Hints on Vegetation. 18 



On this subject, it has been justly observed by the intelligent Dr 

 Coventry, that such investigations would not only become a source of 

 curious and interesting amusement to those engaged in agriculture, 

 but might likewise prove of real advantage, by furnishing them with 

 many useful hints, for the profitable improvement of their art. Many 

 errors in the cultivation of land have arisen, and been persisted in 

 with much ultimate loss, from ignorance, or mistaken notions, about 

 vegetation, and the circumstances connected with it. 



He adds, that the quantity of accurate information on the subject 

 of vegetation, of which we are yet possessed, when separated from un- 

 certain conjecture, it must be admitted, is extremely small. Still, how- 

 ever, the little which has been already discovered, has proved of signal 

 advantage in gardening ; and there is no reason, why it should not like- 

 wise contribute, in as great a degree, to the improvement of agricul- 

 ture, which is a more extensive, as well as a more economical mode 

 of cultivating the soil. 



To complete however, so important, and so extensive an investiga- 

 tion, would require the united efforts of a number of scientific and 

 practical men, with a sufficient quantity of land at their command, 

 to bring various important particulars to the test of experiment ; and 

 to render such experiments truly useful, this ought to be done on a 

 great scale, and exposed to atmospheric influence. The philosophic 

 experimenter may work successfully in his laboratory, with the object 

 always in his view. But the secret processes of vegetation are car- 

 ried on in the dark, exposed to the various and uncertain influences 

 of the atmosphere, and require in general, a considerable period of 

 time for their completion. Hence the difficulty of determining, on what 

 peculiar circumstances success or failure d epends ; and hence a diver- 

 sified experience, carried on for a number of years, and in the open air, 

 can alone afford a sure foundation, for such specific conclusions as can 

 be confidently relied on *. 



Additional Hints on Vegetation, and the Culture of Potatoes. 



Convinced of the importance of light to the production of crops, 

 Mr Knight has tried a peculiar method of raising potatoes, by which 

 he procured the enormous crop of 670 bushels, (80 pounds each), 

 from an English acre, equivalent to 804 bushels per Scotch acre. His 

 system is, to plant large tubers, weighing generally, (if the variety of 

 the potatoe be large), at least half a pound each. These sets he does 

 not put at a greater distance, (from centre to centre), than six inches 

 in the row ; but he leaves wide intervals between the rows, not less, 

 when the soil is good, and the varieties of luxuriant growth, than 4 

 feet. Special care is taken to make the rows lie from south to north. 

 Under this mode of treatment, very large plants, presenting a wide ex- 

 tent of surface to the light, very early in the summer, are generated. 

 The wide intervals between the rows, admit the free operation of light 

 upon the plant, afford space for clearing them of weeds, and allow, with- 

 out impediment, the beneficial influence of the atmosphere. The crops 



Kirwan on Manures, p. 4. 



