Observations on Colonel Taylor’s Letter. 65 
crop (no matter of what) the richer the land is left; 
the grain thrives best through tap rooted grass.” I give 
this as their idea—for Mr. Taylor’s experiment, “ Sep- 
tember 17th to 5th October” [and many might be ad- 
ded] disprove one, at least of their principles. The 
wheat was worst among the plaistered bird-foot clover 
[‘‘why.”’*] They say, that ‘ vegetable cover excludes 
heat, and admits light ; and these are distinct elemen- 
tary substances, though generally found together. 
Light, with hydrogen and carbon (the materials of o7/) 
is the vivyfying power of vegetation; but radiant heat 
is hostile. Enough Aght is admitted under the cover, 
and radiant heat is excluded.” Although it cannot be 
denied that Light is essential to the life and growth of 
plants, which can be raised to maturity in caves, by 
lamp light, it does not fertilize the soil. They do not 
make allowance, either, for the exhaustion of a heavy 
crop. What will they say to Mr. Taylor’s dead cover of 
cedar &c; or to a door, or board, lying on the surface ; 
and fertilizing; by preventing evaporation, and the ex- 
traction by the sun [or a crop] of what the air impreg- 
nates? And yet admitting, not ight but, the acidified 
gases, carbon &c. which create and support vegetable 
* To the “why” of Mr. T. I have no decisive or techni- 
¢al answer. Probably, the under crop of grass prevents from 
perspiration, and stagnates in the lower joints of the wheat- 
stalks, more juices than can circulate through the plant, 
There are greater demands for food, by both plants, than the 
earth can supply. The strongest and most forward plant ob- 
tains the mastery. Thick and strong wheat, often choaks clo- 
ver. . R. P., 
VOL. If. I 
