58 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



TABLE XVIII. 



[lO-gange Colt gun; 4 drauis Curtis & Harvey jiowder; IJ-ounce shot.] 



Table XIX. 



[la-gauge Colt gun ; 3J- drams of Curtis & Harvey powder ; IJ-onnce shot. ] 



Table XX. 



[12-gauge Colt gun; 4 drams Curtis & Harvey powder; IJ-ounce shot.] 



Bach measure of velocity given in these tables is the mean value obtained from several experi- 

 ments, varying in number from three to six. The headings " velocity 30, 40, 50 yards," mean that 

 the numbers under them give the average velocities of the flight of shot over those distances, and 

 not the velocities at 30, 40, and 50 yards from the gun. 



It will be observed that the shot used were Nos. 10, 8, 6, 3, BB, FF, and No. 1 Buck. They 

 were so selected because a pellet of any number in the above series weighs nearly double the pre- 

 ceding one. Thus a pellet of No. 8 weighs double one of No. 10, a pellet oi' No. 6 weighs double one 

 of No. S, and so on. These relations of weight among the pellets were obtained so that I could 

 readily reach the relations existing between the velocities and the weights of pellets. The shot 

 used was kindly furnished me by Tatham & Bros., of New York, who used carefully gauged sieves 

 in their manufacture. The powder used was Curtis & Harvey's Diamond Grain No. (J. The powder 

 and shot in each cartridge had been carefully weighed out in an accurate balance. 



A glance at the tables at once shows the rapid increase in the velocity of the shot from 

 No. 10 up to No. 3. With the heavier pellets the increase is less marked. Thus the table headed 

 "10 Colt gun; 4 drams, Curtis & Harvey, 1:^ shot," shows that No. 8 shot has 72 feet per second 

 velocity over No. 10 shot, and No. 6 has 46 feet over No. 8, while No. 3 has only 23 feet over No. 6, 

 and BB shot gains only 11 feet over No. 3. 



The relations between velocity and weight of pellet shown in this table may be taken as a type 

 of all the experiments, and I have graphically shown their relations in the accompanying curve. 



