44 



MR. W. FAIRBAIRN ON THE 



the tubes upon horizontal and transverse beams of great 

 strength, and by increasing the area subject to compression, 

 the splitting or crushing of the masonry might be prevented. 

 This was done with great care, and the result is the present 

 stability of those important structures. 



In conclusion, I have now to submit to the consideration of 

 the society and the practical builder the following general 

 summary of results, obtained from various materials, showing 

 their respective powers of resistance to forces tending to crush 

 them. 



GENERAL SUMMARY OF RESULTS ON COMPRESSION. 



Crushing force 

 Description of Material. in lbs. Authority. 



per square inch. 



/ Cast steel 



Blister steel 



Iron \ Cast iron (white, derived ] 214816 \ Fairbaim's Experi- 



arid < from 14 meltings) .... j j ments on the Mechani- 



Steel. I Ditto (from 12 meltings). . 163744 \ cal Properties of Metals. 



t-v... >/, ]. ° i > I — .Transactions of the 



Ditto (from ordinary cast- ] g96()() \ British Association, 



ings) j / 1854. 



Porphyry 40416 Gauthey. 



Grauwacke, Penmaenmawr 16893 Exprmts. No. 12. 



Granite, mean of 3 11565 Do. Nos. 14,18,19. 



Sandstone, Yorkshire .... 6127 Rennie. 



Ditto, mean of 9 exprts. . 9824 Exprmts. 1 to 10. 



/ Ditto, Runcorn 2185 Clark. 



^ Limestone 8528 Exprmts. 21, 22. 



Ditto, Anglesey 7579 Clark. 



Ditto, Magnesian — mean. . 5074 Exprmts. 23, 24. 



Brick, hard 1888 Rennie. 



Ditto, red 805 „ 



Ditto, mean of 4 exprts. . . 1424 Clark. 



(Box 9771 



English Oak (dried) 9509 



Ash (ditto) 9363 



Plumtree (ditto) 8241 v 



> Beech 6402 > Hodgkinson. 



/ Red Deal 5748 



Cedar 5674 



\ Yellow Pine 5375 



