ON ENERGY OF RONTGEN AND BECQUEREL RAYS, ETC. 
4y 
A and BCD, were fixed on a liglit Avooden frame. The plate opposite to A AAoas cnt 
into three parts, B, C, D, and (J AAms insulated fi'oni B and D. The ])late A A\ as 
connected to one pole of a battery of 310 \mlts, the other j)ole of AA4iic]i Avas connected 
to earth. The plate (J aa^.s connected to one })air of quadrants of the electroineter, 
the other pair of AAdiich aa^s connected to earth. Tlie plates B and D AAmre in 
connection Avith the CAdinder, AAdiich AAors also connected to earth. The plates B and 1) 
tlius corresponded to a partial guard ring for the plate 0, and sei’Amd tA\aA jiuipioses. 
The electric field aa^s rendered uniform from C to A, and most of the secondary 
radiation set up at the tAAm ends of the c}dinder Avas absorbed betAA^en A and B and 
between A and D, and thus did not produce apprecialde ionization lietAAmen A and C. 
A large lead plate, L, AAuth a rectangnlar orifice, aauis so placed tiiat tlie rays from the 
source passed into the cylinder, and did not fall on tlie parallel jilates. This aAuiided 
the presence of secondary radiation. The tAA’o ends of the cylinders Avere coAmred 
inside AAuth cardboard in order to make the amount of secondary radiation as small as 
possible. The amount of radiation set up at the surface of air and cardboard is very 
small. The amount of insulating material inside the cylinder aauas reduced as far as 
possible in order to aAmid the collection of free charges on them, and consequent 
disturbance of the electric field. For tliis reason the plates AAmre mounted on a 
wooden frame instead of an ebonite one. The AAmod Avas a sufficiently good conductoi' 
to quickly discharge any electrification that readied its surface. 
Fig. 6. 
The current lietAA^een C and A is thus due only to the ions AAdiich AAmre produced liy 
the passage of the rays betAAmen them. 
The length of the plate C AAms 12‘0G centims., measuring from the centre of the air 
spaces. The distance betAA-een the plates AAms 4TG centims. The rays, before entering 
