While the draining thus proceeds on the best and most economical principles, the ploughing is supposed to be still in progress. Indeed the arrangements for the two operations, the selection and purchase of the implements for both, may go on simultaneously. The plough, indeed, is sometimes used as a draining implement for making a deep furrow, in which, with more or less emendation from the spade, the tiles or other draining materials may subsequently be laid. But in this case, the draught is excessive, and many horses must often be yoked into the same plough, in order to drag it through the ground. Here, therefore, the young farmer must learn a new art--the art of harnessing and yoking his horses, in such a way as to obtain the greatest possible effect, at the least expense, or with the smallest waste of animal strength. This is a very important subject for consideration, and it is one which the author who is best acquainted with the practice, and with the state of knowledge regarding it, over a great part of our island, will feel himself most imperatively called upon to treat of in detail. This is done, accordingly, in the chapter upon the "Yoking and Harnessing of the Plough," in which, by the able assistance of Mr. Slight, the principles upon which these processes should be conducted, as well as the simplest, strongest, and most economical methods, in actual practice among the most skilful farmers, are illustrated and explained. To this follows a chapter upon "Ploughing stubble and lea ground," in which, with the aid of his two coadjutors, the practical and scientific questions involved in the general process of ploughing such land, are discussed with equal skill and judgment. We have been particularly pleased with the remarks of Mr. Slight upon ploughing-matches, (Vol. i. p. 651,) in reference especially to the general disregard among judges, of the nature of the _underground_ work, on which so much of the good effects of ploughing in reality depends. They will, we doubt not, have their due weight, at future ploughing-matches, among those--and we hope they will be many--into whose hands the work before us may come.