432 



THE STRENGTH 



From these results it appears that in every 

 instance, except one, in the above table, the 

 deflections from extension are greater than those 

 from compression by equal forces, whether 

 the elasticity be perfect or not; the four first 

 having been taken before the elasticity could 

 have been much injured, and the last four 

 nearly at the breaking point. Still the differ- 

 ence is not so great, but that they may in 

 most cases, without material error, be assumed 

 as the same. Hence, the extensions and 

 compressions from equal forces in cast iron, 

 are nearly equal. 



21. This is a very interesting fact: it is most 

 likely a property common to tenacious bodies, 

 when not over-strained generally :* it has 



* Timber seems to be in some degree an exception; see 

 my Paper al)ove referred to. 



