Experiments tcp07i Gunpowder. 71 



diameter, which, being placed at a proper distance from 

 the end(<^) of the ramrod that goes up into the bore, will 

 prevent its being thrust up too far. This ring may be 

 made of wood or of any kind of metal, as shall be found 

 most convenient. The other end of the ramrod [b) 

 may be 31 or 32 inches in length from the ring, and the 

 extremity of it being covered with a proper substance, 

 it may be made use of for wiping out the barrel after 

 each experiment. 



The machine (/) for the tape to slide through may 

 be the same as that described by Dr. Hutton in his ac- 

 count of his experiments on the initial velocities of 

 cannon balls, as his method is much better calculated 

 to answer the purpose than that proposed and made use 

 of by Mr. Robins. I twill also be better for the axis of 

 each of the pendulous rods to rest upon level pieces 

 of wood or iron, than for them to move in circular 

 grooves ; care must however be taken to confine them 

 by staples, or by some other contrivance, to prevent 

 their slipping out of their places. 



The trunnions, by means of which the barrel is con- 

 nected with the pendulous rods and upon which it is 

 supported, should be as small as possible, in order to 

 lessen the friction ; and for the same reason they should 

 be well polished, as well as the grooves which receive 

 them. They need not be cast upon the barrel, but may 

 be screwed into it after it is finished. 



In making the experiments, regard must be had to the 

 heat of the barrel as well as to the temperature and state 

 of the atmosphere ; for heat and cold, dryness and 

 moisture, have very sensible effects upon gunpowder, 

 to increase or diminish its force. If therefore a very 

 great degree of accuracy is at any time required, it will 



.^^" 





