10 INTRODUCTION. 



were built, on account of a deficiency of knowledge on the part 

 of those who superintended their erection. 



It is a common error for gardeners, and others, who erect 

 glazed structures, to suppose that the kind of house perfectly 

 suitable in one place will be equally so in another ; or that the 

 same arrangement answerable for one purpose will answer 

 equally well for all purposes to which a glazed structure may 

 be applied. Some of the consequences of these errors will be 

 more particularly specified in a subsequent part of this work ; as 

 also the external forms and internal arrangements which we 

 have found most suitable to the different purposes. The influ- 

 ence which a servile adherence to old methods has upon the 

 progress of horticulture, is chiefly manifest to those who are 

 most liable to be censured for innovations. Yet it is doubtful 

 whether the odium incurred is not more than compensated by 

 the pleasure which arises from the rewards of perseverance, by 

 which we are enabled to abandon bad systems, as we gain more 

 confidence in those that are better. 



It is said that practice is the best of all teachers ; that as our 

 practice is lengthened, our experience is increased. However 

 this axiom may hold good in the common affairs of life, it is 

 frequently reversed among practical men, and years pass away 

 without any enlargement of knowledge, or rectification of 

 judgment. There are, indeed, many who never endeavor to 

 improve, notwithstanding the opportunities which may be 

 afforded them. The opinions they have received, and the 

 practice they have learned, are seldom recalled for examination, 

 and, having once supposed them to be right, they can never 

 discover them to be erroneous. From this preconceived acqui- 

 escence, few are entirely free ; from a dislike to apparently super- 

 fluous labor, and from a fear of uncertain results, many stand 

 still when they might go forward. 



Some may say, that if a practical man performs the operations 

 which others have taught him, and succeeds as well as others 

 have done, he does all that can be expected from him. But this 

 is doing nothing for improvement, and very little for himself. 

 It is every man's duty to endeavor to excel, both on account 

 of his profession and of himself, as well as those who employ 



