242 APPLIED SCIENCE 



AVERAGE TENSILE STRENGTH OF MATERIALS IN POUNDS PER 

 SQUARE INCH Continued 



'Iron: Cast: 18000 Silver: Cast 40000 



Lunkenheimer 25000 Steel: Cast 60000 to 80000 



Wrought 45000 Forgings. .60000 to 95000 



Lead: Cast 1800 Tin: Cast 3360 



Rolled Sheet 3320 Zinc: Cast 3360 



Platinum Wire 53000 Sheet 15680 



"Puddled" Semisteel: 

 Lunkenheimer 35000 to 42000 



Woods 



Ash 11000 to 17000 Locust 20500 to 24800 



Beech 11500 to 18000 Maple 10500 to 10584 



Cedar 10300 to 11400 Oak: White 10253 to 19500 



Chestnut 10500 Pine: White .... 10000 to 12000 



Elm 13000 to 13489 Pine: Yellow. . . . 12600 to 19200 



Hemlock 8700 Spruce 10000 to 19500 



Hickory 12800 to 18000 Walnut: Black . 9286 to 16000 



In designing a piece of machinery, the first thing to find 

 out is the strength of the metal or material of which it is 

 to be made. The technical meaning of " strength" is the 

 power of a body to resist force and in mechanics the word 

 "body" means any solid object. The' word " force " means a 

 push, a pull, a twist, or a cut. 



290. Weight of Metals per Cubic Inch. It is often ne- 

 cessary in designing a machine to know the weight of its 

 parts, and any good engineer's handbook will give the weights 

 per cubic inch of all the metals. Not all kinds of iron weigh 

 exactly the same, since different processes of manufacture 

 use different amounts of the materials of which it is made. 

 The same thing is true of all metals, so only the approximate 

 weight is given in the following table which shows some of 



