through fear of failure. The fear that workmanship may be bad or 

 materials defective leads to lavishness which could not be justified if our informa- 

 tion were more definite. It is indeed true that "factors of safety are factors of 



