48 C. E Munroe — Effects of Detonation of Gun-cotton. 



Art. Y. — Wave-like effects produced by 

 Gun-cotton ; by Chaeles E. Munroe. 



the Detonation of 

 With Plate IY. 



Haying had occasion recently to determine how readily 

 gun-cotton which was completely saturated with water could 

 be detonated, I employed for the purpose a tin can, with a 

 smooth flat bottom to hold the gun-cotton disk and then filled 

 the can with sufficient water to just completely cover the disk. 

 A paraffined dry disk of gun-cotton, to serve as a primer, was 

 then laid directly on top of and in contact with the wet disk, 

 and a detonator containing thirty-five grains of mercury fulmi- 

 nate was inserted in the primer for the purpose of firing it. 



in fig. 1, where A. represents the 



The arrangement is shown 



can. 



-j 

 B 



the disk of wet gun- 

 cotton, C the disk of dry gun- 

 cotton, D the detonator, E the 

 water and F the iron beam on 

 which it rested. The gun- 

 cotton disks had a diameter 

 of 3J inches each, while the 

 can had a diameter of Sc- 

 inches and, as the gun-cotton 

 disks were ]3laced with their 

 cylindrical axes parallel to 

 that of the can and with one 

 face in contact with the side 

 of the can, there was a cres- 

 cent-shaped space about the gun-cotton at the bottom of the 

 can, two inches wide at its greatest width, which was covered 

 by water only. 



The can, with its contents arranged as described, was placed on 

 the smooth face of a heavy wrought iron beam and detonated. 

 The effect produced on the iron is shown in fig. 2 (Plate IY), 

 which is reproduced from a photograph, of such pieces of the 

 fractured beam as were recovered. Inspection of the impressed 

 surface shows a comparatively smooth and deep indentation 

 immediately under the place occupied by the gun-Qotton, which 

 has an area nearly equal to that of the base of the gun-cotton 

 disk. Surrounding this is a crescent-shaped space, about five- 

 eighths of an inch wide at its greatest width, which appears 

 slightly undulating when examined by a low-powered lens, 

 and then follows a series of breakers, concentrically arranged 

 about the impression of the base of the gun-cottou disk, which 

 are plainly visible to the naked eye. These breakers appear to 

 consist of lines of waves which are undulating in paths nearly 

 normal to the direction of propagation of the breakers, while 



