ABBREVIATIONS EMPLOYED. 139 



inch usual in England it is necessary to divide them by 151-1. 

 (See footnote on p. 133 ) 



So too while Professor Thurston defines the modulus of rupture 

 as "the quantity which represents the stress upon a unit of area 

 of cross-section ... at the instant of breaking under the trans 

 verse stress," and Mr. Sharpies expresses this breaking-weight, as it 

 is generally termed, in kilograms per square centimetre, English 

 writers here also use tons or pounds per square inch. So 

 too Mr. Sharpies gives the resistance to longitudinal presssure, or 

 ultimate weight which a stick will support, in the number of 

 kilograms required to crush a stick one centimetre square by 

 such pressure, while Mr. Laslett terms this, vertical strength, and 

 states it in the number of pounds of vertical force required to 

 crush 1 square inch of base. Mr. Sharpies also gives the resistance 

 to indentation or number of kilograms required to sink a punch one 

 centimetre square to the depth of T27 millimetres perpendicularly 

 to the fibres. 



It is well nigh impossible to reduce all the results of different 

 experimenters. They will, therefore, be here stated mainly 

 in the form and with the terminology of their respective 

 authors. 



The following symbols will be employed : 



S.G. = Specific gravity, compared to water as 1000. 



W = Weight of a cubic foot in pounds. 



E = Co-efficient of elasticity, stated in tons or pounds per square 

 inch, or in kilograms per square centimetre. 



e' = Elasticity compared to Oak as 1 '00. 



p Transverse strength in pounds per square inch. 



p' = Transverse strength compared to Oak as 1 '00. 



/= Co-efficient of bending strength in tons per square inch. 



ft = Tensile strength or tenacity along the fibre, in tons per 

 square inch. 



c = Direct cohesion, in pounds per square inch. 



c = Cohesion compared with Oak as 1 -00. 



fc = Crushing strength along the fibre, in tons per square 

 inch. 



