ADVERTISEMENT ΤΟ THE FOURTH EDITION. DURING ten years, from 1802 to 1812, I had the honour, every Session, of delivering Courses of Lectures before the Board of Agriculture. I endeavoured, at all times, to follow in them the progress of discovery; they therefore varied every year and since they were first published in 1813, some considerable improvements have been made in chemical science, which have rendered many alterations and additions necessary. I am indebted for much useful information to many gentlemen who have endeavoured to improve Agriculture, and to apply scientific principles to this most important of the Arts; of which acknowledgments will be found in the body of the Work. I hope there are no omissions on this head; but should they exist, I trust they will be attributed to defect of recollection, and not to any want of candour or of gratitude. Where I have derived any specific statements from books, I have always quoted them; but I have not always made references to such doctrines as are become current, the authors of which are well known; and which may be almost considered as the property of all enlightened minds. In revising this work for the fourth edition, I have been forcibly struck with its imperfections, and I regret that I have been able to do so little to render it more worthy of the approbation of those readers for whom it was designed. My object has been principally to dwell upon practical principles and practical applications of science; and it is in the farm and not in the laboratory that these can be put to the test of experiment, and my duties and pursuits have rendered it impossible for me to do more than point out the path of inquiry to indicate the road to improvement. The manner in which the work has been received, both in this country and the Continent, induces me to hope that its object, however humble, has been to a certain extent attained, and that it has not been without its utility. I have retained an Appendix containing an account of the experiments on Grasses instituted by the Duke of Bedford at Woburn, because many of these experiments are alluded to in the body of the work. I am happy, however, to be able to refer my readers to a much fuller and more detailed account of this subject of investigation, in a treatise published by Mr. George Sinclair, entitled Hort. Gram. Woburnensis, and which, from the nature of the details, and the singular modesty and clearness with which they are given, is well worthy the perusal of all persons interested in agricultural pursuits. Park Street, January 1. 1827. H. DAVY. CONTENTS. LECTURE I. Page Of the general Powers of Matter which influence Vege- tation; of Gravitation, of Cohesion, of Chemical Attrac- tion, of Heat, of Light, of Electricity; Ponderable Sub- On the Organisation of Plants. Of the Roots, Trunk, and Branches; of their Structure. Of the Epidermis. Of the cortical and alburnous Parts of Leaves, Flowers, and Seeds. Of the chemical Constitution of the Organs of Plants, and the Substances found in them. Of mucilagin- ous, saccharine, extractive, resinous, and oily Substances, and other vegetable Compounds; their Arrangements in Of Manures of vegetable and animal Origin: of the Manner in which they become the Nourishment of the Plant. Of Fermentation and Putrefaction. Of the different Species of Manures of vegetable Origin: of the different Species of animal Origin. Of mixed Manures. General Prin- On Manures of mineral Origin, or fossil Manures: their Preparation, and the Manner in which they act. Of Lime in its different States. Operation of Lime as a Manure and a Cement. Different Combinations of Lime. Of Gypsum: Ideas respecting its Use. Of other On the Improvement of Lands by Burning. Chemical Principles of this Operation. On Irrigation and its Effects. On Fallowing its Disadvantages and Uses. On the convertible Husbandry founded on regular Ro- tations of different Crops. On Pasture. Views con- |