THE EOYAL ARTILLERY INSTITUTION. 
i 85 
The irregularity at the 9th and 10th screens is caused by the failure of a 
few screens in rounds 5, 11, and 15. We can now, by means of a common 
interpolation formula calculate the average time occupied by the shot in 
moving over 20 feet, or of 120 feet, from each screen. And dividing 20 
by this fraction of a second, we obtain the velocity of the shot at 130, 250, 
370, &c. feet from the gun. 
Distance Velocity, 
from gun. f.s. 
ft. 
130 1149-4 
250 1135-7 
370 1122-6 
490 1109-9 
610 1097-7 
730 1086-1 
850 1075-0 
970 1064-3 
Ai A 2 
-13-7 
-13-1 
-12-7 
- 12-2 
- 11-6 
- 11-1 
-10-7 
+ *6 
+ -4 
+ *5 
+ *6 
+ *5 
+ *4 
By interpolation we are now able to obtain from experiment alone the 
average velocity of the eleven shot at every ten feet from the gun, from 130 
to 1000 feet. The result is 
Distance^ 
from 
gun. 
Velocity. 
Distance 
from 
gun. 
Velocity. 
f.s. 
Distance 
from 
gun. 
Velocity. 
f.s. 
Distance 
from 
gun. 
1 
1 Velocity, 
f.s. 
ft. 
ft. 
ft. 
ft. 
130 
1149-4 
360 
1123-6 
590 
1099-7 
820 
1077-7 
140 
1148-2 
370 
1122-6 
600 
1098-7 
830 
1076-8 
150 
1147-1 
380 
1121-5 
610 
1097-7 
840 
1075-9 
160 
1145-9 
390 
1120-4 
620 
1096-8 
850 
1075-0 
170 
1144-8 
400 
1119-4 
630 
1095-8 
860 
1074-1 
180 
1143-6 
410 
1118-3 
640 
1094-8 
870 
1073-2 
190 
1142-5 
420 
1117-2 
650 
1093-8 
880 
1072-3 
200 
1141-3 
430 
1116-2 
660 
1092-9 
890 
1071-4 
210 
1140-2 
440 
1115T 
670 
1091-9 
900 
1070-5 
220 
1139-0 
450 
1114-1 
680 
1090-9 
910 
1069-6 
230 
1137-9 
460 
1113-0 
690 
1089-9 
920 
1068-7 
240 
1136-8 
470 
1112-0 
700 
1089-0 
930 
1067-8 
250 
1135-7 
480 
1110-9 
710 
1088-0 
840 
1066-9 
260 
1134-6 
490 
1109-9 
720 
1087-1 
950 
1066-1 
270 
1133-5 
500 
1108-8 
730 
1086-1 
960 
1065-2 
280 
1132-4 
510 
1107-8 
740 
1085-2 
970 
1064-3 
290 
1131-3 
620 
1106-8 
750 
1084-3 
980 
1063-4 
300 
1130-2 
530 
1105-8 
760 
1083-3 
990 
1062-6 
310 
1129-1 
540 
1104-7 
770 
1082-4 
1000 
1061-7 
320 
1128-0 
550 
1103-7 
780 
1081-5 
330 
1126-9 
560 
1102-7 
790 
1080-5 
340 
1125-8 
670 
1101-7 
800 
1079-6 
350 
1124-7 
580 
1100-7 
810 
1078-7 
i 
Supposing that the average times occupied by the shot in travelling from 
the first to each succeeding screen were expressed in seconds carried to only 
three places of decimals, the second differences of the time would be nearly 
constant. If they were exactly constant, then the time t occupied by the 
shot in passing from the first screen to a point s feet from it, would be 
