THE EOYAL AETILLEEY INSTITUTION. 
181 
beat seconds, a further calculation is required in this case to convert beats 
into seconds. As the period from which we measure time is quite arbitrary— 
if we subtract the time of passing the first screen from the times* of 
passing the other screens, we obtain a table giving the time occupied 
by the shot in passing from the first to any succeeding screen. The 
whole must be differenced as a test of the accuracy of the work, and 
any necessary correction must be introduced. The first column of dif¬ 
ferences (A x ) represents the time of passing from screen to screen. If the 
clock used, as is intended, beat seconds, and if it be found that during the 
course of any set of experiments it does not keep exact time, but gains or 
loses 1 in 1000, say, then the times last found will require to be diminished 
or increased 1 in 1000. A small correction of this kind was required, dif¬ 
fering slightly in Bounds 1-9 and 10-18. If the clock had been perfectly 
adjusted, the length of a beat would have been 0*"81586. 
No. 
of 
Screen. 
Corrected 
Screen 
Eeading. 
Beats of 
Clock. 
Beats of 
Clock. 
Seconds. A 2 
a 2 
1 
36-188 
4-7633 
0-0000 
0-0000 •. 
0-1064 + 40 ° 4 
0-2141 + JJJ" 
0-3229 t iaqq 
2 
37-195 
4-8935 
0-1302 
+ 13 
3 
38-212 
5-0252 
0-2619 
+ 11 
4 
39-240 
5-1583 
0-3950 
+ 11 
5 
40-278 
6-2927 
0-5294 
0,4328 + 1109 
0-5437 + 
+ 10 
6 
41-325 
5-4284 
0-6651 
+ 10 
7 
42-379 
5-5652 
0-8019 
+ 7 
8 
43-439 
5-7029 
0-9396 
0-7682 + j 420 
0-8814 + 4132 
0-9950 + 1136 
+ 6 
9 
10 
44- 505 
45- 576 
5.8413 
5-9804 
1-0780 
1-2171 
+ 4 
Tor the remaining 10 rounds it will be sufficient to give the clock and 
screen readings and their corrections. 
EOUND 2. 
Clock. 
Screens. 
Eeading. 
Correction. 
Corrected 
Eeading. 
No. 
Eeading. 
Correction. 
Corrected 
Eeading. 
Time. 
Ai 
a 2 
5-030 
•000 
5-030 
1 
32-993 
- -001 
32-992 
// 
0-0000 
+ 1045 
+ 1053 
+ 1062 
+ 1072 
+ 1087 
+ 1103 
+ 1116 
+ 1132 
+ 1148 
10-700 
+ -005 
10-705 
2 
* * * 
33-713 
•1045 
+ 8 
16-370 
+ -001 
16-371 
3 
34-435 
+ -004 
34-439 
•2098 
+ 9 
22-030 
- -002 
22-028 
4 
35-175 
- -004 
35-171 
•3160 
+ 10 
27-680 
- -003 
27-677 
5 
35-905 
+ -005 
35-910 
•4232 
+ 15 
33-320 
•000 
33-320 
6 
36-665 
- -005 
36-660 
•5319 
+ 16 
38-950 
+ -007 
38-957 
7 
37-425 
- -005 
37-420 
•6422 
+ 13 
44-590 
•000 
44-590 
8 
38-190 
•000 
38-190 
•7538 
+ 16 
9 
38-970 
•000 
38970 
•8670 
+ 16 
10 
39-760 
•000 
39-760 
•9818 
[VOL. V.] 
24 
