VOL. XLII.] PHILOSOPHICAL TBANSACTION8. 603 



the charge of powder and all other circumstances continue unchanged ? The 

 committee are of opinion, that the change of the form, in the chamber, will 

 produce a change of the distance to which the bullet is thrown. Their opinion 

 is grounded on the following experiments, in which the longest chamber of 

 equal capacity drove the ball farthest. 



Three brass chambers were made, whose depths were respectively 3 inches ; 

 14- inch ; and 4 inch ; so turned as to fit the chamber of Mr. Hauksbee's mor- 

 tar ; each of these chambers contained, when full, 1 oz. Troy of powder. The 

 ball was of brass, weighing 24lb. 6-i-oz. Avoirdupois, that is, nearly 356 ounces 

 Troy.* 



The ball touched the powder of the charge in all these experiments. W 

 the first chamber of 3 inches deep, the elevation of the mortar being 45°, the 

 ranges at 4 different trials were found to be as below. 

 Shot. Chains. Links. 



I 11 39 or nearly 752 feet. 



II 10 38 685 



III 11 17 737 



IV 11 10 733 



In the 2d of these experiments, the brass chamber, not being sufficiently 

 thrust home before the discharge, was by the violence of the pqwder driven in 

 so, that it could not be got out again without the help of an iron screw, and a 

 vast force applied to iron wedges. This was doubtless the cause of the great 

 irregularity observed in this case. The mean distance, collected from the other 

 3 experiments, is nearly 741 feet. 



Then 3 discharges were made with the chamber ^ of an inch deep, with ball, 

 powder, and elevation, as before. The ranges were. 

 Shot. Chains. Links. 



I. 7 6 or 466 feet nearly, 



II 7 2 463 



III 72 463 



The mean distance to which the ball was thrown in these 3 experiments is 

 464 feet. 



The chamber 14^ inch deep, was also tried ; but this not fitting the mortar so 

 well as the other 2, the ranges were found to be very irregular, being 

 Shot. Chains. Links. 



1 10 40 or nearly 686 feet. 



II 9 6 598 



III 7 8 467 



• Supposing 14 oz. U dwts. and 15 grs. and a half Troy, equal to 1 pound Avoirdupois. — Orig. 



4 H2 



