Observations of the double displacement A.
1st Series. l=3.022 meters =8.72 meters per second |
=double displacement; w=weight of observation.
. | w. | . | w. | . | w. | . | w. |
.510 .508 .504 .473 .557 .425 .560 .544 .521 .575 |
1.9 1.6 1.7 1.4 .4 .6 2.9 .1 .1 .1 |
.521 .515 .575 .528 .577 .464 .515 .460 .510 .504 |
0.9 .9 .6 2.1 .6 1.7 1.2 .4 .5 .5 |
.529 .474 .508 .531 .500 .478 .499 .558 .509 .470 |
0.6 2.0 1.4 .8 .5 .6 1.0 .4 2.0 2.1 |
.515 .525 .480 .493 .348 .399 .482 .472 .490 |
2.5 2.7 .8 10.6 2.8 5.7 2.1 2.0 .8 |
2d Series. l=6.151, =7.65.
. | w. | . | w. | . | w. | . | w. |
.789 .760 .840 .633 .876 .956 |
4.9 3.5 4.6 1.1 7.3 3.6 |
.891 .883 .852 .863 .863 .820 |
1.7 2.5 11.1 1.5 1.1 3.4 |
.909 .899 .832 .857 .848 .877 |
1.0 1.7 4.3 2.1 1.9 4.7 |
.399 .908 .965 .967 |
6.6 5.9 2.0 3.3 |
3d Series. l=6.151, .
. | w. | . | w. | . | w. | . | w. |
.640 | 4.4 | .026 | 11.9 | .636 | 3.1 | .619 | 6.5 |
If these results be reduced to what they would be if the tube were long and the velocity per second, they would be as follows:
Series | . |
1 2 3 |
.1858 .1838 .1800 |
The final weighted value of for all observations is . From this, by substitution in the formula, we get
with a possible error of .
The experiment was also tried with air moving with a velocity of 25 meters per second. The displacement was about of a fringe; a quantity smaller than the probable error of observation. The value calculated from would be .0036.
It is apparent that these results are the same for a long or short tube, or for great or moderate velocities. The result was also found to be unaffected by changing the azimuth of the fringes to 90°, 180° or 270°. It seems extremely improbable that this could be the case if there were any serious constant error due to distortions, etc.