1 90 Bibliography. 



urgent, and in that country acquires a vastly superior importance. When a tract 

 of land is thinly peopled, like the newly settled districts of North America, New 

 Holland, or New Zealand, a very defective system of culture will produce food 

 enough not only for the wants of the inhabitants, but for the partial supply of 

 other countries also. But when the population becomes more dense, the same 

 imperfect or sluggish system will no longer suffice. The land must be better till- 

 ed, its special qualities and defects must be studied, and means must gradually be 

 adopted for extracting the maximum produce from every portion susceptible of 

 cultivation." 



The British Islands are in the latter condition. Supposing importa- 

 tion from abroad not to have increased to any important extent, it ap- 

 pears that the soil of Great Britain has, by improved manage naent, been 

 made to yield twice the quantity of food it afforded half a century ago ; 

 and the important question arises, whether the domestic supply may be 

 expected still to increase in the same ratio with the population, or whe- 

 ther the deinands of the latter will not soon overtake the productive 

 powers of the land. In view of what has already been accomplished, 

 and of the abundant room for further improvement, our author hints, 

 that a portion of the strength expended by the agricultural interest in 

 attempting to secure or maintain important political advantages in the 

 state, might with propriety be devoted to the encouragement of experi- 

 mental agriculture. The suggestion is as important as it is opportune. 

 After presenting a plain account of the difference between simple and 

 compound bodies, organic and inorganic matter, and briefly exhibiting 

 the properties of the four organic elements of plants, viz. carbon, oxy- 

 gen, hydrogen and nitrogen. Prof. Johnston concludes his first lecture 

 with the following remarks : 



" Such are the several elementary bodies of which the organic or destructible 

 part of vegetable substances is formed. With one exception they are known to 

 us only in the form of gases ; and yet out of these gases much of the solid parts 

 of animals and of plants are made up. When alone, at the ordinary temperature 

 of the atmosphere they form invisible kinds of air ; when united, they constitute 

 those various forms of vegetable matter which it is the aim and end of the art of 

 culture to raise with rapidity, with certainty, and in abundance. How difficult to 

 understand the intricate processes by which nature works up these raw materials 

 into her many beautiful productions — yet how interesting it must be to know her 

 ways, how useful even partially to find them out ! Permit me, in conclusion, to 

 submit to you one reflection. We have seen that oxygen, hydrogen, and nitrogen, 

 are all gaseous substances, which when pure are destitute of color, taste, and 

 smell. They cannot be distinguished by the aid of our senses. Man in a state of 

 nature — uneducated man — cannot discern that they are different. Yet so simple 

 an instrument as a lighted taper at once shows them to be totally unlike each other. 

 This simple instrument, therefore, serves us instead of a new sense, and makes us 

 acquainted with properties the existence of which, without such aid, we should not 

 even have suspected. Has the Deity then been unkind to man, or stinted in his be- 

 nevolence, in withholding the gift of such a sense .' On the contrary, he has given 

 us an understanding, which, when cultivated, is better than twenty new senses. 



