20 * OUTLINE OP THE COURSE OF LECTURES. 



and ralue of its (Hscoveries, and the agriculturist may well be pardoned 

 for not keeping j)ace with the advances of a department cf science, 

 which even the professed and devoted chemist can scarcely overtake. 



I might advert also to the mechanical operations of ploughing, wheth- 

 er common or subsoil, of fallowing, draining, weeding, and many 

 others, as being only so many methods by which chemical action is in- 

 duced or facilitated ; — to the growth of plants, and even to such ob- 

 served differences as that of the relative quantity of leaves and tubers in 

 the potatoe, and of grain and straw in our corn-fields, as interesting 

 cases on which scientific chemistry throws a flood of light. I might 

 shew how the feeding of your cattle and the raising and management 

 of dairy produce are not beyond the province of chemistry, but that the 

 only approach to scientific principle yet made, even in these branches 

 of husbandry, is derived from the results of chemical research. 



But I do not dwell on any of these points: they will all hereafter 

 come under our review in their appropriate order, and will afford me an 

 opportunity of laying before you many important facts, as well as, I 

 hope, valuable practical deductions and observations. 



While, however, I feel justified in saying thus much of the light 

 which existing chemical knowledge throws on the natural processes of 

 vegetation, and on the artificial methods of practical agriculture, I 

 would not lead you to suppose that our knowledge is by any means 

 complete, that there are not many points over which much darkness 

 still rests — that some of the theoretical views now entertained are not 

 crude, adopted too hastily, and generalized too rapidly. But a similar 

 confession may be made in reference to all the modern sciences of ob- 

 servation without diminishing their importance or detracting from the 

 value of the facts they embody. Human science is progressive in all 

 its branches, and to refuse to follow the indications of existing know- 

 ledge because it is to some extent uncertain, would be as foolish as to 

 refuse to avail ourselves of the morning's light, because it is not equal 

 to that of the midday sun. 



1 advance, therefore, to the special object of these lectures, and I shall 

 first present you with a rapid outhne of the method which I intend to 

 follow. It is indispensable that this method should be simple, and that 

 every consecutive portion should be so fitted to clear the way for, and 

 thp3w light upon, what is to follow, that we may be able to advance 

 fron? the first rudiments to the most difficult and abstruse parts of our 

 subject, without any chance of the illustrations being even difficult to 

 comprehend. This end I do not hope perfectly to attain, but it will be 

 my constant aim, and, with due attention on your part, I do not fear 

 that we shall fail in arriving at a perfect understanding of the various 

 points to which I shall have occasion to direct your attention. 



I propose, therefore, to bring before you — 



I. The constitution of vegetable substances with the properties of the 

 elementary and compound bodies which either enter into the substances 

 of plants or contribute to their growth and nourishment. 



II. The general structure and functions of the several parts of nlflnffl 



