Smithsonian Report. 1964. — Field 



PLATE 3 



1. Fractures produced on the surface of a ji inch thick glass plate by the impact of a liq- 

 uid cylinder at 4,000 feet per second. The "bands" of fracture are caused by the rein- 

 forcement of the Rayleigh Surface wave by stress waves reflected from the rear surface 

 of the plate. (Magnification X 1.04.) 



2. W'allncr lines found on the fracture surface of a glass plate. Since they are formed by 

 the interference of the fracture front with transverse stress waves it is possible to de- 

 termine the fracture velocity. (Magnification X 6.5.) 



