Hele-Shan' & Hay. 
Phil. Trans., A., Vol. 195 , Plate 19 . 
Infinite Cylinder of Triangular Section. 
Permeability= 100. 
Infinite Cylinder of Triangular Section. 
Permeability = 100. 
31 
Hollow Square Cylinder enclosing Circular 
Solid one. Permeability = 100. 
32 
Hollow Circular Cylinder enclosing Solid 
Square one. Permeability = 100. 
