CHERRIES AND LETTUCES, HOW FORCED. 149 



I entertain little doubt that the time is at hand when it will he 

 considered quite as necessary to furnish heat for the soil as- for 

 the air; not, however, heat without moisture, for that would 

 evidently produce much greater evils than it was intended to 

 cure, as has indeed been found by inconsiderate experimenters. 

 Mr. Writgen is probably right in believing that it is the 

 temperature and moisture of a soil quite as much as its 

 mineralogical quality, that determine its influence upon vegeta- 

 tion. (See Erster Jahresbericht, dc, am Mittel und Nieder- 

 Bhein,. p. 64.) It must not, however, be supposed that the 

 nature, whether chemical or physical, of soil is unimportant. A 

 crop of wheat cannot be had on peat, nor will salt plants thrive 

 when the soil contains no marine salt. 



Mr. Fintelinann, the king of Prussia's gardener at Potsdam, 

 is celebrated for his success in the difficult art of forcing 

 Cherries, and he has given an account of his practice {Gard. 

 Mag., vol. iii., p. 64), in which it appears that the most pecuKar 

 feature is the strict attention he pays to the temperature of 

 the roots. He first soaks the roots in water heated by the 

 mixture of equal parts of boiling and cold water ; he afterwards 

 sprinkles the trees with luke-warm water, and he continues to 

 employ it of the same temperature as long as watering is 

 required. Thus his roots are constantly maintained at the 

 requisite temperature by the trickling of the warm water into 

 the soil. 



It seems, indeed, clear, that the success of the Dutch in 

 obtaining an abundance of fresh vegeta]j)les, such as Lettuces, 

 during the whole winter, is in part owing to their being able to 

 maintain a gentle bottom heat. No doubt this is connected 

 with the abundant light which their forcing structures admit, 

 and with other causes of considerable importance, such as an 

 abundant, constant, and skilful introduction of fresh air; but 

 none of those causes can be supposed likely, in the absence 

 of the bottom heat, to produce such a result as the Dutch 

 gardeners obtain. 



If it is necessary that the temperature of the soil in which 

 plants grow should be carefully regulated, and adjusted to their 

 natural habits, it is no less requisite that the water in which 



