EXPERIMENTS WITH THE DISPLACEMENT INTERFEROMETER. 61 



TABLE 4. Displacement of brass disk with electrical contact and without. Constants as 



in table I. 



*Next day, 71. 



at 2.15 cm. differ in like degree, so that the apparent attraction indicated is 

 merely the result of the shift of the position of equilibrium of the horizontal 

 pendulum. Series 19 and 20 contain similar observations on the other side. 



34. Observations, continued. Change of distance apart. In the following 

 work table 5 and figs. 37, 38, 3gA, 396, the attempt is again made to vary 

 the distances between fixed and movable plates, successively, but to determine 

 the micrometer position of contact of the plates by actually pushing them to- 

 gether with a weak spring. Observations are made on the "larger" side in 

 series i to 8, the distance apart increasing from position 2.15, where it is 

 0.045/2 cm., to position 2.05, where it is 0.247/2 cm., i.e., the total displace- 

 ment being about o.i cm. The observations are given in time series in fig. 

 37 and are not interrupted, until the motion of the pendulum is retrograde. 

 The doubly inflected curve, series 3, 4, 5, etc., is well shown; i.e., the plates 

 after immediate contact separate very slowly, whereupon the speed of sepa- 

 ration reaches a maximum, to decrease to zero again when the pendulum 

 regains its position of equilibrium. It is probable that in series i and 2 the 



