t40 JETS OF FIRE. 



powder, four ounces of saltpetre, two ounces of sulphur, and one 

 ounce of charcoal : the whole must be well pounded and mixed. 



Instead of roods, the globe may be charged with running rockets, 

 or paper petards, and a quantity of fiery stars or sparks mixed with 

 pulverised gunpowder, placed without any order above these pe. 

 tards, which must be choaked at unequal heights, that they may 

 perform their effect at different times. 



These globes may be constructed in various other ways, which 

 it would be tedious here to enumerate. We shall only observe, 

 that when loaded, they must be well covered at the (op ; they must 

 be wrapped up in a piece of cloth dipped in glue, and a piece of 

 woollen cloth must be tied round them, so as to cover the hole 

 which contains the match. 



CHAP. VIII. 



JETS OF FIRE. 



JETS of fire are a kind of fixed rockets, the effect of which is to 

 throw up into the air jets of fire, similar to jets of water. They 

 serve also to represent cascades ; for if a series of such rockets be 

 placed horizontally on the same line, it maybe easily seen that the 

 fire they emit, will resemble a sheet of water. When arranged in 

 a circular form, like the radii of a circle, they form what is called 

 a fixed sun. 



To form jets of this kind, the cartridge for brilliant fires must, 

 in thickness, be equal to a fourth part of the diameter, and for 

 Chinese fire; only to a sixth part. 



The cartridge is loaded on a nipple, having a point equal in 

 length to the same diameter, and in thickness to a fourth part of it ; 

 but as it generally happens that the mouth of the jet becomes 

 larger than is necessary for the effect of the fire, you must begin to 

 charge the cartridge, as the Chinese do, by filling it to a height equal 

 to a fourth part of the diameter with clay, which must be rammed 

 down as if it were gunpowder. By these means the jet will ascend 

 much higher. When the charge is completed with the composi- 



