1879.] 



on Molecular Phi/sics in Iligh Vacua. 



155 



(Fig. 16) is furnished with a negative pole in the form of a cup (h). 

 The rays will therefore be projected to a focus in the middle of the 

 tube (Fig. 17, a). At the side of the tube is a small electro-magnet, 



]>! 'A 



