6 



May 12, 1859. 



Sir BENJAMIN C. BRODIE, Bart., President, in the Chair. 

 The following communications were read : 



I. "On the Resistance of Glass Globes and Cylinders to collapse 

 from external pressure, and on the Tensile and Compressive 

 Strength of various kinds of Glass." By WILLIAM FAIR- 

 BAIRN, Esq., C.E., F.R.S., and T. TATB, Esq., F.R.A.S. 

 Received May 3, 1859. 



(Abstract.) 



The researches contained in this paper are in continuation of those 

 upon the Resistance of Wrought-Iron Tubes to collapse, which 

 have been published in the 'Philosophical Transactions 5 for 1858. 

 The results arrived at in those experiments were so important as 

 to suggest further inquiry under the same conditions of rupture 

 with other materials ; and glass was selected, not only as differing 

 widely in its physical properties from wrought iron, and hence well 

 fitted to extend our knowledge of the laws of collapse, but because 

 our acquaintance with its strength in the various forms in which it 

 is employed in the arts and in scientific research is very limited. 

 To arrive at satisfactory conclusions, the experiments on this mate- 

 rial were extended so as to embrace the direct tenacity, the resist- 

 ance to compression, and the resistance to bursting, as well as the 

 resistance to collapse. 



The glass experimented upon was of three kinds : 



Specific gravity. 



Best flint-glass 3-0782 



Common green glass. . . . 2-5284 



Extra white crown-glass 2*4504 



Tenacity of Glass. For reasons detailed by the authors, the ex- 

 periments upon the direct tenacity of glass made by tearing speci- 

 mens asunder are less satisfactory than those in the rest of the 

 paper ; and it is argued that more reliance is to be placed upon the 

 tenacity deduced from the experiments on the resistance of globes 

 to bursting in which water-pressure was employed, than upon the 

 tenacity obtained directly by tearing specimens asunder. The 



