256 W. Crookes—Radiant Matter. 
negative pole may be likened to a discharge of iron bullets 
from a mitrailleuse, and the magnet beneath will represent the 
earth curving the trajectory of the shot by gravitation. Here 
on this luminous screen you see the curved trajectory of the 
shot accurately traced. Now suppose the deflecting force to 
remain constant, the curve traced by the projectile varies with 
the velocity. If I put more powder in the gun the velocity 
will be greater and the trajectory flatter, and if I interpose a 
denser resisting medium between the gun and the target, I 
diminish the velocity of the shot, and thereby cause it tomove 
in a greater curve and come to the ground sooner. I cannot 
well increase before you the velocity of my stream of radiant 
molecules by putting more powder in my battery, but I will 
try and make them suffer greater resistance in their flight from 
one end of the tube to the other. T heat the caustic potash 
with a spirit-lamp and so throw in a trace more gas. Instantly 
the stream of Radiant Matter responds. Its velocity is 1m- 
peded, the magnetism has longer time on which to act on the 
individual molecules, the trajectory gets more and more 
curved, until, instead of shooting nearly to the end of the tube, 
my molecular bullets fall to the bottom before they have got 
more than half-way. 
It is of great interest to ascertain whether the law governing 
the magnetic deflection of the trajectory of Radiant Matter Is 
the same as has been found to hold good at a lower vacuum. 
The experiments I have just shown you were with a very high 
vacuum. Here is a tube witha low vacuum. When I turn 
on the induction spark, it passes as a narrow line of violet 
light joining the two poles. Underneath I have a powerfu 
electro-magnet. I make contact with the magnet, and the line 
of light dips in the center toward the magnet. I reverse the 
poles, and the line is driven up to the top of the tube. Notice 
the difference between the two phenomena. Here’ the action 
is temporary. The ne takes place under the magnetic influ- 
ence; the line of discharge then rises and pursues its th to 
the positive pole. In the high exhaustion, however, alter the 
stream of Radiant Matter bad dipped to the magnet it did not 
recover itself, but continued its path in the altered direction. 
By means of this little wheel, skillfully constructed by Mr. 
— ogham I am able to show the magnetic deflection in the 
1 Pip: ose _ The ratus is shown in this diagram (fig- 
‘). “he negative pole (a, b) is in the form of a very shallow 
cup. In front of the cup is a mica screen (c, d), wide enow h 
ne tie the Radiant Matter coming from the negative pore 
. 
re 13 screen is a mica wheel (e, f) with a series of vanes, 
making a sort of paddle-wheel. So arranged, the molecular 
ys from the pole a 6 will be cut off from the wheel, and will 
