rotating disk. The mean of ten determinations gave λ = 5700± 50 angstroms.
The displacement of the fringes due to the earth’s rotation was measured on many different days, with complete readjustments of the mirrors, with the reflected image sometimes on the right and sometimes on the left of the transmitted image, and by different observers. The deflections were averaged usually in sets of twenty, in the order in which they were taken. The resulting means are given in Table I. The entire set of two hundred and sixty-nine determina-
TABLE I
|
Observation* |
Displacement in Fringes |
Number of Observations |
Deviation from Mean |
|
1 |
0.252 |
20 |
0.022 |
|
2 |
.255 |
20 |
.025 |
|
3 |
.193 |
20 |
.037 |
|
4 |
.246 |
20 |
.016 |
|
5 |
.235 |
20 |
.005 |
|
6 |
.207 |
26 |
.023 |
|
7 |
.232 |
20 |
.002 |
|
8 |
.230 |
20 |
.000 |
|
9 |
.217 |
20 |
.013 |
|
10 |
.198 |
20 |
.032 |
|
11 |
.252 |
20 |
.022 |
|
12 |
.237 |
20 |
.007 |
|
13 |
0.230 |
23 |
0.000 |
|
Mean 0.230 |
Total 269 |
Av. dev. from Mean 0.016 |
* Observations 1 and 2 corrected for direct image only; 1-6 inclusive, without collimator; 7-13 inclusive, with collimator.
tions and their distribution about the mean value is shown graphically in Figure 3. The final displacement, expressed as a fraction of a fringe, is
0.230±.005 obs. 0.236±.002 calc.
In view of the difficulty of the observations, this must be taken to mean that the observed and calculated shifts agree within the limits of observational error.
The successful completion of this experiment is due in no small measure to the friendly co-operation of the officials of the City of
|
Obs. |
Calc. | |
|
Displacement... |
0. 230± .002 |
0. 236± .002 |
Chicago, Colonel A. A. Sprague, commissioner of public works; Mr. H. L. Lucas, superintendent of the Water Pipe Extension Division, and to Mr. B. W. Cullen, superintendent of the South District of the same Division; to the courtesy of the Clearing
Fig. 3.—Distribution of observations
Industrial District, through Mr. Henry H. Porter; to the kindness of the Chicago Telephone Company, and to the hearty and enthusiastic support of the University. We are especially indebted to President Burton, Mr. J. C. Dinsmore, Mr. L. R. Flook, and to Messrs. Thomas O’Donnell, Joseph Purdy, and Charles Stein.
Ryerson Physical Laboratory University of Chicago March 1925