654 
MR. W. CROOKES ON MOLECULAR PHYSICS IN HIGH VACUA. 
The clotted arrows represent the directions taken by the molecular stream when the 
current circulated round the magnet. The blunt end is stationary, as the starting 
point of the molecules—the hole in the mica plate—did not move; the point shows 
the direction in which the spot of light moved across the phosphorescent screen, and 
the slope of the dotted arrow shows the deflection given to the molecular stream. 
The feathered arrows have nothing to do with the molecular stream, but indicate the 
direction of the electric current round the magnet. 
613. When the molecular ray was at the S end, the movement was to the right 
when the stream was upwards, and to the left when the stream was downwards. A 
section at this point (along the line a b) shows no movement when looking in the 
direction of the axis, as the rays only move to and fro along the line of sight. 
In the centre of the magnet the rays are moved inwards or outwards according to 
their direction, the upward stream going from, and the downward stream to the 
observer. This cannot be seen on the horizontal magnet but is shown in the section 
across c cl. Although this section is supposed to be across the centre of the magnet, 
I have marked it S, as the observer is supposed to be looking at it from the S end. 
At the N end of the magnet the action is the same in degree, but opposite in direc¬ 
tion to that at the S end. It is shown by the section across e f. 
Fig. 15. 
Section across a b. Section across c d. Section across ef. 
614. The magnet being in the same position as before, the indicator tube was turned 
so that the stream of molecules should move in a direct line to or from the observer, 
Fig. 16. 
Molecules moving to the observer. 
and it was carried round in a vertical plane passing through the axis of the magnet. 
The dotted arrows in fig. 16, show the deflection suffered by the stream of molecules 
in the different positions. The line of molecules when not under magnetic influence 
