to the Roots of Plants. 



243 



hot-air chamber ; e, the steps and platform ; f, the line of water ; 

 and g the ground. This was for the purpose of ascertaining 



Fig. 17. Niveri's Pine-Pit. 



what the effect would be from the application of a powerful heat 

 from below on a bed of soil immediately above, and, conse- 

 quently, on the crowns and suckers placed free under such cir- 

 cumstances. It may be well here to premise that the whole 

 extent of the bottom of the pipe-chamber beneath said bed 

 or border is capable of being made an evaporating surface at 

 pleasure, by the introduction of water ; an arrangement, in my 

 opinion, that must in all cases accompany the introduction of 

 artificial heat to the roots of plants ; but which, it will at once 

 appear, is as simple as the method of introducing the heat itself. 

 The manner of constructing the artificial bed of soil thus to be 

 heated was exactly a miniature of what I have described in the 

 case of the formation of my vine borders, namely, a substratum 

 of broken brick-bats, about 6 or 8 inches in thickness ; then 

 a thin sod, turned grass side down, neatly laid all over; 

 whilst over this were laid about 3 in. of half-rotten leaves, and 

 then a light, rich, sandy compost of suitable soil, about 6 in. 

 in depth; the whole being firmly pressed down previously to 

 the insertion of the plants. After these simple preliminaries 

 the crowns and suckers were inserted firmly in the bed of soil, 

 with a small portion of sea-sand around the stem of each. They 

 were placed in lines along the bed, the plants alternating with 

 each other, and at such distances as to allow of free and full 

 growth throughout the season. Thus, at once, without any delay 

 in waiting for the rising or falling of the heat, the whole was 

 finished off complete. The only care afterwards, throughout the 



r 2 



