230 IVORY AND THE ELEPHANT 



square inch. A notable property of ivory was its rapid 

 recovery from a state of strain resulting from loads con- 

 siderably above the elastic limit of the material. 



TABLE I 



MATERIAL ELASTIC LIMIT 



Tensile Tests 



Hard Ivory 9,500 



Soft Ivory 8,000 



Compression Test 

 Ivory, quality not stated 13,000 



ULTIMATE 



MODULUS OF 



RESISTANCE 



ELASTICITY 



22,130 



2,410,000 



22,010 



1,975,000 



24,890 



1,820,000 



That a comparison may be made between the results ob- 

 tained from the above tests and other well-known mate- 

 rials. Table II has been compiled. A range of values have 

 been given in some instances, representing the upper and 

 lower limits of strength which might be expected from ma- 

 terials listed. 



TABLE II 



TABLE OF RESISTANCES TO TENSILE AND COMPRESSIVE STRESSES AND 

 MODULI OF ELASTICITY OF VARIOUS MATERIALS 



„ COMPRESSIVE 



ELASTIC LIMIT TENSILE STRENGTH „ „ ^ „„ MODULUS OP 



MATERIAL STRENGTH LBS. 



LBS. PER SQ. IN. LBS. PER SQ. IN. „^„ ^^ ^^^ ELASTICITY 



Brick . . . No definite 3 to 10 thousand 0.5 to 3 millon 



Iron and Steel 



Cast Iron . No definite 15 to 35 thousand 60 to 80 " 8 to 15 " 



Wrought iron 30 to 35 40 to 50 " 50 to 60 " 28 " 



Miid Steel . 40 to 45 55 to 60 " 50 to 60 " 30 " 

 High Carbon 



Steel . . 45 to 55 70 to 80 " 80 to 110 " 30 " 



Stone 



Granite 15 to 35 " 2 to 9 " 



Jade 5 to 6 " 41 to 95 " 3 to 47 " 



Limestone 7 to 20 " 3 to 5 " 



Sandstone 5 to 15 " 1 to 5 " 



Wood 



Long Leaf Pine 50% of Ten. Str. 12 " 8 " 1 to 2.5 " 



Spruce . . " " " " 8 " 6 " 1 to 1.5 " 



Oak . . . " " " " 10 " 7 " 1 to 2.5 " 



