480 EEPOET — 1886. 



lower class and less perfect workmanship for purposes to whicli they are 

 adapted ; and would thus be in the highest degree beneficial to the manu- 

 facturers' interest. 



These results can hardly be attained otherwise than by rules framed 

 upon the recommendations of a Royal Commission, who could bring to 

 their aid the experience of the inspecting officers and of the leading 

 engineers and manufacturers, and institute special experimental research 

 to elucidate any doubtful questions. Such a Commission would indeed 

 be but a revival of that of 1847, to complete the work which the former 

 Commissioners were compelled to abandon in 1849, because the applica- 

 tion of wrought iron to engineering structures was yet in its infancy, and 

 steel in its modern form unknown ; and the scope of their enquiry could 

 hardly be better defined than in the terms of the former Commission. 



The draft rules appended have been prepared to show that the views 

 above expressed are capable of taking a practical form, and to render 

 more easily apparent the advantages claimed for them. 



Abstract of Suggested Rules for the Control hy the Board of Trade of the 

 Design of Structures of Wrought Iron and Steel. 



Note. — The formula and numerical values inserted are intended 

 merely as suggestions of theories requiring further investigation for their 

 establishment, or as estimates of the values which experimental research 

 or experience would assign to the various coefficients. 



Rule 1. — Structures of wrought iron or steel to be so proportioned 

 that the calculated stress in any part due to the weight of the structure, 

 together with the moving load set at rest upon the structure, shall not 

 exceed that specified under Schedule D. Stresses due to wind alone 

 HOt to exceed 1^ times, and stresses due to the combined effect of wind 

 and load 1^ times the specified stresses. 



Rule 2. — Provision to be made for moving loads upon main girders, 

 platforms, and bracing, according to Schedules A, B, and C. 



Rule 3. — All structures to be designed to resist lateral forces, in- 

 cluding not less than 30 lbs. per square foot for wind pressure. In lofty 

 or exposed situations greater allowance to be made for wind. 



Rule 4. — Engineer to certify, both for iron and steel, that the material 

 used is, in his opinion, suitable for the purpose to which it is applied ; and 

 to supply a statement of all the tests to which it has been subjected, in- 

 cluding in all cases those required for the determination of the working 

 stress under Schedule D. 



Schedule A. 



Equivalent uniformly distributed load for designing girders of which 

 the cross section is varied, based upon the formula 



in which S=span in feet, and i{;:=load in tons per lineal foot for one track 

 estimated to produce at any point in a beam a moment of flexure equal to 

 or greater than that produced by any arrangement of the heaviest engines 

 and boiler trucks. 



