JETS OP FIRE. 241 



tion you have made choice of, the cartridge must be closed with a 

 fompion of wood, above which it must be choaked. 



The train or match must be of the same composition as that cm. 

 ployed for loading ; otherwise the dilatation of the air contained iu 

 the hole made by the piercer, would cause the jet to burst. 



Clayed rockets may be pierced with two holes near the neck, in 

 rder to hate three jets in the same plane. 



If a kind of top, pierced with a number of holes, be added to 

 them, they will imitate a bubbling fountain. 



Jets intended for representing sheets of fire ought not to be 

 choaked. They must be placed in a horizontal position, or in. 

 clined a little downwards. 



It appears to us that they might be choaked so as to form a kind 

 of slit, and be pierced in the same manner ; which would contri- 

 bute to extend the sheet of fire still farther. A kind of long nar- 

 row mouth might even be provided for this particular purpose. 



PRINCIPAL COMPOSITIONS FOR JETS OF FIRE. 



1st. Jets of Jive lines or less, of interior diameter. 



Chinese Jire. Saltpetre 1 pound, pulverised gunpowder 1 

 pound, sulphur, 8 ounces, charcoal 2 ounces. 



White Jire. Saltpetre 1 pound, pulverised gunpowdrr 8 ounces, 

 sulphur 3 ounces, charcoal 2 ounces, iron sand of the first order 

 8 ounces. 



2d. Jets of from ten to t&elve lines in diameter. 



Brilliant Jire. Pulverised gunpowder 1 pound, iron-filings of a 

 mean size, 5 ounces. 



White Jire. Saltpetre 1 pound, pulverised gunpowder 1 pound, 

 sulphur 8 ounces, charcoal 1 ounces. 



Chinese Jire. Saltpetre 1 pound 4 ounces, sulphur 5 ounces, 

 sand of the third order 12 ounces. 



3d. Jett ofjifteen or eighteen line in diameter. 



Chinese fire. Saltpetre 1 pound 4 ounces, sulphur 7 ounces, 

 charcoal 5 ounces, of the six different kinds of sand mixed 12 

 ounces. 



Fere d'Incarville, in his memoirs on this subject, gives various 

 other proportions for the composition of these jets ; but w must 



VOL. IT. E 



