CAMBEIA STEEL. 403 



WOODEN BEAMS AND COLUMNS. 



The results of a series of studies of wooden beams and columns 

 of various kinds of American timber are contained in the Pro- 

 ceedings of the Fifth Annual Convention of the Association of 

 Railway Superintendents of Bridges and Buildings, October, 1895, 

 at which the Committee on Strength of Bridge and Trestle 

 Timbers presented a report, portions of which have been used in 

 preparing certain of the tables on the following pages, but as 

 noted thereon the arrangement and values in many cases have 

 been modified by later information from various sources. 



The publications of the Forestry Division of the United States 

 Department of Agriculture, Bulletins Nos. 8 and 12, and Circular 

 No. 15, contain reports of tests of American woods, and deduc- 

 tions drawn therefrom. Extracts and tables from these reports 

 are given on the following pages. 



The tables of safe loads for wooden beams and tables of 

 strength of wooden columns given on the following pages have 

 been specially calculated for this book, Using the information 

 regarding the properties of the various species contained in the 

 reports above referred to, as modified in some cases by later data. 



In order that information on this subject will be more complete, 

 tables are given herein showing structural timber stress values, as 

 published in the United States Forestry Service Bulletin, No. 108, 

 and also those recommended by the American Railway Engineer- 

 ing and Maintenance of Way Association, Bulletin No. 107. 



Explanation of the Tables of Safe Loads in Pounds, Uni- 

 formly Distributed, for Rectangular Wooden Beams 

 One Inch Thick, Pages 416 to 421 Inclusive. 



General. 



For convenience in use, three of these tables have been prepared 

 from which the safe loads of the various species can be obtained, 

 either directly or by proportion as stated in the footnotes. 



The values given in the tables are the safe loads in pounds uni- 

 formly distributed, including the weight of the beam itself, for 

 rectangular beams one inch thick for spans from four to forty feet 

 and for depths from four to twenty-four inches. The safe load 

 for a beam of any thickness may be found by multiplying the 

 values given in the tables by the thickness of the beam in inches. 



The last column of each of the three Tables of Safe Loads for 



