VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 239 



of ammonia, in the form of sulphate, carbonate, nitrate, and 

 muriate of ammonia. Now, the same quantity will be fur- 

 nished by one quarter of a ton of good Peruvian guano, at prob- 

 ably one half the cost, while its application, in a liquid state, is, 

 more immediately beneficial to the vines. The same salts are 

 supplied from urine, which ought to be collected in tanks for 

 that purpose. By the addition of these elements, an impover- 

 ished border, incapable of yielding one fifth of a crop, has been 

 enriched and made to produce good crops of fruit. As I have 

 said, however, I would have a border made, say, 12 or 16 feet 

 wide, of good open material, not over-rich in nitrogeneous mat- 

 ter, but abundantly mixed with lumps of charcoal, and plenty of 

 bones ; a quantity of common lime-stone (carbonate of lime) 

 might be laid on the bottom, and mixed through the mass. 

 With a border so formed, about 2 feet deep, and 14 feet wide, 

 by the regular application of nutritious elements in a liquid 

 form, and proper management in other respects, the most abun- 

 dant crops may be produced, for at least a quarter of a century. 

 We are well aware of the arguments that are brought to bear 

 against shallow vine-borders in this country, from their greater 

 liability to become dried up by the parching droughts of sum- 

 mer. But here this argument can have no application, as the 

 season of forcing is at that period when the ground is saturated 

 with wet, and little or no abstraction of it by the atmosphere. 

 And as the temperature of any piece of ground is nearly in 

 exact proportion to the amount of water it contains, so it follows 

 that a vine-border saturated with water must necessarily be 

 colder, and consequently more injurious to forcing plants, than 

 a dry one, even without heat! It is true, a border may be 

 drained, and all superfluous and stagnant moisture carried off, 

 but even the driest and most silicious soils have a certain 

 capacity of suspending moisture, in their pores, and as this 

 capacity is greater in soils containing much organic matter than 

 in those of a more sandy nature, it follows theoretically, and 

 we find it so in practice, that rich borders are colder and 

 wetter than the common garden soil. I believe this is a fact 

 which no one will dispute. But however warm vine-borders 

 may be by their natural position, or rendered so by artificial 

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