108 



DISPLACEMENT INTERFEROMETRY APPLIED TO 



double amplitudes from triplets. This has been done, and the value of Ay is 

 inscribed in each of the consecutive zigzags of reasonable shape. The mean 

 values are 



Series i t=i m Ay = o.i62 io 3 



,m 



O.6OO 



8-73 



4-6 



The apparent value of 7 in each case is but little more than two-thirds of 

 the standard value and the deficiency must be ascribed to the coefficient of 

 friction neglected. It is interesting, however, to note that relatively equation 

 (i) is roughly corroborated, the displacement A% being (here) 4 times as 

 large in two minutes as in one minute, though the motion itself is far from 

 uniformly accelerated. 



In figure 122 the needle moves, as it were, without inertia and the phase 

 difference (Ap) relative to the forces is therefore 90, but the period is too 

 short for much discrimination, particularly in view of the drift. In figure 123, 

 however, the same anomalous condition reappears and, what is more striking, 

 is the retarded motion between the turning-points. For this is of the nature 

 of a lag, or indicates an apparently waning gravitational effect, or rather the 

 growth of some repulsive force. 



$0 40 



On July 7 , I made another series of observations given in figures 1 2 4 to 127 

 for one, two, and three minute periods. Figures 124 and 126 made before and 

 after figure 125 and for one-minute periods show no gravitational effect, but a 

 mere drift with several induplications. At least, if triplets were constructed, 

 they would have a value not exceeding A# = 0.0007 centimeter about one- 

 twelfth the value in figure 122. During the first minute gravity shows no 

 appreciable preponderance. During the ensuing one and two minutes, *. e., for 



