284 REPORT — 1861. 



5. Resistance to Compression. 

 The results on compression have no direct bearing on the resistance to 

 projectiles ; it is not therefore necessary to give an abstract, 



6. Statical Resistance to Punching. 



These experiments were arranged in three series -with a view to determine 

 the resistance to punching with different sizes of shot, with different thick- 

 nesses of plate, and with flat- and round-faced punches. 



First Series of Experiments. 



In this series the punch was flat-faced, and in all respects similar to the 

 projectile of the wall-piece employed at Shoeburyness. The resistance of the 

 plates was as follows : — 



Thickness of Mark of Statical Resistance 



Plates in inches. Plates. to punching in lbs. 



^ A 29,604 



B 19,428 



C 31,604. 



D 18,980 



A 57,956 



B 57,060 



C 71,035 



D 49,080 



84,587 



0-25 



0-50, 



0-75 



|B 



\ D 82,381 



The shearing strain varied from 13 to 20 tons per square inch in the case 

 of iron, and from 21 and 23 tons with homogeneous metal. 



Second Series of Experiments, 



Punch flat-faced, and half an inch in diameter. Hole in die-block beneath 

 1| inch diameter. The resistances to punching were as the following 

 numbers: — 



Thickness of Mark of Statical Resistance 

 Plates in inches. Plates. to punching in lbs. 

 {A 33,980 



n.rn ■ \^ ^^^'972 



"^" ) C 48,100 



[D 31,345 



f B 46,996 



0-75 . . ; -^ C 48,788 



[ D 48,146 



1-00 P 62,584 



^^ \ D 60,696 



In this case the shearing stress per square inch of section varied from 17 

 to 19| tons in the case of iron, and from 18g to 27 tons in the homogeneous 

 metal. 



In both these series the plates stand in the same order of merit, which is 

 also identical with that in whicii they were placed as regards tenacity and 

 density, viz., C, A, B, D. Their relative value is as follows : — 



A plates 1-000 



B plates 0-907 



C plates 1-168 



D plates 0-873 



