PEEFACE TO SECOND EDITION. 



PROBABLY many of the persons who will see this Preface, 

 are aware that I contributed to the " Quarterly Keview " an 

 article on Agricultural Drainage, which appeared in its 171st 

 Number, and which, in the year 1850, was reprinted by 

 Mr. Murray in a separate form. Mr. Murray has now re- 

 quested that I will revise this reprint for a second edition. 

 It would be troublesome to divest the thing of its reviewing 

 form ; but as it has become a treatise, I think that I may 

 drop with advantage the critical spirit. I have, therefore, 

 struck out several passages having reference to controversial 

 writings, which it is no longer necessary to keep before the 

 public; I have woven into the treatise a few matters which 

 further experience and observation have brought to my 

 notice ; but the main principles and arguments remain as 

 they were. I have increased confidence in them. Since 

 the article was first written, I have continued to employ in 

 draining from 15 to 20 men both winter and summer. A 

 drain made in summer is, in the article of excavation, ge- 

 nerally somewhat more costly than the same work executed 

 in winter ; but it is less liable to injury from slips, or to 

 interruption from bad weather. The carting of materials is 

 also less troublesome in summer, and the work is generally 

 executed in a cleaner and more perfect manner. I am 

 partial to summer draining when it can be done without 

 unreasonable interference with crops. Several of my neigh- 

 bours carry on drainage perseveringly on the system which 

 I have endeavoured to explain ; and I believe that, without 



