48 Experiments upon Gunpowder. 



&c. ; but the vent may be indifferently in any part of 

 the chamber where it will best answer upon other ac- 

 counts ; and there is little doubt but the same thing 

 will hold good in great guns, and all kinds of heavy 

 artillery. 



Almost every workman who is at all curious in fire- 

 arms has a particular fancy with regard to the best form 

 for the bottom of the chamber, and the proper position 

 of the vent. They, in general, agree .that the vent 

 should be as low or far back as possible, in order, as 

 they pretend, to lessen the recoil ; but no two of them 

 make it exactly in the same manner. Some make the 

 bottom of the chamber flat, and bring the vent out 

 even with the end of the breech-pin. Others make 

 the vent slanting through the breech-pin, in such a 

 manner as to enter the bore just in its axis. Others 

 again make the bottom of the chamber conical ; and 

 there are those who make a little cylindric cavity in 

 the breech-pin of about two tenths of an inch in diame- 

 ter, and near half an inch in length, coinciding with the 

 axis of the bore, and bring out the vent even with the 

 bottom of this little cavity. 



The objection to the first method is, the vent is apt 

 to be stopped up by the foul matter that adheres to the 

 piece after firing, and which is apt to accumulate, espe- 

 cially in damp weather. The same inconvenience, in a 

 still greater degree, attends the other methods, with the 

 addition of another, arising from the increased length 

 of the vent ; for, the vent being longer, it is not only 

 more liable to be obstructed, but it takes a longer time 

 for the flame to paj.s through it into the chamber, in 

 consequence of which the piece is slower in going off, 

 or, as sportsmen term it, is apt to hang fire. 



