34 



GENESEE FARMER. 



Mar. 1845 



THE STUDY OF AGRICULTURE. 



Extracts from an unpublished IVork. 



MINERALS AND ROCKS. 



Every part of the globe which is not animal nor 

 vegetable, including air and water, is regarded as 

 mineral. 



The term " rock,'' in popular language, embraces 

 only the solid part of the earth : but in geological 

 language it includes all loose materials, such as 

 soil, clay, gravel, and loam. 



Taken a's a whole, the earth is about five times 

 heavier than water, and two and a half times heavier 

 than common rocks. The density of the globe in- 

 creases from the surface to the centre. At the 

 depth of 34 miles, air would become as heavy as 

 water, and at the depth of 362 miles water would 

 become as heavy as quicksilver. At the centre of 

 the earth, stcel'would be compressed to one-fourth, 

 and a stone into one-eighth of its bulk at the 

 surface. 



The rocks which compose the globe are divided 

 into two great classes — stratified and unstrati- 

 riEi) rocks. 



The latter are supposed to have been a melted 

 mass, which, on cooling, formed a very hard, crys- 

 talline rock, like granite. Such rocks are of great and 

 unknown thickness, and without stratification. 



All rocks formed in water are stratified, or deposit- 

 ed in regular masses, usually on nearly parallel 

 planes, varying in thickness from that of paper to 

 many yards. Although, as a general rule, the lines 

 of stratification are parallel, or nearly so, they often 

 converge in one direction, and of course diverge in 

 the opposite direction, giving the strata, or layers of 

 rock, a wedge-like form. 



It is believed by geologists, that the globe was 

 once in a liquid, if not gaseous state. Its shape is 

 precisely what a fluid would assume — an " oblate 

 spheroid" — if it revolved on its axis with the known 

 velocity of the earth. It is 36 miles farther through 

 at the equator than at the poles. The crystalline. 

 form of all the rocks that lie below those that have 

 been deposited and stratified in water, furnishes 

 Btrong presumptive evidence that these ancient 

 rocks" called " primitive" and " granite," were crys- 

 tallized by the cooling of a liquid mass, just as wa- 

 ter is crystallized when frozen into solid ice by re- 

 ducing its temperature below 32 degrees. 



If we admit that the now solid crust of the earth 

 was once a melted mass, it is obvious that water 

 must have existed in a state of vapor, or in the form 

 of simple gases — that is, in oxygen and hydrogen 

 gases. These are very light, and invisible, like com- 

 mon air. Many other substances beside water — 

 particularly carbon, the substance that burns in 

 wood, coal, oil and tallow, snlphur, phosphorus, and 

 other combustibles — would have existed only in the 

 vastly expanded and intensely heated atmosphere. 



After the globe had cooled sufficiently to permit 

 vapor to condense into water, and form an ocean 

 around the earth, it would seem that all the carhon 

 that now lies in coal-beds over much of the surface 

 of the planet, and in the carbonic acid which is com- 

 bined with immense and unknown quantities of lime 

 rock, often some thousands of feet in thickness, and 

 of vast extent — must all have been in a gaseous state. 

 It is obvious, that an atmosphere thus loaded with 

 carbon, sulphur, and other poisonous gases, could 

 not support any of the higher order of animals, or 

 more perfect plants. The way in which this bad at- 



mosphere was purified, and a barren granite rock 

 rendered the fit habitation for the highest class of 

 animals, with man at their head, is worthy of con- 

 sideration. * * « * 



There can be little doubt that internal heat, deep 

 in the bowels of the earth, elevates more or less fre- 

 quently, and to a greater or less extent, large sec- 

 tions or tracts of the earth's smface. By this means 

 islands, mountains, and whole continents may, in the 

 course of ages, be raised by slow upheavings from 

 the bottom of the deep sea. Mountains several 

 miles above the level of the ocean are very common; 

 and some of them are composed, in part, of rocks 

 many thousand feet in thickness, having the remains 

 of marine animals imbedded in them, showing that 

 these rocks were deposited in water, and entombed 

 living animals in their once-soft mass. Marine 

 shells are often found miles above the present level 

 of the sea. Either the ocean must have fallen some 

 eight or ten thousand feet over its whole surface, or 

 these fossiliferous rocks must have been elevated 

 from the bed of an ocean where they were formed. 

 The latter supposition is doubtless the true one. 



De la Beche estimates the average height of dry 

 land above the ocean at two miles. The average 

 depth of the ocean is thought to be not far from two 

 and a half miles. As nearly three-fourths of the 

 earth's surface is covered with water, it follows, 

 from the above facts, that aM the land above the level 

 of the ocean might be washed by rains antl rivers in- 

 to the sea, and not half, or more than half, fill it up. 



The repeated upheaval, and sinlcing down of ditFer- 

 ent portions of the earth's crust, have subjected ev- 

 ery part of our planet to elevation into dry land — 

 islands and continents — and depression into the bed 

 of an ocean, 



ORGANIC structure AND FUNCTIONS OF CUIiTI- 

 VATED PLANTS. 



To the practical farmer and gardener, plants may 

 be regarded as machines, which transform the raw 

 materials of grain, roots, hay, flax, hemp, tobacco, 

 and cotton, into those valuable products. Hitherto 

 we have studied the geological and chemical charac- 

 ter of plants and animals as they exist in rocks, in 

 soil, in u-aier, and in the atmosphere. 



We have now to study them when subject to the 

 control of new laws, which break up previous chem- 

 ical combinations, and form peculiar compounds, un- 

 like any inorganic product, and without which all 

 animal life would speedily become extinct. Regard- 

 ing a cultivated plant as a living machine, which, if 

 properly tended, will change stone and dirt into bread 

 and honey, aside from the interest of the subject aa 

 a matter of science, we should investigate the struc- 

 ture of this curious machine, and the /miction or of- 

 fice performed by every part, that it may operate at 

 all times to the very best advantage. 



In treating of the organic structure of plants, 

 with reference not to their botanical character, but 

 to increase their quantity, and improve their (]uality 

 by judicious culture, they maybe divided into Roots, 

 Stems, and Leaves. 



ROOTS THETR STRUCTURE AND FUNCTIONS. 



When a seed is made to sprout, the part of the 

 new living being which is firs^ developed, and buista 

 the membrane that incloses the seed, is called the 

 radicle, or root. This shoots downward, as if in 

 search of nourishment from its parent earth. Con- 

 nected with the radicle, a portion of the infant plant 

 shoots upward, as if in search of the light and heat 



