AND HORTICULTURE. 65 
If we number the kinds of plants with which experi- 
ments are to be made, 
rt 2 $3 4 & © 
it is safest to sow them as indicated in the figure. The 
plants No. 1 are sown where we have E, and C,, &c. In such 
an arrangement we shall get three experimental fields and 
threé control fields for every sort. If there is any inequality 
in the soil it will, for the most part, be eliminated by the 
results from the three fields.* 
The seed must, of course, be chosen with much care, and 
must be as equal as possible for both kinds of fields. 
Fic. 9. 
If a general application of electricity is to be given, the 
posts are to be fixed as shown in Fig. 9. In this figure the 
round dots signify posts provided with insulators, as 
described below. Along these insulators the wire is carried. 
III. 
Fixing the Wire Net and Insulators—Along each range 
of the experimental squares posts, 25 m. in length and 
about 6 cm. in diameter, are rammed in the ground very 
firmly to a depth of } m. and at a distance apart of 14°3 m. 
* See the remarks made on pages 33 and 34, 
F 
