b from cathode particles traversing a gas. 145 
up much more rapidly, an effect easily explained if P is regarded 
as emitting negative electricity as the result of a radiation pro- 
ceeding from the cathode stream itself. A test which conclusively 
showed that the effect was really due to a radiation from the 
cathode stream was devised. A solid obstacle was placed in front 
of W, the effect at once disappeared; on removal of the obstacle, 
P again commenced to charge up. In the actual experiment the 
obstacle was a small brass plate, which could be rotated from the 
To Battery 
a 
| Te Earth 
a vard rin 
Wen "s 
§—-To Elecirosc ope 
——> 
fsx} 
_] 
t i} Lh 
To pump and charcoal! tube 
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outside by means of the ground glass joint J. In this way P 
could be given an uninterrupted view of the cathode stream or 
the view could be cut off. 
__ There is thus definite evidence of a radiation proceeding from 
the path of the cathode stream. That this radiation does not 
consist of charged particles of small mass is shown by the fact 
that it is not cut off by a transverse magnetic field. Strong 
evidence in favour of supposing it to be a very soft Réntgen 
, 
| VOL. XVIL PT, I. 10 
. 
