66 ELECTRICITY IN AGRICULTURE 
Every corner-post must have on the inner side (the side 
of the experimental field) a short stout support to resist 
the strain of the iron wire. The insulators (Fig. 10) have 
now to be firmly fixed to the posts, putting the ring 
around the post and drawing the screw. 
When the insulators are well fixed, galvanised iron wire 
(of 1-5 mm. diameter) is carried with a medium tension 
along the posts, over the porcelain bell of the insulator. 
The wire is put round the bell and fixed with a separate 
‘short wire. 
Fic. 10.—4, ring ; e, ebonite tube ; z, iron bar; 9, porcelain bell; Z, post. 
When these conducting wires have been fixed all round 
the experimental field, cross-wires of about o°6 mm. diameter 
are laid on them from one side to the other at a distance 
of about 1°25 m., and in this way eight cross-wires cover 
10m. This finer wire must be furnished, at I m. apart, 
with small points 2 cm. in length, nearly similar in appear- 
ance to the well-known barbed wire. 
The wire net, being now fully insulated from the posts, 
is, as stated above, connected by means of a well insulated 
conducting wire to the positive pole of the electric machine, 
the negative pole being conducted to earth by means of a 
