AND HORTICULTURE, 37 
by small pieces of ebonite. In Section IV., which ought 
to serve as control, the pots with their plates stood on the 
same kind of insulating layer, but with no zinc strips 
beneath nor wire net above. 
After having found a new way to determine the situation 
of the poles at the influence machine, we could easily con- 
trol this each time the machine was set in motion. When 
the machine is allowed to work without Leyden jars, and 
its poles are at a distance of 1°5’cm, a stream of light 
can be observed between the poles. This fine light is 
violet at the negative pole, ending with a bright point on 
.the surface of the sphere ; but it is white and very bright at 
the positive pole. The change of colour in the light-current 
does not take place in the middle, but is nearer to the 
positive pole. 
The influence machine used ‘on this occasion was of the 
new type, with small cylinders (15 cm. diameter and 20 cm. 
in length), and enclosed in a glass box, in which was placed 
a little plate with sulphuric acid for the drying of the air 
The machine was set in motion by an electrodynamic motor, 
into which was led a current of from five to six Daniel 
elements. The negative pole of the machine was placed 
in connection : 
‘In Section I., with the zinc strips underneath the pots, 
the wire net of the same section being led off to 
earth ; 
In Section II., with the wire net above the pots, the 
zinc strips of this section being led off to earth ; 
In Section III, with.a commutator of ebonite (lying 
on a plate of glass) through which a leading con- 
nection could be produced, one day with the zinc 
strips and the other day with the wire net, in the 
same section. At the same time the commutator 
effected a connection so that one day the wire net and 
the other the zinc strips were united with the earth ; 
In Section IV., no current. 
