RiGBY — On the Velocity and Energy of Small Shot. 29 



air resistance, these sources of error may balance one another to a 

 considerable degree. 



The measurement of the diameter and weight of small shot of 

 various sizes, which are designated by the trade numbers of 1, 2, 

 3, 4, &c., is rendered troublesome by the fact that the British 

 makers seem to have selected their size at random, and no two 

 makers agree as to the exact weight of pellet to which they give 

 any particular number. In America, the jQrm of Tatham and 

 Brothers has adopted a more satisfactory plan, and instituted an 

 "American Standard." They tak^ the diameter of their largest 

 dropshot as '23 of an inch, which gives twenty-four pellets to the 

 ounce, and manufacture twenty-one sizes, each successive number 

 being "01 less in diameter than the preceding, until their fine dust- 

 shot is reached, at a diameter of '03 ; in addition to which, they 

 make an extra-fine size, with diameter of '015, and weight of 

 84020 to the ounce. For convenience of computation, I have taken 

 three of their sizes, viz. : — 



No. 1, diameter "16, weight 



No. 7, „ -10, 

 No. 9, „ -08, 



1 oz. 



TT' 



1 oz, 

 291' 

 1 oz. 

 568' 



These represent the first, heavy shot used for wild-fowl ; the 



second, the shot in most general use, and called No. 6 by English 



makers ; and the third, snipe-shot (Nos. 8 or 9, English) . 



rp 

 The values of r= for these sizes are, respectively. 



No. 1, 29-08. No. 7, 46-56. No. 9, 58-16. 

 If I now select from the observed ■ velocities of the medium- 

 sized shot at 60 feet, 840 f. s., as a representative one for the 

 ordinary charge of a good gun, and calculate by the Tables the 

 remaining velocities at intervals of 60 feet, we get the following : — 



American No. 7 shot, 291 to the oz., . . W= -000215. 



Yelooity at muzzle, ' 1270 f. s. Energy. 



„ 20 yards, 840 „ 2-36 lbs. 



40 „ 634 „ 1-34 „ 



60 „ 509 „ 0-86 „ 



