Nipher — Gravitational Repulsion. 187 



The possibility that one terminal of the machine pro- 

 duced greater heat effects than the other, the deflecting 

 effect being decreased when the terminal producing the 

 lesser heating effect was applied is also eliminated. It 

 matters not which terminal is first applied. The result 

 is the same, and has been obtained many times. 



During the afternoon of May 4 the operation repre- 

 sented in the upper curve of Plate XLV was repeated, 

 the positive terminal being first applied. A result of pre- 

 cisely the same kind was obtained. 



The upper curve of Plate XLV also means that the gra- 

 vitational attraction between the masses at 9 :35 a. m. had 

 been decreased by about 110% at 10:10 a. m. Gravita- 

 tional attraction had been decreased to zero, and had then 

 been converted into a repulsion. An hour later it had 

 regained its initial value. On the afternoon of June 1, at 

 2 :30 p. m., it was decided to change the electrical condi- 

 tion of the suspended masses. One of the end caps form- 

 ing the outer metal shield of Fig. 2 was removed. A hole 

 which had been bored through the wood frame, and which 

 had been closed by a rubber stopper, was opened. A glass 

 tube was passed through the opening, about two centi- 

 meters beyond the inner surface of the wood frame. A 

 copper wire to the end of which the head of a pin had 

 been soldered, was passed through the tube, the point of 

 the pin projecting slightly beyond the end of the tube. 

 The wire was about six inches in length. The apparatus 

 was arranged as shown in Fig. 3. The positive terminal 

 of the machine was used in draining negative corpuscles 

 from the air within the shield around the suspended 

 masses. A slow change of 1.2 cm. or 12 scale divisions 

 in the scale reading was produced. The terminal was 

 disconnected when this deflection had been produced, and 

 the machine was stopped. The tube was removed, the 

 end cap of metal was replaced and the large masses and 

 shield and the pin-point conductors were grounded until 

 the next day. The mean reading had not been appre- 

 ciably changed. 



