Nipher — Gravitational Repulsion. 



183 



ciably change the result. It was finally decided to check 

 the results above described by placing the large masses 

 on alternate sides of the suspended masses and observ- 

 ing the deflection due to gravitational attraction. 



In order to maintain equality of stresses in the two 

 threads, which had been hung around a hook attached to 

 the torsion head, they were hung around a pulley, having 

 a diameter of one inch. Below were two adjustable 

 pulleys. The threads approached each other around 

 these two pulleys, and their distance apart could be so 

 varied as to make the threads parallel within the long 

 suspension cylinder. The metal shield before described 

 was replaced by one having equal width from end to end. 

 The top, bottom and ends were of wood % i ncn i n thick- 

 ness. A sketch of this wood frame is shown in vertical 

 section in Fig. 1. 



JilL 



Fig. 1. 



This wood frame was varnished with shellac and all 

 points of contact of its parts were closed. The sides of 

 this frame were each closed by two layers of heavy card- 

 board outside of which was a sheet of flexible tinned iron. 

 They were clamped to the wooden frame by means of 

 wood bars screwed to the bottom, top and ends. The 

 edges of the cardboard were then sealed by means of 

 beeswax applied by means of a hot iron. The entire de- 

 vice as thus described was then enclosed by a metal shield. 



