OF FLUIDS ON THE MOTION OF PENDULUMS. 

 Baity' a results with spheres suspended byjine wires. 



[69] 



The mean error in different determinations of tl for the same sphere was about 0-01 or 0-02, 

 and this does not include errors arising from small errors in specific gravities, &c. Hence, if 

 we except the spheres Nos. 1, 2, and 4, the discrepancies between theory and experiment are 

 altogether insignificant. In considering the confirmation thence arising to the theory, it must 

 be borne in mind that the theory did not furnish a single disposable constant, inasmuch as 

 \/V was already determined from the experiments with cylindrical rods. The result obtained 

 with the brass sphere No. 3 happens to agree almost exactly with theory. However, as the 

 results obtained with this sphere exhibited some anomalies, it seems best to exclude it from 

 consideration. The value of It, then, which belongs to a l^inch sphere, appears to exceed 

 by a minute quantity the value deduced from theory. The difference is indeed so small that 

 it might well be attributed to errors of observation, were it not that all the spheres tell the 

 same tale. Thus the error + 0046 in the case of the platina sphere corresponds to an error of 

 less than the fortieth part of a second in the observation of an interval of time amounting to 

 4^ hours. If the apparent defect, amounting to about 0'04 or - 05, in the theoretical result 

 be real, it may be attributed with probability to an error in the correction for the wire. This 

 would be no objection to the theory, for it will be remembered that the theory itself indicated 

 the probable failure of the formula? generally applicable to a long cylinder when the cylinder 

 comes to be of such extreme fineness as the wires employed in pendulum experiments. 



58. The preceding experiments of Baily's are the most important for the purposes of the 

 present paper, inasmuch as they were performed on pendulums of simple and very different 

 forms; but there still remain three sets of experiments, the fourteenth, fifteenth, and six- 

 teenth, in which the pendulum consisted of a combination of a sphere and a rod, so that the 

 results can be compared with theory. The details of these experiments being suppressed, I 



