220 ELEMENTS OF ELECTRICAL ENGINEERING. 



Rules * with the object of minimizing fire risks and risks of per- 

 sonal injury. These rules are published in convenient form and 

 at a nominal price by the National Board of Fire Underwriters f 

 under the title " The National Electrical Code," and a supple- 

 ment, which is revised semi-annually, contains a list of all kinds 

 of electrical wires and fittings which are approved by the Under- 

 writers. Any person who assumes any degree of responsibility 

 for "the laying out, or even the maintenance, of electrical installa- 

 tions should be familiar with the National Electrical Code. 



The rules and requirements which constitute the National 

 Electrical Code are classified in the edition of 1905 as follows : 



Class A. Rules applying to stations and dynamo rooms. 



Class B. Rules applying to outside work. 



Class C. Rules applying to inside work. 



Class D. Rules applying to fittings, materials, and details of 

 construction. 



Class E. Miscellaneous rules. 



Class F. Rules applying to marine work. 



97, Installation and operation costs. From one point of view 

 engineering is a composite of all the physical sciences, and from 

 another point of view it is a branch of the science of economics. 

 Any elementary treatise on engineering must, however, be chiefly 

 devoted to purely physical problems inasmuch as the student 

 must become familiar with engineering as a branch of physical 

 science before he can possibly undertake as a practicing engineer 

 to choose that particular physical solution of an engineering prob- 

 lem which will best meet the requirements of economy. 



*The following is a list of the Associations composing this National Conference : 

 American Institute of Architects, American Institute of Electrical Engineers, Amer- 

 ican Society of Mechanical Engineers, American Institute of Mining Engineers, 

 American Street Railway Association, Associated Factory Mutual Fire Insurance 

 Companies, Association of Edison Illuminating Companies, International Association 

 of Fire Engineers, International Association of Municipal Electricians, National 

 Board of Fire Underwriters, National Electric Light Association, National Electrical 

 Contractors' Association, Underwriters' National Electric Association. 



f General Agency 34 Nassau St., New York City. 



