JOINTS AND CONNECTIONS 205 



It is sometimes used, in lieu of a knee brace, in order to economize 

 head room and to avoid obstructing the crane trolley travel. The 

 knuckle plate should never be used as a substitute for the knee 

 brace in a building high enough for a crane. 



The greater part of the material and all but three of the illus- 

 trations in the section on "Secondary Stresses in Framed Stresses" 

 was taken from a paper bearing that name presented by E. W. 

 Pittman before the Engineers Society of Western Pennsylvania. 

 In several paragraphs the exact language was used. The paper 

 was published in the Proceedings of the Society (Pittsburgh, Pa.) 

 for February, 1909. The student should read the whole of the 

 paper and the discussion following it. In the December, 1916, 

 issue of the Journal appeared a valuable paper by E. W. Pittman 

 entitled "Factors Affecting Cost of Structural Steel Work," and 

 a paper by George H. Danforth entitled "Some Items Affecting 

 Cost of Structural Steel Work," with discussion by a number of 

 men of wide experience. Back numbers of the Journal cost fifty 

 cents each. 



Reference was made in an earlier chapter to Smoley's Parallel 

 Tables of Logarithms and Squares, which are indispensable to 

 structural designers in computing the lengths and bevels of truss 

 and frame members. During the month of January, 1917, ap- 

 peared Smoley's Parallel Tables of Slopes and Risers, with Ready 

 Solution of Right Triangles. This second book also will be one 

 that structural designers will not willingly go without, once they 

 learn its value. 



The design of compression members will be dealt with in the 

 chapter on Columns and Structures. In Chapter VI will be 

 taken up also the design of members subjected to both tension 

 and compression. 



The "One-book Man " is not a broad man. Even with the 

 best possible explanations an author does not, always succeed in 

 getting the reader to thoroughly grasp his ideas. It is, therefore, 

 an excellent plan to do some collateral, parallel reading when 

 studying, in order to obtain the methods of working of more than 

 one person. The author believes students will receive a great deal 

 of benefit by starting at this point to study the following books. 



"Bridge and Structural Design." Thomson, $2. 



"Structural Engineering." Husband & Harby, $2.50. 



"Typical Steel Railway Bridges." Thomson, $2. 



